CARBON QUANTUM DOT, A COMPOSITION THEREOF AND A METHOD FOR TREATING INFECTION BY USING SAME

Abstract

Provided is a carbon quantum dot having a graphite core and a surface including components, such as compounds derived from formula (I) and halogens, and having a positive charge for antibacterial purposes. Also provided are methods for preparing a carbon quantum dot and a composition containing the same.

Claims

1. A carbon quantum dot comprising a reaction product derived from a compound of formula (I) and a halide ion compound after a pyrolysis treatment: ##STR00016## wherein the reaction product comprises a graphite core and a surface having a compound of formula (I) and a halogen, and the surface has a positive charge.

2. The carbon quantum dot according to claim 1, wherein R.sub.1 in the compound of formula (I) is selected from the group consisting of C.sub.2-C.sub.8 alkyl, C.sub.7 alkylamine, C.sub.10 alkyl polyamine, 2-pentanol group and sulfide group.

3. The carbon quantum dot according to claim 1, wherein the halogen is derived from a chlorine compound, a bromine compound, or an iodine compound.

4. The carbon quantum dot according to claim 3, wherein the chlorine compound is hydrogen chloride, ammonium chloride, hypochlorous acid, potassium chloride, or sodium chloride.

5. The carbon quantum dot according to claim 3, wherein the bromine compound is hydrogen bromide or potassium bromide.

6. The carbon quantum dot according to claim 3, wherein the iodine compound is hydrogen iodide or potassium iodide.

7. A method for preparing the carbon quantum dot according to claim 1, comprising: mixing the compound of formula (I) with the halide ion compound to form a mixture: ##STR00017## and pyrolyzing the mixture at a temperature to obtain the carbon quantum dot.

8.-12. (canceled)

13. The method according to claim 7, wherein the temperature is between 150° C. and 300° C.

14. The method according to claim 13, wherein the temperature is between 150° C. and 180° C., between 180° C. and 210° C., between 210° C. and 240° C., between 240° C. and 270° C., or between 270° C. and 300° C.

15. An antibacterial composition comprising the carbon quantum dot according to claim 1 and a pharmaceutically acceptable carrier thereof.

16.-21. (canceled)

22. The antibacterial composition according to claim 15, wherein the halogen has a weight percentage of between 15% and 40% in the antibacterial composition.

23.-34. (canceled)

35. The antibacterial composition according to claim 15, wherein the carbon quantum dot has a diameter of from 1 nm to 8 nm.

36. The antibacterial composition according to claim, wherein the carbon quantum dot has a positive surface charge of from 38 mV to 48 mV zeta potential.

37. The method according to claim 40, wherein the infective condition or disease is caused by proliferation of a microorganism selected from the group consisting of a non-multidrug resistant bacterium, a drug resistant bacterium and a multidrug resistant bacterium.

38. The use method according to claim 37, wherein the non-multidrug resistant bacterium is selected from the group consisting of E. coli, P. aeruginosa, S. enterica, S. aureus, S. inus, and C. albicans.

39. The carbon quantum dot according to claim 1, wherein R.sub.2 is selected from the group consisting of H and carboxyl group.

40. A method for treating an infective condition or disease, comprising administering an effective amount of the carbon quantum dot according to claim 1 to a subject in need thereof.

41. The method according to claim 37, wherein the multidrug resistant bacterium is drug-resistant Staphylococcus.

Description

BRIEF DESCRIPTIONS OF THE DRAWINGS

[0046] FIG. 1 shows the differences in the antibacterial effects of the carbon quantum dots (CQDs) compound of formula (I) and the chlorine-containing carbon quantum dot derivatives thereof.

[0047] FIG. 2 is a schematic diagram showing the differences in the detected inhibitory effect on Escherichia coli (E. coli) of carbon quantum dot derivatives of 1,6-hexanediamine with different chlorine contents in the structure.

[0048] FIG. 3 shows the efficacy data of the detection of the chlorine-containing carbon quantum dot derivatives of 1,6-hexanediamine on the inhibition of different bacterial strains.

[0049] FIG. 4 is a schematic diagram showing detection of the antibacterial ability of three halogen-containing carbon quantum dot derivatives of 1,6-hexanediamine.

[0050] FIGS. 5A to 5D are diagrams of plating for detecting the antibacterial ability of three halogen-containing carbon quantum dot derivatives of 1,6-hexanediamine.

[0051] FIGS. 6A and 6B show the results of a high-resolution electron microscopy (HR-TEM) analysis of the chlorine-containing carbon quantum dot derivatives of 1,6-hexanediamine (FIG. 6A) and the chlorine-containing carbon quantum dot derivatives of spermidine (FIG. 6B).

[0052] FIGS. 7A and 7B are the detection results of the structural composition using laser desorption/ionization mass spectrometry to analyze the surfaces of the chlorine-containing carbon quantum dot derivatives of spermidine (FIG. 7A) and the chlorine-containing carbon quantum dot derivatives of 1,6-hexanediamine (FIG. 7B).

[0053] FIG. 8 is a structural diagram of the carbon quantum dots of the present application. In FIG. 8, 1 represents a halogen compound; 2 represents a compound of formula (I); 3 represents a positive charge; and 4 represents graphite core.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] 1. Carbon Quantum Dot (CQD) Synthesis Method

[0055] A variety of polyamines and polyamine derivatives with the structural characteristics of the compound of formula (I) (as shown in Table 1 below) were mixed with halogen-containing compounds (as shown in Table 2 below) as precursors, and subject to pyrolysis (as described in the experimental method in Taiwan Patent No. 1648003, with different high temperature combinations) to form carbon quantum dots. After the obtained solid was naturally cooled to room temperature, deionized water was added thereto. The mixture was ultra-sonicated for 1 hour, and then centrifuged using a high-speed centrifuge at a relative centrifugal force (RCF) of 500×g for purification, and then the supernatant was taken out. The supernatant was purified by dialysis and then freeze-dried into carbon quantum dots. The detailed structural and compositional analysis methods of carbon quantum dots include: nanometer particle size and interface potential measuring instrument, element analyzer, inductively coupled plasma mass spectrometer, high resolution electron microscope, and laser desorption/ionization mass spectrometry.

TABLE-US-00001 TABLE 1 Compounds of Formula (I) No. Name Structure [00005] A 1,2-diamino- ethane [00006] R.sub.1 = [CH.sub.2].sub.2 R.sub.2 = H B 1,4-diamino- butane [00007] R.sub.1= [CH.sub.2].sub.4 R.sub.2 = H C 1,6-diamino- hexane [00008] R.sub.1 = [CH.sub.2].sub.6 R.sub.2 = H D 1,8-diamino- octane [00009] R.sub.1 = [CH.sub.2].sub.8 R.sub.2 = H E spermidine [00010] R.sub.1 = [CH.sub.2].sub.4—NH—[CH.sub.2].sub.3 R.sub.2 = H F spermine [00011] R1 = [CH.sub.2].sub.3—NH—[CH.sub.2].sub.4—NH—[CH.sub.2].sub.3 R2 = H G 2,6-diamino- hexanoic acid [00012] R1 = [CH.sub.2].sub.4—CH—COOH R2 = H H 2,6-diamino-5- hydroxy- hexanoic acid [00013] R.sub.1 = CH.sub.2—CHOH—[CH.sub.2].sub.2—CH—COOH R.sub.2 = H I 2-amino-3-(2- amino- ethylsulfanyl)- propionic acid [00014] R.sub.1 = [CH.sub.2].sub.2—S—CH.sub.2—CH—COOH R.sub.2 = H

TABLE-US-00002 TABLE 2 Halogen-containing compounds No. Name of halogen-containing compound Type of halogens added 0 No addition No addition 1 Hydrogen chloride (HCl) Chlorine (Cl) 2 Ammonium chloride (NH.sub.4Cl) 3 Hypochlorous acid (HClO) 4 Potassium chloride (KCl) 5 Sodium chloride (NaCl) 6 Hydrogen bromide (HBr) Bromine (Br) 7 Potassium bromide (KBr) 8 Hydrogen iodide (HI) Iodine (I) 9 Potassium iodide (KI)

[0056] In some embodiments, the compounds of formula (I) shown in Table 1 and the halogen-containing compounds shown in Table 2 were used as precursors, and a pyrolysis process was performed at the following temperature to produce various carbon quantum dots:

TABLE-US-00003 TABLE 3 Precursor composition and pyrolysis temperature of various carbon quantum dots in the examples Precursor of Precursor of Halogen- Temperature of Code of Carbon Compound of containing pyrolysis Quantum Dot Formula (I) compound (° C.) A0 1,2-diaminoethane — 270 B0 1,4-diaminobutane — 270 C0 1,6-diaminohexane — 270 D0 1,8-diaminooctane — 240 E0 spermidine — 270 F0 spermine — 270 G0 2,6-diaminohexanoic — 280 acid H0 2,6-diamino-5- — 280 hydroxyhexanoic acid I0 2-amino-3-(2-amino- — 280 ethylsulfanyl)- propionic acid A1 1,2-diaminoethane HCl 270 B1 1,4-diaminobutane HCl 270 C1 1,6-diaminohexane HCl 270 D1 1,8-diaminooctane HCl 240 E1 spermidine HCl 270 F1 spermine HCl 270 G1 2,6-diaminohexanoic HCl 280 acid H1 2,6-diamino-5- HCl 280 hydroxyhexanoic acid I1 2-amino-3-(2-amino- HCl 280 ethylsulfanyl)- propionic acid C1-0.5 1,6-diaminohexane 0.5X HCl 270 C1-2 1,6-diaminohexane 2X HCl 270 C1-4 1,6-diaminohexane 4X HCl 270 C1-6 1,6-diaminohexane 6X HCl 270 C2 1,6-diaminohexane NH.sub.4Cl 270 C3 1,6-diaminohexane HClO 270 C4 1,6-diaminohexane KCl 270 C5 1,6-diaminohexane NaCl 270 C6 1,6-diaminohexane HBr 270 C7 1,6-diaminohexane KBr 270 C8 1,6-diaminohexane HI 270 C9 1,6-diaminohexane KI 270

[0057] 2. Antibacterial Test of Carbon Quantum Dots

[0058] The minimum inhibitory concentration (MIC) value of a carbon quantum dot was determined by a standard dilution method in a variety of tested bacterial strains, including E. coli (Escherichia coli), P. aeruginosa (Pseudomonas aeruginosa), S. enteritidis (Salmonella enterica), S. aureus (Staphylococcus aureus), MRSA (Methicillin-resistant Staphylococcus aureus, a multi-drug resistant Staphylococcus), S. iniae (Streptococcus iniae), and C. albicans (Candida albicans).

[0059] Growth and Determination of Bacteria

[0060] A single colony of each strain was removed from the culture medium, and inoculated in each suitable growth medium (10 mL). The cultured bacteria were grown at 37° C. with shaking (200 rpm), until the absorbance at 600 nm (O.D. 600) reaches 1.0 (optical path length: 1.0 cm). Each cell mixture was centrifuged at 1.0 mL (RCF 3,000×g, 10 mM, 25° C.), and washed twice with 5 mM sodium phosphate buffer (pH 7.4) before further use. The carbon quantum dots were mixed with a 10.sup.5 CFU/mL bacterial solution, and the final concentration of the reaction bacterial solution was 10.sup.4 CFU/mL. After reaction for 3 hours, each suitable growth medium was added. After 12 hours of incubation in the incubator at the culture temperature of each strain, the absorbance at 600 nm (O.D. 600) was measured.

[0061] In one embodiment, the differences in the antibacterial effect of the carbon quantum dots A0 to I0 and the corresponding halogen-containing carbon quantum dots A1 to I1 in Table 3 were detected. The results are shown in FIG. 1. FIG. 1 shows that the carbon quantum dots made of mixed chlorine compounds as precursors obviously had better antibacterial ability.

[0062] In some embodiments, the compound of formula (I) and halogen were mixed at different molar ratios of 1:0.5, 1:1, 1:2, 1:4 or 1:6 to form precursors, and they were prepared separately as the carbon quantum dots with different halogen contents. Then, the weight percentages of the halogens in the compositions of the carbon quantum dots were analyzed. Table 4 shows the detection of 1,6-hexanediamine (compound C of formula (I) in Table 1) and hydrogen chloride in different proportions as precursors to prepare carbon quantum dots, like C1-0.5, C1, C1-2, C1-4 and C1-6 in Table 3, wherein weight percentages of chlorine in the entire carbon quantum dot compositions were shown in Table 4. It can be seen that the more halogen compounds added to the precursor, the more halogens will be contained in the final structures of carbon quantum dots.

TABLE-US-00004 TABLE 4 Weight percentage of chlorine in the structure of the chlorine- containing carbon quantum dot derivatives of 1,6-hexane diamine Elemental composition (mass ratio) Code of carbon quantum dot Chlorine (%) C0 N/A C1-0.5 18.24 C1 28.68 C1-2 27.54 C1-4 35.07 C1-6 37.40

[0063] In some embodiments, the antibacterial effects of carbon quantum dots with different chlorine contents in the structures were tested. FIG. 2 is a schematic diagram of the detection of the differences in the inhibitory effect on E. coli (Escherichia coli) by carbon quantum dot derivatives having different chlorine contents in the structures, as prepared by 1,6-hexanediamine (compound C of formula (I) listed in Table 1) and different ratios of hydrogen chloride as precursors. FIG. 2 shows that as long as the final carbon quantum dot structure had a certain amount of halogen, the ability to inhibit the growth of bacteria can bring about unexpected and notable progress.

[0064] In some embodiments, the following seven strains were used: E. coli (Escherichia coli), P. aeruginosa (Pseudomonas aeruginosa), S. enteritidis (Salmonella enterica), S. aureus (Staphylococcus aureus), MRSA (Methicillin-resistant Staphylococcus aureus, a multi-drug resistant Staphylococcus), S. iniae (Streptococcus iniae), and C. albicans (Candida albicans), and the data for testing the antibacterial effect of carbon quantum dot derivatives were shown in FIG. 3. FIG. 3 shows the efficacy data of the detection of carbon quantum dots with 1,6-hexanediamine as the precursor (C0 carbon quantum dot in Table 3) and the corresponding chlorine-containing carbon quantum dots (C1 carbon quantum dot in Table 3) for different strains. FIG. 3 shows that the halogen-containing C1 carbon quantum dot had a significantly better effect on the antibacterial ability of the above-mentioned bacteria than the halogen-free C0 carbon quantum dot in the composition.

[0065] In some embodiments, the antibacterial ability of the carbon quantum dots of the compounds of formula (I) containing different halogens against E. coli was tested respectively, and the results were shown in FIG. 4. FIG. 4 is a schematic diagram of detecting the antibacterial ability of the carbon quantum dots prepared with 1,6-hexanediamine (compound C of formula (I) in Table 1) and three halogen-containing compounds (Table 2) as precursors. FIG. 4 shows that the uncarbonized compound of formula (I) had the worst antibacterial effect. As compared with the uncarbonized compound, the carbon quantum dot of the compound of formula (I) (C0 carbon quantum dot in Table 3) had a better antibacterial ability. The carbon quantum dots of the compounds of formula (I) containing halogens (C2, C7 and C8 carbon quantum dots in Table 3), such as chlorine, bromine or iodine, in the structure can increase the antibacterial ability by more than 10 folds.

[0066] In some embodiments, the antibacterial abilities of the carbon quantum dots of the compounds of formula (I) containing different halogens on E. coli were detected, respectively, and the results of the colony growth effect after plating were shown in FIGS. 5A to 5D. FIGS. 5A to 5D show the effect of antibacterial abilities by plating of the halogen-free C0 carbon quantum dot and the halogen-containing C3, C6 and C9 carbon quantum dots in Table 3. FIGS. 5A to 5D show that the carbon quantum dots containing halogens, like chlorine, bromine or iodine, in the structure bring about an unexpected, significant antibacterial effect over the same type of carbon quantum dots free from containing halogens.

[0067] In some embodiments, the structure of the carbon quantum dot of the compound of formula (I) containing halogen was analyzed by a high-resolution transmission electron microscopy (HR-TEM). FIG. 6A shows the C1 carbon quantum dot listed in Table 3, and FIG. 6B shows the E1 carbon quantum dot listed in Table 3. These central parts of the carbon quantum dots of the compounds of formula (I) containing halogen had (002) and (100) graphite lattice planes, showing that the common structural feature is the graphite core of carbon quantum dots of formula (I) compounds containing halogen.

[0068] In some embodiments, laser desorption/ionization mass spectrometry (LDI-MS) was used to analyze the structure of the carbon quantum dots of the compounds of formula (I) containing halogen. The surface of the carbon quantum dot was impinged with laser, which may cause the surface functional groups to be freed, and thereby generating a mass spectrometry signal. FIG. 7A shows the C1 carbon quantum dot in Table 3, and FIG. 7B shows the analysis result of the E1 chlorine-containing carbon quantum dot in Table 3. Compound C and compound E can be freed by laser from the C1 and E1 carbon quantum dots, respectively, showing that the compounds of formula (I) polymerized on the surface is a common technical feature of carbon quantum dots of the compounds of formula (I) containing halogen.

[0069] In some embodiments, a dynamic light scattering/Zeta potential analyzer (DLS & zeta potential), an elemental analyzer, and an inductively coupled plasma mass spectrometer (ICP-MS) were used to analyze the structures of the compounds of formula (I) and the structures of the carbon quantum dots prepared by using the compounds of formula (I) as the precursor alone or by mixing the compound of formula (I) with the halogen-containing compounds as the precursors. Table 5 below shows the comparison results of the particle size, potential and the elemental content (oxygen, nitrogen, carbon, hydrogen, and halogen) in the component of uncarbonized compound C of formula (I), halogen-free C0 carbon quantum dot, and C1, C6, and C8 carbon quantum dots containing chlorine, bromine, and iodine, respectively. It can be observed that the structural components of the three halogen-containing carbon quantum dots (C1, C6, and C8) of compound C of formula (I) all carry halogen atoms as precursors, and the surface of the structures each has a net positive charge.

TABLE-US-00005 TABLE 5 Particle size, potential, and content of elements (oxygen, nitrogen, carbon, hydrogen, and halogen) in the structure of three halogen-containing polyamine carbon quantum dot derivatives of 1,6-hexanediamine Diameter Zeta potential Elemental composition (mass ratio) (nm; n = 5) (mV; n = 5) Oxygen (%) Nitrogen (%) Hydrogen (%) Carbon (%) Halogen (%) C N/A N/A N/A 24.2 62.3 13.5 N/A C0 3.9 ± 1.2 37.4 ± 1.5 15.9 20.7 50.1 13.5 N/A C1 2.3 ± 0.6 43.2 ± 1.7 5.3 15.8 39.1 10.7 29.1 C6 2.4 ± 0.7 45.2 ± 2.7 4.9 13.6 35.4 9.5 36.6 C8 5.5 ± 1.7 42.4 ± 3.7 5.4 14.2 44.6 10.6 25.2

[0070] In some embodiments, the carbon quantum dots of the compounds of formula (I) containing halogen were applied to the anti-infective effects of animals, and grouper farming was taken as an example herein. One mg of a halogen-containing C1 carbon quantum dot in Table 3 was added to 1 kg of feed, and mixed evenly for feeding two-inch grouper fry. After feeding for 7 consecutive days, a challenge test (the challenge strain was Vibrio campbellii (V. campbellii)) was performed. The grouper was soaked in 10.sup.6 CFU/mL V. campbellii for 1 hour and 30 minutes, before moving to normal environment to observe the survival rate thereof. Table 6 shows the results of three independent experiments, confirming that feeding the carbon quantum dots of the compounds of formula (I) containing halogen have no effect on the health of grouper, and also effectively increase the survival rate of grouper by 1.5 to 4 folds under severe bacterial infection.

TABLE-US-00006 TABLE 6 The results of an animal efficacy test of the chlorine-containing carbon quantum dot derivatives of 1,6-hexanediamine Survival rate (%) Control group C1 First-batch Test 20 80 Second-batch Test 58 83 Third-batch Test 40 85

[0071] FIG. 8 is a schematic diagram of the structure of the carbon quantum dot of the present application, which is a reaction product derived from a compound of formula (I) and a halide ion compound after a pyrolysis treatment:

##STR00015##

The reaction product comprises a graphite core and a surface having a compound of formula (I) and a halogen, and the surface has a positive charge.

[0072] The embodiments described in this application include the product or process that a member of the group is exhibited in, is used in, or is related to. The numerous embodiments contained in the present application include more than one or all of the group members exhibited in, used in, or related to the product or process.

[0073] In addition, it should be noted that the present application relates to carbon quantum dots of the halogen-containing compounds of formula (I) prepared by using the compounds of formula (I) and the halogen compounds as precursors, and the synthesis precursors, halogen sources, synthesis methods, and the final structure and characteristics of the carbon quantum dots are different from those of the prior art. It is also found from the examples of the present application that containing halogens in the structures of the carbon quantum dots of the compounds of formula (I) brings about an unexpected, significantly enhanced antibacterial effect. In addition, compared with the previous antibacterial carbon quantum dots, the carbon quantum dots of the present application have been proven to have various unexpected, significant advantages, including better antibacterial ability that can be applied to the disease prevention and treatment of sea grouper and can be used against the fungus Candida albicans, etc. In some embodiments, the chlorine-containing carbon quantum dot of 1,6-hexanediamine (compound C of formula (I) in Table 1) (C1 carbon quantum dot in Table 3) has a minimum inhibitory concentration as low as 0.0001 mg/mL in E. coli.

[0074] A person having ordinary skill in the art will use no more than conventional experiments to identify or ascertain many equivalent embodiments of the present disclosure. The (protection) scope of the present application is not limited to the embodiments disclosed, but also includes all the embodiments fallen within the scope of the appended claims. In addition, it can be understood that the equipment, conditions or materials can be modified as suitable for the teaching of the present application, without departing from the scope thereof.