METHODS AND COMPOSITIONS FOR DELIVERY OF A THERAPEUTIC AGENT

Abstract

Compositions of hyaluronic acid (HA) conjugated with antibiotics are disclosed for a rapid release antibiotic delivery system into a closed space to achieve rapid therapeutic range within 24 hours and effective elimination of the antibiotic within 80-120 hours. In particular, this invention is directed to compositions, method of preparation, and method of treatment to prevent invention using porous and non-porous embodiments of hyaluronic acid polymer conjugated with antibiotics or other therapeutic agents for rapid therapeutic delivery and controlled reduction of therapeutic dosages of antibiotics to prevent invention and reduce antibiotic resistance. Low concentration of crosslinkers conjugated with HA as well as using porogens and functional group modifiers allow other therapeutic to be conjugated to HA such as sugars and steroids. Suspension of HA conjugates in chitosan enable additional treatment means. Anti-cancer therapeutic agents may also be conjugated for controlled release using this system.

Claims

1. A method of preparing a porous biologically active rapid release therapeutic agent polymer, the method comprising: (a) providing an alkaline solution of hyaluronic acid (HA), or a salt thereof, having HA repeating units; (b) providing a simple carbohydrate solution prepared in approximately a same mole ratio of the HA repeating unit of step (a); (c) mixing at least a portion of the solution of step (a) and the solution of step (b) together into solution, (d) mixing the solution of step (c) with a solution of AOT; (e) mixing the solution of step (d) with a crosslinking agent; (f) agitating for a sufficient time and at a sufficient temperature the solution of step (e) to produce HA particles thereby creating crosslinked HA repeating units and the simple carbohydrate; (g) precipitating the solution of step (f) HA particles; (h) mixing a therapeutic agent solution with the HA particles of step (g), wherein the therapeutic agent solution comprises a therapeutic agent, thereby forming an HA-carbohydrate-therapeutic agent conjugate.

2. The method of claim 1, wherein the alkaline solution is NaOH; wherein the simple carbohydrate is sucrose; wherein the therapeutic agent solution is an antibiotic solution comprising an antibiotic, thereby forming an HA carbohydrate-antibiotic conjugate; and, wherein the crosslinking agent is at least one of glycerol diglycidyl ether (GDE), trimethylolpropane triglycidyl ether (TMPGDE), sodium trimetaphosphate (STMP), and divinyl sulfone (DVS), and is at a concentration of approximately 50 to 200 mole percent relative to HA repeating units.

3. The method of claim 2, wherein the antibiotic is selected from the group consisting of Ciprofloxacin and Vancomycin and wherein the antibiotic is conjugated with 1,1′-carbonyldiimidazole (CDI), in a solution of dimethyl sulfoxide (DMSO).

4. The method of claim 3, wherein mixing the antibiotic solution with the HA particles for a predetermined amount of time at a predetermined temperature.

5. The method of claim 4, wherein the predetermined amount of time is approximately 24 hours and the predetermined temperature is approximately 80° C.

6. The method of claim 1, further comprising the steps of: (a) providing a chitosan solution; (b) suspending the HA-therapeutic agent in the chitosan solution, thereby creating a viscous solution capable forming a viscous layer upon a target tissue surface.

7. The method of claim 6, wherein the chitosan solution is prepared by dissolving chitosan in a solution of acetic acid and water.

8. The method of claim 6, further comprising steps of: (a) providing a steroid solution having at least one steroid; (b) mixing the steroid solution with the HA-carbohydrate-therapeutic agent conjugate to conjugate the steroid, thereby forming an HA-carbohydrate-therapeutic agent-steroid conjugate.

9. A method of preparing a biologically active rapid release therapeutic agent particles, the method comprising: (a) providing an alkaline solution of hyaluronic acid (HA), or a salt thereof, having HA repeating units; (b) providing a solution of crosslinking agent wherein the crosslinking agent is at a ratio of between 1 percent mole and 20 percent mole relative to the HA repeating unit; (c) mixing the solutions of steps (a) and (b), thereby forming crosslinked HA particles; (d) precipitating the crosslinked particles formed in step (c) using a precipitating agent; and, (e) mixing a therapeutic agent solution with the HA particles, wherein the therapeutic agent solution comprises a therapeutic agent, thereby forming an HA-therapeutic agent conjugate.

10. The method of claim 9, wherein the therapeutic agent solution is an antibiotic solution, thereby forming an HA-antibiotic conjugate.

11. The method of claim 10 wherein the crosslinking agent is divinyl sulfone (DVS).

12. The method of claim 10, wherein the crosslinking agent is of a ratio of between 1 percent mole and 10 percent mole relative to the HA repeating unit.

13. The method of claim 10, wherein the crosslinking agent is at a ratio of between 1 percent mole and 5 percent mole relative to the HA repeating unit.

14. The method of claim 10, wherein the crosslinking agent is at a ratio of between 1 percent mole and 2.5 percent mole relative to the HA repeating unit.

15. The method of claim 10, further comprising the steps of: (a) providing a solution of at least one of trimethylolpropane triglycidyl ether (TMPGDE), 3-chloro-2-hydroxy-1-propanesulfonic acid, 4-bromo butyronitrile, bromoacetic acid, tris(2-aminoethyl)amine, cysteamine, and bromo- or chloro-alkanes, wherein the bromo-alkanes characterized has having a formula of Br(CH.sub.2).sub.nCH.sub.3, wherein n is between 1 and 17, and the chloro-alkane is chloro 3-chloropropylamine; and, (b) suspending the porous-HA particles formed in any of claims 9-14 in the solution, thereby introducing at least one of —OH, —SO.sub.3H, —CN, —COOH, —NH.sub.2, —SH, and R functional groups for conjugate attachment.

16. The method of any of claim 15 further comprising the steps of: (a) providing a steroid solution having at least one steroid; and, (b) mixing the steroid solution with the HA-antibiotic conjugate to conjugate the steroid, thereby forming an HA-antibiotic-steroid conjugate.

17. A method of preparing a biologically active rapid release therapeutic agent polymer, the method comprising: (a) providing an alkaline solution of hyaluronic acid (HA), or a salt thereof, having HA repeating units; (b) providing a solution of crosslinking agent wherein the crosslinking agent is at a ratio of between 50 percent mole and 100 percent mole relative to the HA repeating unit; (c) providing a solution of a porogen agent wherein the porogen agent is at a ratio of between 25 percent weight of the HA and 50 percent weight of the HA-polymer; (d) mixing the solutions of steps (a) and (b) and (c); and, (e) precipitating particles formed in step (d) using a precipitating agent; thereby forming porous-HA particles having an average surface area between approximately 21 m.sup.2/g to 0.014 m.sup.2/g, an average pore volume of between approximately 11 cm.sup.3/g and 1 cm.sup.3/g and an average pore size of approximately 7 nm to 13 nm.

18. The method of claim 17 wherein the crosslinking agent is divinyl sulfone (DVS) and the porogen is selected from a group consisting of polyvinylpyrrolidone (PVP), and polyethylene glycol dimethyl ether (PEG).

19. The method of any of claim 18 further comprising steps of: (a) providing a solution of a therapeutic agent having a therapeutic agent; and, (b) mixing the solution of the therapeutic agent with the porous-HA particles of claims 17-18, thereby conjugating the therapeutic agent with the porous-HA particles.

20. The method of any of claim 19, wherein the therapeutic agent is an antibiotic.

21. The method of claim 20, wherein the antibiotic is selected from the group consisting of Ciprofloxacin and Vancomycin.

22. The method of claim 20 further comprising steps of: (a) providing a solution of at least one of trimethylolpropane triglycidyl ether (TMPGDE), 3-chloro-2-hydroxy-1-propanesulfonic acid, and 3-chloropropylamine; and (b) suspending the porous-HA particles in the solution of at least one of trimethylolpropane triglycidyl ether (TMPGDE), 3-chloro-2-hydroxy-1-propanesulfonic acid, and 3-chloropropylamine, thereby introducing at least one of —OH, —SO.sub.3H and —NH.sub.2 functional groups for conjugate attachment.

23. The method of claim 22 further comprising steps of: (a) providing a steroid solution having at least one steroid; and, (b) mixing the steroid solution with the HA-therapeutic agent conjugate to conjugate the steroid, thereby forming an HA-therapeutic agent-steroid conjugate.

24. The method of any claim 23 further comprising: (a) providing a simple carbohydrate solution having a simple carbohydrate; (b) mixing the simple carbohydrate solution with the porous-HA particles thereby forming a porous HA-carbohydrate-therapeutic agent conjugate.

25. A biologically active rapid release therapeutic agent polymer composition comprising: a hyaluronic acid (HA) polymer formed of HA repeating units; a therapeutic agent covalently bound to the HA polymer; and, a crosslinking agent having a ratio of less than 1:5 relative to the HA polymer units; wherein the HA particles have an average surface area between approximately 22 m.sup.2/g to 0.3 m.sup.2/g, an average pore volume of between approximately 5 cm.sup.3/g and 0.8 cm.sup.3/g and an average pore size of approximately 5 nm to 8 nm; wherein the composition can rapidly release a therapeutic agent to achieve a therapeutic range within approximately 24 hours and the therapeutic agent is substantially released from the HA polymer within approximately 80-120 hours after administration, thereby preventing infection and limiting the occurrence of antibiotic resistance after rapid release of the antibiotic from the HA polymer.

26. The composition of claim 25 wherein the therapeutic agent is an antibiotic.

27. The composition of any of claim 26, wherein the crosslinking agent is divinyl sulfone (DVS)

28. The composition claim 27, wherein the crosslinking agent having a ratio of less than 1:5 is less than 1:10.

29. The composition of claim 27, wherein the crosslinking agent having a ratio of less than 1:5 is less than 1:20.

30. The composition of claim 27, wherein the crosslinking agent having a ratio of less than 1:5 is less than 1:40.

31. The composition of claim 26, wherein the HA-polymer further includes a simple carbohydrate conjugated to the HA-polymer, wherein the HA-polymer is an HA-carbohydrate-antibiotic polymer, whereby the simple carbohydrate attracts bacteria to proximate of the antibiotic.

32. The composition of claim 31 wherein the simple carbohydrate is sucrose.

33. The composition of claim 32, wherein the HA repeating units are modified HA repeating units having at least one of modified functional groups of —OH, —NH.sub.2, —COOH, SH, —SO.sub.3H, —CN, and —R functional groups, thereby increasing conjugation sites on the HA polymer for the therapeutic agents.

34. A biologically active rapid release therapeutic agent polymer composition comprising: a porous hyaluronic acid (HA) polymer particles formed of HA repeating units, the porous HA particles formed though addition of a porogen agent having a weight ratio of between 1:10, 1:4 and 1:2 and 1:0 relative to the HA; a therapeutic agent covalently bound to the HA polymer; and, a crosslinking agent having a mole ratio of between 1:2 and 1:1 relative to the porous HA; wherein the porous HA particles have an average surface area between approximately 21 m.sup.2/g to 0.014 m.sup.2/g, an average pore volume of between approximately 11 cm.sup.3/g and 1 cm.sup.3/g and an average pore size of approximately 7 nm to 13 nm; wherein the composition a rapid release therapeutic agent composition that releases a therapeutic agent to achieve a therapeutic range within approximately 24 hours and the therapeutic agent is substantially released from the HA polymer within approximately 80-120 hours after administration.

35. The composition of claim 34 wherein the therapeutic agent is an antibiotic, thereby preventing infection and limiting the occurrence of antibiotic resistance after rapid release of the antibiotic from the HA polymer.

36. The composition of claim 35, wherein the crosslinking agent is divinyl sulfone (DVS) and the porogen is polyvinylpyrrolidone (PVP), and the antibiotic is selected from the group consisting of Ciprofloxacin and Vancomycin, wherein porous HA particles having an average surface area between approximately 21 m.sup.2/g to 0.014 m.sup.2/g, an average pore volume of between approximately 11 cm.sup.3/g and 1 cm.sup.3/g and an average pore size of approximately 7 nm to 13 nm, whereby surface area, pore volume, and pore size can be varied by varying crosslinker and porogen amounts relative to HA repeating units.

37. The composition of any of claim 36, wherein the composition is suspended in a chitosan solution, thereby forming a viscous suspension capable of adhering to tissue.

38. The composition of claim 37, wherein the composition further comprises a steroid bound to the HA polymer.

39. A method of treating or preventing a condition in an animal, the method comprising administering a composition in an effective amount of the compositions of claim 25 or 34.

40. The method claim 39, wherein the method of treating or preventing a condition is treating or preventing a bacterial infection. wherein the composition achieves a therapeutically effect range within approximately 24 hours after administration and is substantially undetectable within approximately 80-120 hours of administration, thereby preventing infection and limiting the occurrence of antibiotic resistance.

41. The method of claim 40, wherein the animal is a human.

42. The method of claim 40, wherein the composition is administered to at least one of a liver, an eye, joint spaces, a brain, and a meningeal space.

43. The method of claim 40, wherein the composition is administered to an eye, post cataract surgery.

44. The method of claim 43, wherein the composition is administered via a spray nozzle system.

45. The method of claim 39, wherein the condition is cancer and the therapeutic agent is selected from the group consisting of Mitomycin C, 5-Fluorouacil and Cisplatin.

46. The method of any of claim 1, 9 or 17, wherein the therapeutic agent is selected from the group consisting of Mitomycin C, 5-Fluorouacil and Cisplatin.

47. The composition of any of claim 25 or 34, wherein the therapeutic agent is selected from the group consisting of Mitomycin C, 5-Fluorouacil and Cisplatin.

48. The method of claim 40, wherein the therapeutic agent is selected from the group consisting of interferons and insulin.

49. The method of any of claim 1, 9 or 17, wherein the therapeutic agent is selected from the group consisting of interferons and insulin.

50. The composition of any of claim 25 or 34, wherein the therapeutic agent is selected from the group consisting of interferons and insulin.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] FIG. 1a illustrates schematic of a crosslinking reaction of linear HA to produce HA particles using GDE and TMPGDE as crosslinkers;

[0054] FIG. 1b are optical microscope images of GDE and TMP with HA, respectively;

[0055] FIG. 1c are scanning electron microscope images of GDE and TMP with HA, respectively;

[0056] FIG. 2 depicts chemical formula of crosslinkers sodium trimetaphosphate (STMP) and poly(ethylene glycol) diglycidyl ether (PEGGE) that can be used in the preparation of HA particles;

[0057] FIG. 3 depicts photographs of HA particles suspended in a chitosan solution;

[0058] FIG. 4 depicts optical microscope images of HA particles crosslinked with GDE;

[0059] FIG. 5a depicts the chemical structure of HA and antibiotic Ciprofloxacin (CP);

[0060] FIG. 5b is a graphical representation of FT-IR spectra of bare HA particles, Ciprofloxacin conjugated HA particles (CP-HA), and CP-HA particles after CP release in PBS at 37.5° C.

[0061] FIG. 6 is a graphical representation of Ciprofloxacin (CP) release profile from CP-HA particles in phosphate buffer saline at (PBS) at 37.5° C.;

[0062] FIG. 7a is a graphical representations of numbers of bacterial (colony forming unit/mL S. aures) growing in different media such as Nutrient Broth (NB, positive control), HA and HA:sucrose particles in the presence NB at 24 h, 48 h, and 72 h incubation times;

[0063] FIG. 7b is a graphical representations of numbers of bacterial (colony forming unit/mL B. subtilis) growing in different media such as Nutrient Broth (NB, positive control), HA and HA:sucrose particles in the presence NB at 24 h, 48 h, and 72 h incubation times;

[0064] FIG. 8 depicts optical microscope images of HA microparticles crosslinked with DVS at different mole ratio (2.5, 5, 10, 25, 50, and 100% mole ratio relative to the HA repeating unit);

[0065] FIG. 9 depicts scanning electron microscope images of HA microparticles crosslinked with 5% DVS at different magnifications in 0.2M AOT-isooctane solution;

[0066] FIG. 10a depicts a graphical representation of weight loss (%) of HA particles crosslinked with DVS at different crosslinker ratios at 2.5 and 5 percent mole ratio relative to HA repeating unit;

[0067] FIG. 10b depicts a graphical representation of weight loss (%) of HA particles crosslinked with DVS at different crosslinker ratios at 10, 25, 50, and 100 percent mole ratio relative to HA repeating unit;

[0068] FIG. 11 depicts a graphical representation of the FT-IR spectra of Porous-HA (P-HA) and Modified-Porous-HA (M-P-HA) nanoparticles;

[0069] FIG. 12 depicts a graphical representation of a Ciprofloxacin release profile from Ciprofloxacin absorbed (A) and conjugated (C) HA microgels crosslinked with DVS at different crosslinker ratios at pH 7.4 in PBS at 37.5° C.

[0070] FIG. 13 depicts a graphical representation of a Vancomycin release profile from Vancomycin absorbed (A) and conjugated (C) HA particles crosslinked with DVS at different crosslinker ratios at pH 7.4 PBS at 37.5° C.

DETAILED DESCRIPTION OF EMBODIMENTS

[0071] The invention now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may however be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0072] It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present therebetween. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

[0073] It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, and/or section from another element, component, region, layer, and/or section.

[0074] It will be understood that the elements, components, regions, layers and sections depicted in the figures are not necessarily drawn to scale.

[0075] The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof

[0076] A “subject” or “patient” shall mean a human or animal including but not limited to a dog, cat, horse, cow, pig, sheep, goat, chicken, primate, fish, rat and mouse.

[0077] The compositions of the invention are administered in effective amounts. The term “effective amount” refers to the amount necessary or sufficient to realize a desired biologic effect. For example, an effective amount of a hyaluronic acid containing conjugate is that amount necessary to prevent or treat infection if the subject is being treated to prevent occurrence of an infection or inflammation.

[0078] As used herein, the term “treat” refers to a reduction or complete elimination of symptoms, such as but not limited to those associated infection or inflammation.

[0079] The effective amount for any particular application can vary depending on such factors as the disease or condition or location being treated, or the symptoms being alleviated, the particular conjugate being administered, the size of the subject, or the severity of the condition, or symptom. One of ordinary skill in the art can empirically determine the effective amount of a particular conjugate without necessitating undue experimentation.

[0080] As used herein, the term “simple carbohydrate” refers to monosaccharides, disaccharides, and includes, but is not limited to: sucrose, fructose, glucose, maltose, and lactose, as well as sugar alcohols.

[0081] Amounts that are described herein are idealized embodiments, but the range of acceptable amounts may be in a range of between 1% and 99%, or any subrange therein, including, but not limited to plus or minus 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% of values disclosed.

[0082] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0083] Exemplary embodiments of the present invention are described herein with reference to idealized embodiments of the present invention.

[0084] The invention provides novel compositions, methods of creation of novel compositions and treatment that would benefit from the presence of hyaluronic acid. Hyaluronic acid is known to permeabilize tissues and thus is useful for increasing the receptivity of a body tissue for another agent. The tissues so treated may be those that are under perfused either normally or due to a pathological state.

[0085] Native hyaluronic acid is a linear polymer of repeating monomers of disaccharides of D-glucuronic acid and N-acetyl D-glucosamine. As used herein, the term “hyaluronic acid” is intended to embrace native hyaluronic acid, as well as its derivatives (i.e., analogs) including but not limited to salts and esters, unless explicitly otherwise stated. Salts of hyaluronic acid include pharmaceutically acceptable salts such as sodium salts, potassium salts and ammonium quaternary salts. Hyaluronic acid derivatives include hyaluronic acid that has been modified by other chemical reactions such as esterification, and thus include hyaluronate esters, as well as sulfated hyaluronic acid (as described in U.S. Pat. No. 6,339,074 B1).

[0086] Hyaluronic acid is commercially available, and sold under a variety of brand names including Healon, Hyalastine, Hyalectin, Hyloran (sodium hyaluronate), and Hyaloftil (high molecular weight hyaluronic acid). Alternatively, hyaluronic acid can be synthesized or purified from animal sources.

[0087] Hyaluronic acid derivatives also include synthetic or semi-synthetic variants such as esters of hyaluronic acid and aliphatic, aromatic, araliphatic, heterocyclic, and cycloaliphatic alcohols (e.g., benzyl or ethyl ester of hyaluronic acid) as described in U.S. Pat. Nos. 4,851,521; 4,965,353; and 5,202,431).

[0088] As used herein, the term “conjugate” includes both direct and indirect attachment of the linking molecule to hyaluronic acid. Indirect attachment generally means that a spacer (i.e., a linker) exists between the linking molecule and the hyaluronic acid.

[0089] Conjugates may be attached to hyaluronic acid to the linking molecule by a bond that cleaves under normal physiological conditions. In still other instances, hyaluronic acid would be released in a sustained fashion, to prolong its release. Readily cleavable bonds include readily hydrolyzable bonds, for example, ester bonds, ether bonds, amide bonds and Schiff's base-type bonds.

[0090] Conjugates of hyaluronic acid with any number of linker molecules can deliver of a variety of therapeutic agents to a body tissue or surface. Hyaluronic acid is therefore intended to act as a carrier molecule for the therapeutic agent, and the hyaluronic acid itself may or may not impart therapeutic benefit. Examples of therapeutic agents that can be linked include: adrenergic agent; adrenocortical steroid; adrenocortical suppressant; alcohol deterrent; aldosterone antagonist; amino acid; ammonia detoxicant; anabolic; analeptic; analgesic; androgen; anesthesia, adjunct to; anesthetic; anorectic; antagonist; anterior pituitary suppressant; anthelmintic; anti-acne agent; anti-adrenergic; anti-allergic; anti-amebic; anti-androgen; anti-anemic; anti-anginal; anti-anxiety; anti-arthritic; anti-asthmatic; anti-atherosclerotic; antibacterial; anticholelithic; anticholelithogenic; anticholinergic; anticoagulant; anticoccidal; anticonvulsant; antidepressant; antidiabetic; antidiarrheal; antidiuretic; antidote; anti-emetic; anti-epileptic; anti-estrogen; antifibrinolytic; antifungal; antiglaucoma agent; antihemophilic; antihemorrhagic; antihistamine; antihyperlipidemia; antihyperlipoproteinemic; antihypertensive; antihypotensive; anti-infective; anti-infective, topical; anti-inflammatory; antikeratinizing agent; antimalarial; antimicrobial; antimigraine; antimitotic; antimycotic, antinauseant, antineoplastic, antineutropenic, antiobessional agent; antiparasitic; antiparkinsonian; antiperistaltic, antipneumocystic; antiproliferative; antiprostatic hypertrophy; antiprotozoal; antipruritic; antipsychotic; antirheumatic; antischistosomal; antiseborrheic; antisecretory; antispasmodic; antithrombotic; antitussive; anti-ulcerative; anti-urolithic; antiviral; appetite suppressant; benign prostatic hyperplasia therapy agent; blood glucose regulator; bone resorption inhibitor; bronchodilator; carbonic anhydrase inhibitor; cardiac depressant; cardioprotectant; cardiotonic; cardiovascular agent; choleretic; cholinergic; cholinergic agonist; cholinesterase deactivator; coccidiostat; cognition adjuvant; cognition enhancer; depressant; diagnostic aid; diuretic; dopaminergic agent; ectoparasiticide; emetic; enzyme inhibitor; estrogen; fibrinolytic; fluorescent agent; free oxygen radical scavenger; gastrointestinal motility effector; glucocorticoid; gonad-stimulating principle; hair growth stimulant; hemostatic; histamine H2 receptor antagonists; hormone; hypocholesterolemic; hypoglycemic; hypolipidemic; hypotensive; imaging agent; immunizing agent; immunomodulator; immunoregulator; immunostimulant; immunosuppressant; impotence therapy adjunct; inhibitor; keratolytic; LNRH agonist; liver disorder treatment; luteolysin; memory adjuvant; mental performance enhancer; mood regulator; mucolytic; mucosal protective agent; mydriatic; nasal decongestant; neuromuscular blocking agent; neuroprotective; NMDA antagonist; non-hormonal sterol derivative; oxytocic; plasminogen activator; platelet activating factor antagonist; platelet aggregation inhibitor; post-stroke and post-head trauma treatment; potentiator; progestin; prostaglandin; prostate growth inhibitor; prothyrotropin; psychotropic; pulmonary surface; radioactive agent; regulator; relaxant; repartitioning agent; scabicide; sclerosing agent; sedative; sedative-hypnotic; selective adenosine Al antagonist; serotonin antagonist; serotonin inhibitor; serotonin receptor antagonist; steroid; stimulant; suppressant; symptomatic multiple sclerosis; synergist; thyroid hormone; thyroid inhibitor; thyromimetic; tranquilizer; treatment of amyotrophic lateral sclerosis; treatment of cerebral ischemia; treatment of Paget's disease; treatment of unstable angina; uricosuric; vasoconstrictor; vasodilator; vulnerary; wound healing agent; xanthine oxidase inhibitor.

[0091] As will be apparent to one of ordinary skill in the art, these latter conjugates in which hyaluronic acid is used as a carrier for other therapeutic agents can be used in therapeutic or prophylactic methods for subjects in need of such therapeutics. It is within the realm of the medical practitioner to identify subjects that would benefit from administration of such agents.

Experiment 1: Controlled Rapid Release Drug Delivery system for Peri and Immediate Postoperative Infection Prophylaxis

[0092] An HA based antibiotic delivery system releases therapeutic levels of antibiotics in the peri and immediate postoperative period.

[0093] Antimicrobial activity and biocompatibility of Hyaluronic acid-conjugate polymer provides sufficient sustained release of antibiotic after ophthalmic surgery with equal efficacy as topical antibiotic therapy on pathogenic bacteria and does not cause significant toxicity to eukaryotic cells.

[0094] The following procedure was used to determine the efficacy and toxicity of an HA based antibiotic delivery system after ophthalmic surgery by evaluating the drug release rate of the HA-antibiotic polymer over time, the antimicrobial activity of the HA-antibiotic polymer over time, the biocompatibility of HA-antibiotic polymer in vitro on fibroblasts, and the corneal toxicity of the HA-antibiotic polymer.

[0095] Methods

[0096] Hyaluronic acid sodium salt from Streptococcus equi was purchased from Sigma Aldrich. Glycerol diglycidyl ether (GDE) (technical grade, Aldrich) as crosslinker, sodium bis(2-ethylhexyl) sulfosuccinate (AOT, 98%, Sigma-Aldrich) as a surfactant, and 2,2,4-trimethylpentane (isooctane) (ACS, Reag. Ph Eur, 99.5%) as a solvent, were used as received. 1,1′-carbonyldiimidazole (≥97%, Sigma-Aldrich) was as coupling agent. All the solvents, acetone (puriss., ≥99%, Sigma-Aldrich) and dimethyl sulfoxide (puriss., ACS reagent, ≥99.5%, Sigma-Aldrich) were of the highest purity available. Ultrapure distilled water 18.2 MΩ cm (Millipore-Direct Q UV3) was used throughout the studies. Ciprofloxacin (≥98%, HPLC grade, Sigma-Aldrich) and Vancomycin obtained from a local vender (≥98.0%, Mustafa Nevzat Pharmaceuticals, Turkey).

[0097] Synthesis of HA Particles

[0098] HA particles were synthesized as follows. Linear HA was dissolved in 0.2 M NaOH at a concentration of 50 mg/L. Then 1.08 mL of this HA solution was dispersed in 30 mL of 0.2 M AOT solution in isooctane. The mixture was immediately vortexed until a clear suspension was obtained. A certain amount of GDE (e.g., 50 mole percent relative to the HA repeating unit) was subsequently added to the mixture, which was then vortexed again to disperse the GDE. The reaction was allowed to proceed for 1 h at ambient temperature with vigorous stirring (1200 rpm). Then, the obtained particles were precipitated in excess of acetone and purified by centrifugation at 10,000 rpm for 10 min at 20° C. This was followed by removal of the supernatant solution and re-dispersal with acetone and re-centrifugation at least three times. The prepared particles were dried with a heat gun and kept in a closed container for further use.

[0099] Synthesis of HA:Sucrose Copolymeric Particles

[0100] HA:Sucrose (HA:Suc) copolymeric particles with DVS crosslinker were synthesized in a single step. Briefly, linear HA was dissolved in 0.2 M NaOH at a concentration of 50 mg/mL. Separately, 82 mg/mL concentration of sucrose solution was prepared the same mole ratio of HA repeating unit. Then, 1 mL of the HA solution and 0.5 mL of the sucrose solution was mixed, and 1 mL of this mixture was dispersed in 30 mL of 0.2 M AOT solution in isooctane. The mixture was immediately vortexed until a clear suspension was obtained. DVS (125 mole percent relative to the mixture materials repeating unit) as crosslinker was subsequently added to the mixture, which was then vortexed again to disperse the crosslinker. The reaction was allowed to proceed for 1 h at ambient temperature with vigorous stirring (1,000 rpm). Then, the obtained particles were precipitated in excess of acetone and purified by centrifugation at 10,000 rpm for 10 min at 20° C. This was followed by removal of the supernatant solution and re-dispersal with acetone and re-centrifugation at least three times. The prepared particles were dried with a heat gun and kept in a closed container for further use.

[0101] Synthesis of Ciprofloxacin/Vancomycin Conjugates Particles

[0102] Synthesis of Ciprofloxacin Conjugated Particles

[0103] HA and HA:Suc particles were conjugated with Ciprofloxacin. Shortly, 0.532 g of Ciprofloxacin were dissolved in 10 mL DMSO solution. Then, 0.286 g of 1,1′-carbonyldiimidazole was added to this solution and stirred at room temperature for 1 h. Subsequently, 0.84 g HA particles was added to the drug mixture and the reaction was allowed to react for 24 h at 80° C. under stirring. The conjugated HA particles was washed with DMSO one time and washed with acetone two times and dried with freeze dryer.

[0104] Synthesis of Vancomycin Conjugated Particles

[0105] HA and HA:Suc particles were conjugated with Vancomycin. Shortly, 0.42 g of Vancomycin were dissolved in 10 mL DMSO solution. Then, 0.286 g of 1,1′ carbonyldiimidazole was added to this solution and stirred at room temperature for 1 h. Subsequently, 0.84 g HA particles was added to the drug mixture and the reaction was allowed to react for 24 h at 80° C. under stirring. The particles were washed with DMSO one time and washed with acetone two times and dried with freeze dryer.

[0106] Drug Release Experiments

[0107] 30 μg of HA-antibiotic particles was placed into 1.5 mL Eppendorf tubes and 250-500 μL of Balanced Saline Solution (BSS) was added to the Eppendorf tubes and the mixture was vortex until well mixed. The drug mixture was then placed in a shaker at 37° C. and allowed to incubate.

[0108] At each time point e.g., 1 hour, 2 hour, 3 hour, 6 hour, 24 hour, 48 hour, 72 hour, 96 hour, 1 week, 2 week, 3 week and 4 week-, 50 μL of the mixture was removed and an equivalent volume of new BSS added back to the tubes. This was repeated each time a sample was removed for determination of drug release.

[0109] Measuring Released Amount of Drug

[0110] A standard curve was established using known concentrations of Ciprofloxacin and Vancomycin, and the absorbance values were measured at 275 and 280 nm, respectively, using the NanoDrop UV-Vis Spectrophotometer This was then plotted using Excel and a standard curve with equation established.

[0111] With each drug release collection, the Drop UV-Vis Spectrophotometer was used to measure the light absorbance, and the drug concentration then calculated using the previously established standard curve.

[0112] Antimicrobial Experiments

[0113] Antimicrobial activity of the released drug was tested on Pseudomonas aeruginosa and MRSA cultures and compared to standard concentrations of antibiotic using filter disks on Mueller Hinton plates. The released antibiotics or controls were added onto sterile filter discs (created using a standard hole punch on filter paper, autoclaved). One colony of each bacteria was selected and (pseudomonas or MRSA) placed into a bacteria culture tube and were incubated in 5 mL of LB broth and placed on 37° C. shaker for approximately 4-6 hours.

[0114] 500 μL of the incubated bacteria was then added to the Mueller-Hinton Plates (which have been acclimated to room temperature for at least 2 hours) and a plastic disposable spreader was used to carefully spread the bacteria broth onto the plates and allowed to settle for approximately 5-10 minutes. The filter discs were then placed on top of the bacterial plate and the plates inverted and placed in the 37° C. incubator overnight. After 24 hours, the plates were removed and the zones of inhibition measured and photographed. Parafilm was used to wrap around each plate to keep the plates at room temperature.

[0115] Cytotoxicity Experiments

[0116] 10.sup.5 smooth muscle cells were plated into each well of 12-well plates and allowed to settle for 1 hour in 2.5 mL of complete culture media (DMEM+10% FBS+antibiotics+amino acids). The cells were allowed to grow to 70-80% confluence. Meanwhile, various concentrations of HA-antibiotic conjugate, HA particles, and antibiotics were suspended in complete media and added to the wells. The cells were incubated at 37° C., 95% CO.sub.2 for 5 days. Following the incubation period, DMEM was removed cells were fixed in glutaraldehyde then stained with toluidine blue and resuspended in SDS. A cell counter was then used to quantify the absorbance of the stain to quantify and compare the number of cells in each group. The plates were photographed, then resuspended and then a UV spectrophotometer used to measure the light absorbance of the cell density.

[0117] Corneal Thickness

[0118] Human donor corneas were obtained from the Southern eye bank and suspected in optisol solution. The pachymetry was measured using a standard corneal pachymeter. 30 and 90 ug of HA-antibiotic was then added to the cornea in optisol and allowed to incubate for 5 days. After 5 days, the corneal pachymetry was again measure and the endothelial cells were observed under high magnification light microscopy.

[0119] Results

[0120] Rate of Drug Release of the Hyaluronic Acid-Ciprofloxacin and Hyaluronic Acid-Vancomycin Conjugate Polymer

[0121] The released amount of antibiotics (Ciprofloxacin and Vancomycin) from the conjugated HA-Ciprofloxacin particle was quantified using NanoDrop UV-Vis Spectrophotometer.

[0122] There was an immediate release of 130 mg of Ciprofloxacin per g of polymer every hour in the first 2 hours, followed by a fast release of 670 mg per g in the first 24 hours. The total released was 820 mg over 7 days. There was a linear trend of release. Similarly, there was an immediate release of 50-80 mg/g of Vancomycin in the first 2 hours, and a fast release of 230 mg per g of polymer in the first 24 hours. A similar linear rate of release is seen at 6 hours.

[0123] Antimicrobial Activity

[0124] Antimicrobial activity of the released drug was tested on Pseudomonas aeruginosa and MRSA cultures and compared to standard concentrations of Ciprofloxacin and Vancomycin, respectively, using filter disks on Mueller Hinton plates. The control studies show that only 5 μg of Ciprofloxacin, and 10 μg of Vancomycin is sufficient to inhibit pseudomonas and MRSA growth, respectively, and provide a zone of inhibition that is well above the MIC.

[0125] The released Ciprofloxacin and Vancomycin were able to provide sufficient inhibition of pseudomonas and MRSA growth, respectively at every time point of collection between 1 hour and 7 days (zone of inhibition up to 15 mm). After 1 weeks, the rate of drug release appeared to be too low for inhibition of bacterial growth.

[0126] The control studies show that only 10 μg of Vancomycin on a filter disc was sufficient to inhibit MRSA growth and provide a zone of inhibition of 8 mm. Published studies show that the minimum inhibitory concentration of Ciprofloxacin is 0.5 mg/L and Vancomycin is 2 mg/L. In 250 μL, the volume of the human anterior chamber, the amount of antibiotic released using the polymer was far in excess of the MIC. In addition, to simulate the constant outflow of aqueous humor and thus gradual decline in drug concentration in the eye, we removed 25% of the supernatant in the drug release collections each time we collected the sample and replaced with BSS, thus removing a significant amount of the drug each time, allowing antimicrobial testing using the actual change in drug concentration and not a cumulative effect. 20 mg of HA-Ciprofloxacin and 30 mg of HA-Vancomycin were sufficient and effective at preventing bacterial growth at every time point between 1 hour and 7 days, with zones of inhibition up to 15 mm and 12 mm, respectively

[0127] Cytotoxicity Studies

[0128] The HA-antibiotic polymers showed no effect on fibroblast cell proliferation over 5 days under normal culture conditions. The presence of HA polymers did not change the cell division or proliferation rates compared to control, where cells were cultured in the absence of any additional polymers.

[0129] Corneal Thickness Studies

[0130] The presence of HA-antibiotic polymers had no effect on corneal thickness over 5-day incubation period. FIG. 4 shows the optical microscopy imaged of HA particles crosslinked with GDE.

[0131] To confirm the conjugation of Ciprofloxacin (CP) to HA particles (CP-HA), FT-IR spectra of bare HA and CP-HA was recorded using FT-IR spectroscopy (Perkin Elmer Spectrum 100). The chemical structure of HA and CP and the specific peaks for bare HA were given as (a) and (b), respectively in FIG. 5. Specifically, FIG. 5a depicts the chemical structure of HA and CP, and FIG. 5b depicts FT-IR Spectra of bare HA particles, CP conjugated HA particles (CP-HA), and CP-HA particle after CP release in PBS at 37.5° C.

[0132] The released amount of drug from CP-HA conjugates were determined by UV-Vis spectrometer and the constructed graph is depicted in FIG. 6, which shows the CP release profile from CP-HA particle in phosphate buffer saline (PBS) at 37.5° C.

[0133] For the Vancomycin assay, a similar procedure was used to assess the Vancomycin HA combination, except the test bacteria was Staphylococcus aureus and similar results as above were produced (not shown).

[0134] Conclusion

[0135] The above experiment shows that surgical outcome and patient quality of life would be greatly improved by a fast drug releasing system that could be administered at time of ocular surgery and decrease risk of post-operative infections while also eliminating or minimizing the need for topical medications.

Experiment 2: HA: Sucrose Copolymeric Particles

[0136] Antimicrobial Studies

[0137] Four different bacteria; gram-positive Staphylococcus aureus ATCC 6538 and Bacillus subtilis ATCC 6633 and gram-negative Escherichia coli ATCC 8739 and Pseudomonas aeroginosa ATCC were cultured in different growing media separately. Certain amounts (40, 20, 10, 5, 2.5 mg) of HA particles, HA:Sucrose particles, Conjugated HA particles and HA:Sucrose particles with Ciprofloxacin and Vancomycin were put into 10 mL of nutrient broth and sterilized by irradiation with UV light at 420 nm for 2 min. Then, 0.1 mL of bacteria culture adjusted against McFarland 0.5 standard nearly 1×10.sup.8 CFU/mL were added to the growing media and incubated at 35° C. for 18-24 h. After then, 0.1 mL from the cultures in each medium were tube was placed on agar plate for enumeration of colonies. Minimum inhibition concentration (MIC) values was determined as the minimum concentration of antimicrobial material where no turbidity (visible growth) in NB medium. Minimum bactericidal concentration (MBC) values were determined as the lowest concentration of antimicrobial materials that can inhibit 99.9% of microorganisms.

[0138] As shown in FIG. 7, the presence of sucrose in HA-sucrose particles promotes or enhances B. Subtilis growth at 24, 48 72 h incubation time and enhances or do not affect S. aureus growth.

[0139] As shown in Table 1, for HA and HA-sucrose particles there are no MIC and MBC values for 24 h incubation time.

TABLE-US-00001 TABLE 1 Minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) values of HA particles and HA:Suc particles against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. HA particles MIC (mg/mL) MBC (mg/mL) Bacteria 1. 2. 3. 1. 2. 3. B. subtilis — — — — — — (Gram+) S. aureus — — — — — — (Gram+) E. coli — — — — — — (Gram−) P. aeruginosa — — — — — — (Gram−) HA:Suc particles MIC (mg/mL) MBC (mg/mL) Bacteria 1. 2. 3. 1. 2. 3. B. subtilis — — — — — — (Gram+) S. aureus — — — — — — (Gram+) E. coli — — — — — — (Gram−) P. aeruginosa — — — — — — (Gram−)

[0140] Upon testing the bacteria with Ciprofloxacin conjugated HA particles (HA-CP) and Ciprofloxacin conjugated HA-Sucrose particles there are MIC and MBC values at certain concentration of the particles as summarized in Table 2.

TABLE-US-00002 TABLE 2 Minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) values of Ciprofloxacin conjugated HA particles and Ciprofloxacin conjugated HA:Suc particles against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Ciprofloxacin conjugated HA particles MIC (mg/mL) MBC (mg/mL) Bacteria 1. 2. 3. 1. 2. 3. B. subtilis 0.25 0.25 0.25 — 1 0.5 (Gram+) S. aureus 2 2 2 4 2 2 (Gram+) E. coli >0.5 >0.5 >0.5 1 1 1 (Gram−) P. aeruginosa 0.25 0.25 0.25 0.5 0.5 0.5 (Gram−) Ciprofloxacin conjugated HA:Suc particles MIC (mg/mL) MBC (mg/mL) Bacteria 1. 2. 3. 1. 2. 3. B. subtilis 2 0.5 0.4 4 4 4 (Gram+) S. aureus 1 0.5 0.5 2 2 1 (Gram+) E. coli 0.5 <0.25 <0.25 1 0.25 0.25 (Gram−) P. aeruginosa 0.25 0.25 0.25 — 0.5 0.25 (Gram−)

Experiment 3: HA-Antibiotic System Suspended in Chitosan for Surface Application

[0141] One use for an HA-antibiotic delivery system suspending in chitosan is the ability of this system to adhere or form a viscous layer on tissue such as an eye. This system would be especially useful during cataract surgeries, where infections pose a significant problem. Current use of antibiotics on the eye require the use of antibiotic drops before, during, and after surgery. However, by using an HA-antibiotic chitosan suspension, the medical provider could add a drop of the solution and have a therapeutically effective amount of antibiotic release within approximately 4-6 hours, and have the antibiotic levels drop to below detectable levels (thereby preventing antibiotic resistance). Similar application of a HA-antibiotic chitosan suspension could be effective for joint spaces and other tissues.

[0142] Methods

[0143] Chitosan solution was prepared for HA suspension and preloaded into a spray nozzle system. 0.5 g chitosan was dissolved in 25 mL of 1% acetic acid solution in DI water and 100 mg conjugated HA-Ciprofloxacin particles are suspended into this chitosan solution. Then, chitosan coated HA-Ciprofloxacin particles were centrifuged at 10,000 rpm to separate from acetic acid solution. Finally, chitosan coated HA-Ciprofloxacin were resuspended in PBS or BBS at desired concentration. A photograph of the suspension of the HA-Ciprofloxacin conjugate with chitosan is shown in FIG. 3.

[0144] HA-Antibiotic conjugates (Vancomycin or Ciprofloxacin) should be added to the chitosan nozzle system and delivered to anterior segment portion of eye bank eyes (specifically, the cornea and conjunctival surface). These treated eye balls should be suspended in BSS Plus to mimic tears (1.5 cc) in a small sterile dish to mimic the tear film system. The BSS solution should replaced every day and assessed for the antibiotic concentration using HPLC analysis. This procedure should be repeated for 5 days followed by specular microscopy of the corneal endothelium (to study potential effects on corneal endothelium).

Experiment 4: Porous HA Particles

[0145] Materials and Methods

[0146] Materials

[0147] Sodium hyaluronate (HA-EP3, Bloomage Freda Biopharm Co. Ltd.) was used as received. Polyvinylpyrrolidone (PVP, average mol wt 40,000, Sigma Aldrich) as a porogen agent, divinyl sulfone (DVS) (98%, Merck), as crosslinker, sodium bis(2-ethylhexyl) sulfosuccinate (AOT, 98%, Sigma-Aldrich) as a surfactant, trimethylolpropane triglycidyl ether (TMPGDE) (technical grade, Aldrich) as a modifying agent were used as received. as solvent were used as received. All the solvents, 2,2,4-trimethylpentane (isooctane) (99.5%, Carlo Erba), isopropyl alcohol (IPA, puriss., meets analytical specification of Ph. Eur. ≥99.5 GC, Sigma Aldrich), acetone (99%, BRK), and ethanol (99%, Birkim) were used of the highest purity available. Ultra-pure distilled water 18.2 MΩ cm (Millipore-Direct Q UV3) was used throughout the studies.

[0148] Synthesis of HA Particles with Different Amounts Crosslinking Ratio

[0149] HA microparticles with different crosslinker degree of were synthesized according to the procedures reported previously with some modifications. Briefly, linear HA was dissolved in 0.2 M NaOH at a concentration of 30 mg/mL. Then, 1 mL of this HA solution was dispersed in 30 mL of 0.2 M AOT solution in isooctane. The mixture was immediately vortexed until a clear suspension was obtained. After 1 hour, different ratio of DVS as a crosslinker at 1, 2.5, 5, 10, 25, 50, 100 mol % relative to the HA repeating unit were added to the mixture, which was then vortexed again to disperse the crosslinker, separately. The reaction was allowed to proceed for 1 hour at ambient temperature with vigorous stirring (1,000 rpm). Then, the obtained particles were precipitated in excess of acetone and purified by centrifugation at 10,000 rpm for 10 min at 20° C. This was followed by removal of the supernatant solution and redispersal with acetone and water mixture and centrifugation at least five times. The prepared particles were swollen in DI water, dried with a freeze-dry and kept in a closed container for further use.

[0150] Characterization of HA Particles

[0151] Size and morphological characterization of the HA particles were visualized by using optic microscope (Olympus BX51) and scanning electron microscope (SEM Jeol JSM-5600 LV) instrument operating at 20 kV voltage. The certain amount of HA particles was placed on a carbon tape attached SEM stub and coated with a few nm thicknesses of gold under vacuum.

[0152] The dynamic light scattering (DLS) experiments were carried out at 90° angle detector using Brookhaven Ins. and Cor. 90 plus particle size analyzer, with 35 mW solid state laser detector operating at a wavelength of 658 nm. The results were the average values of consecutively ten measurements with an integration time of 2 seconds. Zeta potential measurements were conducted with Zeta-Pals Zeta Potential Analyzer BIC (Brookhaven Inst. Corp.) in 0.01 M KCl solution in water. Each measurement was repeated at least three times.

[0153] The functional groups of the HA particles were determined by using a Fourier Transform Infrared Radiation Spectroscopy (FT-IR, Perkin-Elmer) in the spectral range 4000-650 cm.sup.−1 at 4 cm.sup.−1 resolution using attenuated total reflectance (ATR). Thermal degradation of HA and HA particles were carried out using thermogravimetric analyzer (SII TG/DTA 6300, Japan). Nearly 5 mg of the materials was heated with 10° C./mL heating rate up to 1000° C. under inert atmosphere using N.sub.2 gas with 100 mL/min flow rate.

[0154] The specific surface areas, the pore volume and average pore width of the HA particles were performed by a Tristar II Surface Area and Porosity Analyzer using the Brunauer-Emmett-Teller (BET) and Barret-Joyner-Halenda (BJH) methods, respectively. For removed contaminants and wetness, HA particles were degassed by using a FlowPrep 060 Degasser at 100° C. for 5 h prior to adsorption analysis.

Results

[0155] Lower Amounts of DVS (<20 mole % of HA Repeating Unit) for Porous HA Particles

[0156] Hyaluronic Acid particles are synthesized according to the literature using divinyl sulfone as crosslinker DVS in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) isooctane microemulsion systems. In the literature, a minimum of 20 mole % DVS based on HA repeating unit is reported, and above this concentration of DVS usage result in nonporous HA microparticles.

[0157] Here, we report the use of DVS less then (<20 mole %) of based on HA repeating units that enable porous HA particles. Optical microscopy images as shown in FIG. 8, reveal that HA particles can be even prepared by using 2.5% DVS. It is clear that the HA particles prepared are spherical and the size ranges changes between few hundred nm to few hundred micrometers. Specifically, FIG. 8 depicts optical microscope images of HA microparticles crosslinked with DVS at different crosslinking mole ratios (2.5, 5, 10, 25, 50, 100% mole ratio based on the HA repeating unit).

[0158] The SEM images further illustrates the porous structure of HA particles as shown in FIG. 9, and revealed that HA particles using 5% DVS are porous. Specifically, FIG. 9 depicts scanning electronic microscope images of HA microparticles crosslinked with 5% DVS at different magnifications in 0.2 M AOT-isooctane solution.

[0159] Table 3 summarizes the Brunauer-Emmett-Teller (BET) (Micromeritics TriStar II) analysis result of HA particles prepared at different crosslinking ratio of DVS based on the HA repeating unit.

TABLE-US-00003 TABLE 3 Surface area, pore volume, and pore size of HA microparticles prepared at different crosslinking ratio, 2.5%, 5%, 10%, 25%, 50%, 100% using DVS as crosslinking agent based on the HA repeating unit. Surface area Pore volume Pore size Materials (m.sup.2/g) (cm.sup.3/g) (nm) 2.5% DVS 21.54 ± 10.31 4.51 ± 2.78 8.3 ± 1.7  5% DVS 14.33 ± 0.74  7.92 ± 1.40 8.2 ± 0.8  10% DVS 0.32 ± 0.27 0.86 ± 0.16 5.4 ± 2.6  25% DVS 0.00 ± 0.00 0.00 ± 0.00 0.0 ± 0.00 50% DVS 0.00 ± 0.00 0.00 ± 0.00 0.0 ± 0.00 100% DVS 0.00 ± 0.00 0.00 ± 0.00 0.0 ± 0.00

[0160] It is apparent from Table 3 that, the lower the crosslinking density, the higher the pore parameters such as surface area, pore volume and pore sizes. As the crosslinker ratio is increased to 20% or above HA particles become non-porous.

[0161] Hydrolytic Degradation of HA Microparticles

[0162] The hydrolytic degradation of HA microparticles that are prepared by using DVS as crosslinker at mole ratios (e.g., 2.5%, 5%, 10%, 25%, 50%, 100%) mole ratio of HA repeating unit was done at pH 7.4 at 37.5° C. For this purpose, 0.05 g of dried particles were placed in 50 mL of pH 7.4 buffer solutions at 37.5° C. with three replicates in a water shaker-bath under constant agitation. The degradation of HA particles (weight loss % of particles) was monitored for 30 days by collecting 0.5 mL of supernatant solution every second day and diluting with the corresponding buffer solution to 1.5 mL. All the experiments were performed in three replicates and the amount of degrading HA from the Ha particles were determined via HPLC using Thermo Ultimate 3000 HPLC system with refractive index (RI) detector containing rezex RNM-Carbohydrate Na.sup.+ column (5 μm, 300 mm×7.8 mm) of phenomenex via the following conditions: 0.8 mL/min flow rate, 65° C. temperature of column and 35° C. temperature of RI detector, 20 μL of injection volume for 10 min run time. Sulfuric acid solution (5 mM) was used as the mobile phase. For the calibrations of hyaluronic acid, the standard buffer solutions (eight different concentrations) were prepared in PBS solution at pH 7.4.

[0163] The degradation profile with time is given in FIGS. 10a and 10b. Specifically, FIG. 10a depicts weight loss (%) of HA particles crosslinked with DVS at different crosslinker ratios (2.5% and 5%), and FIG. 10b depicts weight loss (%) of HA particles crosslinked with DVS at different crosslinker ratios of 10, 25, 50, and 100 mole ratio of HA repeating unit. FIGS. 10a and 10b clearly reveal that up to 30 days degradation time in PBS at pH 7.4 at 37.5° C., HA particles prepared by using more 10% DVS crosslinking do not degrade whereas only about 35% of HA particle were found to degrade for 5% DVS crosslinked HA particles. On the other hand, HA particles prepared by using 2.5% DVS degrades almost linearly after 3 days.

Preparing HA Particles Using Higher Amounts of DVS (>25 mole % of HA Repeating Unit) in Presence of Porogen

[0164] To prepare porous HA nanoparticles with higher amounts of DVS (>25%) poly vinyl pyrrolidone (PVP) was used as porogen. PVP, 25% and 50% weight ratio of HA as a pore making agent (porogen) was used for HA particles that are prepared with DVS at 50 and 100% mole ratio of HA repeating unit. The PVP solution in DI water is prepared by dissolving 150 mg PVP (MW: 40 000 g/mol) in 1 mL DI water (15 weight %) and different amounts of this solution as 0.050-0.100 mL is dispersed in 30 mL of 0.2 M AOT solution in isooctane. The HA solution is prepared by dissolving HA (MW:1000 KDa) in 0.2 M NaOH at a concentration of 30 mg/mL (3 wt % HA) and 1 mL of this HA solution was added in 30 mL of 0.2 M AOT solution in isooctane under constant mixing at 1000 rpm. After 5 min, DVS as a crosslinker at different mole ratios e.g., 50, 100 mole % relative to the HA repeating unit were added to the mixtures, and then whole mixture was vortexed again to make homogenous dispersion. The reactions were allowed to proceed for 1 h at ambient temperature with vigorous stirring (1,000 rpm). Then, the obtained HA nanoparticles were precipitated by centrifugation at 10,000 rpm for 10 min at 20° C. This was followed by removal of the supernatant solution and dispersal with ethanol and was followed by removal of the supernatant solution and re-dispersal with acetone and water mixture and centrifugation at least five times. The prepared particles were swollen in DI water, dried with a freeze-dry and kept in a closed container for further use.

TABLE-US-00004 TABLE 4 Surface area, pore volume, and pore size of HA microparticles prepared with different crosslinking ratio of DVS as 50%, 100% and porous (P-) HA microparticles prepared with two concentration of polyvinylpyrolydone (PVP) (25% and 50% weight ratio of HA) which are crosslinked with DVS at 50% mole ratio of HA. Surface area Pore volume Pore size Materials (m.sup.2/g) (cm.sup.3/g) (nm) HA particles (50% 0.00 ± 0.00 0.00 ± 0.00  0.0 ± 0.00 DVS) HA particles (100% 0.00 ± 0.00 0.00 ± 0.00  0.0 ± 0.00 DVS) P-HA (25% PVP, 50% 21.47 ± 9.12  11.15 ± 2.11  8.4 ± 2.3 DVS) P-HA (50% PVP, 50% 1.61 ± 0.95 8.47 ± 1.06 12.8 ± 1.6  DVS) P-HA (25% PVP, 100% 8.71 ± 2.33 13.29 ± 4.85  7.6 ± 1.9 DVS) P-HA (50% PVP, 100% 0.014 ± 0.01  1.07 ± 0.94 9.9 ± 2.7 DVS)

[0165] It obvious from Table 4, the even non-porous HA particle with >25% mole DVS crosslinked can be made porous by using different and amounts of porogen materials such as PVP. The amounts and the MW of PVP (10 000-1 300 000) can varied to obtained HA particles with different porosity. Table 4 shows the BET analysis results of HA particles prepared with different amount of DVS crosslinker.

Experiment 5: Modification of HA Particles for Enhanced Functionality

[0166] Methods

[0167] For modification of HA nanoparticles, 200 μL of trimethylolpropane triglycidyl ether (TMPGDE) was placed in 5 mL of 0.2 M NaOH solution under 500 rpm mixing rate at room temperature. After 30 min, 200 mg of porous-HA (P-HA) particles was suspended into this mixture and reacted for 1 h more. These particles denoted as modified-HA (M-HA) particles was then precipitated in excess amount of ethanol and the particles was washed ethanol by centrifugation at 10,000 rpm for 10 min at 20° C. at least three times. M-P-HA nanoparticles was dried with heat gun and kept in a closed container for further use.

[0168] Upon modification, the number -OH functional groups on P-HA particle can be significantly increased. And these functional groups can increase the active agent, such as drugs, hormones, growth factor, peptide and proteins, etc., conjugation or attachments capabilities for delivery device applications. To corroborate the modification reaction, the Fourier Transform Infrared Radiation (FT-IR) spectra of HA particle before modification, (Porous-Hyaluronic Acid (P-HA)) and after modification (Modified-Porous-Hyaluronic acid (M-P-HA)) with TMPGDE was recorded and shown in FIG. 11.

[0169] It is apparent from FIG. 11 that the intensity of the stretching frequency of —OH functional groups between 3000-3500 cm.sup.−1 is significantly increased. Furthermore, the zeta potential measurements also further confirm the increase of the surface functionality upon TMPGDE modification of the HA particles. The zeta potential measurements of HA based particles are given in Table 5.

TABLE-US-00005 TABLE 5 Zeta potential measurement (mV) bare, porous (P-) and modified porous (M-P-) HA microparticles. Materials Zeta Potential (mV) HA microparticles −28.12 ± 2.54 P-HA microparticles −17.39 ± 1.31 M-P-HA microparticles −27.91 ± 1.27

[0170] As the zeta potential is directly related to the surface functionality of the particles, the increase of zeta potential from about 17 to about −27 mV clearly confirms the increase in the number of —OH functionality of HA particles. As non-porous HA particle possess about −28 mV seems higher than p-HA and M-P-HA particles also evidently shows that with the pore formation on particle surface some of the functionality embedded within the pores of the particles. Other modification agents such 3-Chloro-2-hydroxy-1-propanesulfonic acid to introduce —SO.sub.3H functionality, and 3-Chloropropylamine to introduce —NH.sub.2 functionality, 4-bromo butyronitrile to introduce —CN functionality, bromoacetic acid to introduce —COOH functionality, and bromo- or chloro-alkanes with different alkyl chain lengths such as Br(CH.sub.2).sub.nCH3 where n can be 1 to 17 can be readily used to modify HA and porous HA particles to render different physicochemical characteristics.

[0171] Ciprofloxacin Loading and Conjugation to Porous HA Particles

[0172] For conjugation (C) of HA particles with Ciprofloxacin, three crosslinker ratio of HA particles (2.5, 5, and 10% DVS) were used. In brief, 0.1266 g of Ciprofloxacin were dissolved in 10 mL dimethyl sulfoxide (DMSO), then, 0.068 g of 1,1′-carbonyldiimidazole was added to this solution and stirred at room temperature for 1 h. Subsequently, 0.2 g HA particles was added to the drug mixture and the reaction was allowed to react for 24 h at 80° C. under stirring. The conjugated HA particles was washed with DMSO one time and washed with acetone two times and dried in a freeze dryer.

[0173] For physical drug loading process (adsorption), 0.15 g dried HA particles was placed into 20 mL of DMSO solution containing 0.1 g Ciprofloxacin and stirred at room temperature. The particles were washed with DMSO one time and washed with acetone two times and dried with freeze drier.

[0174] In the Ciprofloxacin release studies, 50 mg of drug conjugated (C) and adsorbed (A) HA particles were dispersed in 1 mL of PBS at pH 7.4 and transferred to a dialysis membrane. The drug loaded particle containing membrane was put into 50 mL of PBS (pH 7.4) at 37.5° C. in a shaker bath. The drug containing solution in PBS was then taken and absorbance value at 270 nm in UV-Vis spectrometer was measured, and the released amount of Ciprofloxacin was determined from a previously determined drug calibration curve. The analysis was repeated for three times and depicted in FIG. 12, which shows the Ciprofloxacin release profile from Ciprofloxacin absorbed (A) and conjugated (C) HA microgels crosslinked with DVS at different crosslinker ratios at pH 7.4 in PBS at 37.5° C.

[0175] As can be seen from FIG. 12, the amounts of Ciprofloxacin release for porous HA particles depend on the pore structure, e.g., 2.5% DVS crosslinked HA particles have higher porosity and release higher amounts of drugs in comparison to 5 and 10% DVS crosslinked HA particles.

[0176] Vancomycin Loading and Conjugation Processes to Porous HA Particles

[0177] For Vancomycin conjugation (C) of HA particles, HA particles prepared by three crosslinker ratio e.g., 2.5, 5, and 10% DVS were used. In short, 0.1 g of Vancomycin were dissolved in 10 mL DMSO solution. Then, 0.068 g of 1,1′-carbonyldiimidazole was added to this solution and stirred at room temperature for 1 h. Subsequently, 0.2 g HA particles was added to the drug mixture and the reaction was allowed to react for 24 h at 80° C. under stirring. The Vancomycin conjugated HA particles were washed with DMSO one time and washed with acetone two times and dried with freeze drier.

[0178] For physical drug loading process (adsorption-A), 0.15 g dried HA particles was put into 20 mL of DMSO solution containing 0.1 g Vancomycin and stirred at room temperature. The particles were washed with DMSO one time and washed with acetone two times and dried with freeze drier.

[0179] For Vancomycin release studies, 50 mg of Vancomycin conjugated (C) and physically adsorbed (A) HA particles were dispersed in 1 mL of PBS at pH 7.4 and transferred to a dialysis membrane. Then this membrane was placed into 50 mL of PBS (pH 7.4) at 37.5° C. in a shaker bath. The drug containing solution in PBS was then sampled and the absorbance values was read via UV-Vis spectrometer at 280 nm, and the released amount of Vancomycin was determined from a previously constructed calibration. All the analysis was repeated for three times.

[0180] FIG. 13 demonstrates Vancomycin release profile of porous HA particles. As can be seen, the drug loading and release amount can be readily controlled by porosity of HA particles and the drug loading procedure. For example, 2.5 and 5% DVS crosslinked particles (loaded by conjugation) can release higher amounts of Vancomycin (up to 50 mg/g) for about 7 days whereas 10%DVS crosslinked particles (loaded by conjugation) release about 40 mg/g Vancomycin in about 7 days. Specifically, FIG. 13 depicts a Vancomycin release profile from Vancomycin absorbed (A) and conjugated (C) HA particles crosslinked with DVS at different crosslinker ratios at pH 7.4 in PBS at 37.5° C.

[0181] On the other hand, by using physically adsorbed drug loading process (A) into 10% DVS crosslinked HA particles, the release amount is significantly reduced, e.g., 20 mg/g in seven days. Therefore, the by choice of drug loading e.g., physical adsorption and chemical crosslinking and with the appropriate choice of porous HA particles, the release kinetic of active agent can be controlled in terms of amounts and time.

[0182] Anti-Fibrotic and Anti-Cancer Drug Loading into Porous HA Based Particles (Modified and Unmodified Porous HA Particles)

[0183] Porous HA particles and modified forms of porous HA particles can be loaded with some cancer medications such as Mitomycin C (MMC), 5-Fluorouacil (5-FU) and Cisplatin (CP). The loading of these drugs into HA based porous particles can be accomplished by means of physical adsorption where the interactions between the HA based particles and drugs can be hydrophilic interactions, hydrophobic interaction, dipole-dipole interaction or electrostatic interactions. As porous HA particles have higher surface area and higher porosity in comparison to non-porous HA particles, more drug molecules can be loaded into their porous network structure.

[0184] Predetermined amounts of drugs, MMC, 5-FU and CP etc. are dissolved in a suitable solvent such as DI water, methanol, ethanol, Dimethyl formamide (DMF), Dimethyl sulfoxide (DMSO) as is known the art to bring drugs into solution, and predetermined amount of porous HA particles or modified porous HA are then placed into one of these drug solutions (such as by soaking) under constant mixing between 100-1,000 rpm at room temperature in the dark. Depending on the extents of the porosity and the types of the functional groups that are generated on the modified porous HA particles, different amounts of drug molecule can be embedded within the porous of HA (or modified porous HA) particles. The interstices of porous HA polymeric chains can be filled with the desired amount of drug molecules with the desired drug types by the appropriate choice porosity of porous HA particles, the types of the used modifying and the choice of used solvent to imbibe the drug molecules into HA based porous particles. Depending on the concentration of the drugs within the pores of HA particles, the drug delivery systems can be used for different purpose, for example for MMC.

[0185] Different dosages of drugs can be loaded for different purposes. For example, anti-fibrotic low dose MMC can prevent scare tissue formation after glaucoma surgery, and to treat cancer high dose MMC can be used to target and kill cancer cells within the various parts of the body.

[0186] Interferons and Insulin Delivery with Porous HA and Modified Porous HA Particle

[0187] Porous HA and modified porous HA particles can also be used as carriers for delivering interferons and insulin to various parts of human body including human eyes. HA based particles can be loaded at desired amounts with interferons and insulin by placing dried HA based particles into the corresponding drug solutions in distilled water or phosphate buffer saline solution (PBS) or balanced salt solution or appropriate organic solvent. After centrifugation for separation of interferons and/or insulin loaded HA based particles, these drug loaded HA based particles can be used to prepare appropriate injectable formulations in water, PBS, or BBS. Furthermore, these drugs, such as interferons and insulin, can be chemically linked to HA based particles for the purpose of prolonged delivery into various parts of body, as these drugs have many functional groups such as —NH2, —COOH and —OH and —SH.

[0188] While the invention has been described in terms of exemplary embodiments, it is to be understood that the words that have been used are words of description and not of limitation. As is understood by persons of ordinary skill in the art, a variety of modifications can be made without departing from the scope of the invention defined by the following claims, which should be given their fullest, fair scope.