Gold nano-delivery system for pain and cancer therapy

Abstract

The present invention relates to development of a novel cannabinoid-based gold nanoparticle drug delivery system for intravenous or localized administration of cannabinoid drugs. More specifically, the gold nanoparticles with a specific size range are conjugated with various cannabinoid molecules (CBD and THC molecules) to synthesize a stable and biocompatible nano-delivery system suitable for both localized and intravenous administration.

Claims

1. A method of making a plurality of gold nanoparticles coated with a plurality of cannabinoids molecules (GNPs) for drug delivery, comprising the steps: a) preparing a gold salt HAuCl.sub.4 solution comprising a HAuCl.sub.4 in water; b) preparing a cannabinoid solution comprising of a cannabinoid in ethanol; c) preparing a mixture solution by adding the HAuCl.sub.4 solution to the cannabinoid solution; d) stirring the mixture solution so that a plurality of gold ions in the mixture solution interacts with the plurality of cannabinoid molecules; e) adding an aqueous solution of sodium borohydride (NaBH.sub.4) to the mixture solution to reduce the HAuCl.sub.4 to a metallic gold and to form a plurality of substantially spherical gold nanoparticles; f) adding a plurality of protective molecules to form a final solution of the plurality of substantially spherical gold nanoparticles coated with a plurality of protective molecules, and g) purifying the final solution.

2. The method of claim 1, wherein the HAuCl.sub.4 solution is 4 mM, the cannabinoid solution is 10 mM, and the mixture solution having the HAuCl.sub.4 ranges from 0.8 to 0.16 mM and the cannabinoid ranges from 0.75 to 1.0 mM, and 7.5 to 10 mM of sodium borohyrdide is added to the mixture solution.

3. The method of claim 2, wherein the mixture solution is stirred for 1-3 hours.

4. The method of claim 1, wherein the mixture solution has a concentration of the HAuCl.sub.4 ranges from 0.8 to 0.16 mM and the cannabinoid from 0.75 to 1.0 mM.

5. The method of claim 1, wherein the plurality of protective molecules are peptides, chitosan, dextran, hyaluronic acid, polyvinylpyrrolidone (PVP), or polyvinyl alcohol (PVA)).

6. The method of claim 1, wherein the plurality of protective molecules on the surface of the GNPs are between about 5 to 30 μM of protective molecule.

7. The method of claim 1, wherein the GNPs are less than 10 nm in diameter.

8. The method of claim 1, wherein the GNPs are in the range of 5-20 nm.

9. The method of claim 1, wherein the nanoparticles are water soluble.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments herein will hereinafter be described in conjunction with the appended drawings provided to illustrate and not to limit the scope of the claims, wherein like designations denote like elements, and in which:

(2) FIG. 1 shows a schematic of a gold nanoparticle coated with cannabinoid molecules;

(3) FIG. 2 shows the process of making of a gold nanoparticle with a first layer of cannabinoid molecule and a second layer of polymer coatings;

(4) FIG. 3 shows the process of making of a gold nanoparticle coated with a layer of cannabinoid molecule and sodium citrate;

(5) FIG. 4 shows a TEM image of gold nano particles coated with a hydrophobic drug;

(6) FIG. 5 shows the UV-Vis spectra of gold nanoparticles prepared by reduction of au salt with sodium borohydride in the presence of a hydrophobic drug molecule, and

(7) FIG. 6 shows the UV-Vis spectra of gold nanoparticles prepared by reduction of au salt with sodium citrate in the presence of a hydrophobic drug molecule.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(8) The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

(9) With respect to the above description, it is to be realized that the optimum relationships for the parts of the invention in regard to size, shape, form, materials, function and manner of operation, assembly and use are deemed readily apparent and obvious to those skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention.

(10) The present disclosure provides a method of making gold nanoparticles coated with cannabionoids molecules, as depicted in FIG. 1. Gold nanoparticles (GNP) are easy to design with small size and narrow distribution (5 to 20 nm spherical GNP), as such they can freely flow in blood capillaries without hindrance. They are also non-toxic as gold has been exploited for its medicinal properties for centuries.

(11) Gold nanoparticles have high surface to volume ratio, therefore, it is possible to have high payload of cannabinoid molecules on the surface. It is also possible to specifically attach numerous ligands, yielding multiple ligands localized on the material surface.

(12) The method 1, as shown in FIG. 2, comprises of the following steps: First a solution of pure cannabinoid is prepared in ethanol and then an aqueous solution of gold salt (HAuCl.sub.4) is added to it. The solution is stirred for 1 to 3 hours so all the gold ions interact with the cannabinoid molecules. This is followed by addition of freshly prepared aqueous solution of sodium borohydride NaBH.sub.4. In this process, reduction of gold ions by sodium borohydride (NaBH.sub.4) forms cannabinoid coated gold nanoparticles. Proper control of the concentration of the mixtures and proper timing generates spherical gold nanoparticles of less than 10 nm (FIG. 4) in size and coated with cannabinoid molecules. The particles are partially soluble in water.

(13) The method 2, shown in FIG. 3 comprises of the following steps: An aqueous solution of gold salt (HAuCl.sub.4) of about 4 mM is prepared. Similarly an aqueous solution of trisodium citrate is prepared in water (38.8 mM). The solution of cannabinoid is prepared in ethanol (10 mM). 1 ml of Au stock solution is mixed with 1 ml of trisodium citrate solution followed by addition of 40-80 micro liters of cannabinoid solution and the reaction is allowed to proceed at room temperature. In few hours a red color colloidal solution of colloidal gold is obtained which contains both cannabinoid and trisodium surface on to the surface. The solution is centrifuged and the pellet obtained is redissolved in Milli Q water. This removes any unreacted and free molecules in the solution. The particle size in this case is around 15-30 nm in size. These particles are freely soluble in water due to presence of citrate on the surface of gold together with cannabinoid.

(14) The prepared cannabinoid coated gold nanoparticles prepared by method 1 are purified by centrifuge method. The pellet obtained after centrifugation is mixed with a minimal quantity of ethanol or a mixture of water and ethanol solution. The concentrated solution thus obtained is then added dropwise to a 1% w/w of coating polymer like peptides, chitosan, dextran, hyaluronic acid, polyvinyl polyvinylpyrrolidone (PVP), or polyvinyl alcohol (PVA) under stirring as in Reference 1 where chitosan was coated on gold nanoflowers. Stirring is allowed to proceed for few hours to have homogenous coating. One layer of molecules coated with another layer of molecules. This coating process can be through a chemical reaction or by charge interaction. The additional layer of capping agent protects the cannabinoid molecules from external environment thus reducing their oxidation or binding with other molecules (blood proteins) if injected intravenously. The external polymer molecules provide extra stability to the system and also increases their solubility in water and the GNPs become stable in strong salt solutions and cell culture media. The organic coating on the gold nanoparticles will protect the cannabinoid molecules from ionic environment as well as interacting with blood proteins. The particles will become more hydrophilic with improved stability. The final concentration of gold by method 1 can be between 0.08-0.32 mM while the concentration of cannabinoid will range from 0.25-0.75 mM

(15) Water soluble polymers like Chitosan, PVP or PVA are, non-toxic polymer that binds at specific sites of lattice planes of gold nanoparticles thus providing them with extra stability. Therefore, the additional polymer layer makes the particles more hydrophilic and stable. Purification involves either dialysis or centrifuge methodology. Purification results in removal of any free molecules and ethanol.

(16) The active molecules on the surface of nanoparticles are confirmed mainly by IR and UV-vis studies. Nano-particles are fully characterized by various spectroscopic tools and Electron microscopy. This involves trial and error as we will have to try various stabilizing agents. The stability can be tested in salt solution and cell culture media.

(17) Shape, size and distribution change based on the concentration of the reactants as well as the reducing agent. Strong reducing agents tend to generate small particles while weak reducing agents tend to give large particles. FIG. 4 is TEM image of gold nanoparticles prepared by method 1. FIG. 5 is UV-Vis spectra of gold nanoparticles prepared by reduction with sodium borohydride. The plasmon band at 500 nm is proof of small particles of around 5 nm. In order to obtain monomodal distribution of spherical shaped gold nanoparticles, specific concentrations have to be used.

(18) Cannabinoid loaded gold nanoparticles prepared by method 2 can also be loaded by other molecules for drug delivery. For example in reference 2 molecules like 11-mercaptoundecanoid acid (MUA), glucose oxidase (GOx) (enzyme) could also be added to this system due to presence of sodium citrate on the surface of gold nanoparticles. MUA-AuPVP NPs) in reference 2 were produced via ligand exchange reaction between citrate and MUA under the protection of PVP/citrate while GOx was added to MUA-AuPVP NPs by EDC-NHS coupling protocol.

(19) Functionalization can be easily confirmed by techniques like ATR_FTIR and XPS. The addition of these molecules can be initially visualized by UV-vis spectroscopy which can display shift of plasmon band indicating formation of additional layers of these active molecules on the nanoparticle surface. Further characterization can be carried out by techniques like ATR-FTIR, NMR and XPS spectroscopy.

(20) The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

(21) With respect to the above description, it is to be realized that the optimum relationships for the parts of the invention in regard to size, shape, form, materials, function and manner of operation, assembly and use are deemed readily apparent and obvious to those skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention.

REFERENCES

(22) 1—A. Jakhmola, R. Vecchione, F. Gentile, M. Profeta, A. C. Manikas, E. Battista, M. Celentano, V. Onesto, P. A. Netti, Experimental and theoretical study of biodirected green synthesis of gold nanoflowers. Materials Today Chemistry 2019 (in press), https://doi.org/10.1016/j.mtchem.2019.100203 2—M. Celentano, A. Jakhmola, M. Profeta, E. Battista, D. Guarnieri, F. Gentile, P. A. Netti, R. Vecchione, Diffusion limited green synthesis of ultra-small gold nanoparticles at room temperature, Colloids Surfaces A Physicochem. Eng. Asp. 558 (2018) 548-557, https://doi.org/10.1016/j.colsurfa.2018.09.030