Bactericides and antifungal agents

Abstract

Disclosed are a composition containing a transition metal, as well as a method of treatment of bacterial, or of fungal diseases using such composition. The composition functions as novel bactericides and antifungal agents. The transition metal may be in either soluble or insoluble form.

Claims

1. Method of treatment of bacterial, or of fungal diseases, comprising administrating a transition metal in insoluble form to a patient in need thereof, wherein the transition metal in insoluble form is in the form of a transition metal with oxidation state 0 or in the form of a sulfide or a transition metal oxide, wherein the transition metal is selected from the group consisting of copper, silver and gold, wherein said transition metal in insoluble form is put into aqueous solution by the formation of nanoparticles by adding surfactant, and wherein said transition metal is contained in a structure consisting of a core containing said transition metal, surrounded by a surfactant shell.

2. The method according to claim 1, wherein the bacterial disease is acne.

3. The method according to claim 1, wherein the surfactant is selected from an RX, X being a derived radical of a mineral or organic acid, or NO.sub.3.sup.−, SO.sub.4.sup.−, CH.sub.3COO.sup.−, or X being a halogen or other acidic radical, R being a C1-C20 alkyl trimethylammonium, or wherein said surfactant is cetyltrimethylammonium or octyltrimethylammonium, a polyethylene glycol, or polyethylene glycol-dithiol.

4. The method according to claim 1, wherein the transition metal is in a composition containing water, or a composition containing water comprising in the order of 1 to 200 mg of transition metal per liter of composition.

5. The method according to claim 1, wherein the transition metal is in a composition containing water, or a composition containing water comprising in the order of 1 to 200 mg of transition metal per liter of composition, wherein the water-containing composition is an aqueous solution.

6. The method according to claim 1, wherein the transition metal is in a composition containing water, or a composition containing water comprising in the order of 1 to 200 mg of transition metal per liter of composition, wherein the water-containing composition is an emulsion or suspension.

7. The method according to claim 1, wherein the transition metal is in a composition containing water, or a composition containing water comprising in the order of 1 to 200 mg of transition metal per liter of composition, wherein the water-containing composition is an oil-in-water or water-in-oil emulsion.

8. The method according to claim 1, wherein the transition metal is in a composition containing water, or a composition containing water comprising in the order of 1 to 200 mg of transition metal per liter of composition, wherein the water-containing composition is an oil-in-water or water-in-oil emulsion, said transition metal being copper, silver or gold in the form of nanoparticles.

9. A composition containing a transition metal in insoluble form, wherein the transition metal in insoluble form is in the form of a transition metal with oxidation state 0 or in the form of a sulfide or a transition metal oxide, wherein the transition metal is selected from the group consisting of copper, silver and gold, wherein said transition metal in insoluble form is put into aqueous solution by the formation of nanoparticles by adding surfactant, and wherein said transition metal is contained in a structure consisting of a core containing said transition metal, surrounded by a surfactant shell.

10. The composition according to claim 9, wherein the surfactant is selected from an RX, X being a derived radical of a mineral or organic acid, or NO.sub.3.sup.−, SO.sub.4.sup.−, CH.sub.3COO.sup.−, or X being a halogen or other acidic radical, R being a C1-C20 alkyl trimethylammonium, or wherein said surfactant is cetyltrimethylammonium or octyltrimethylammonium, a polyethylene glycol, or polyethylene glycol-dithiol.

11. The composition according to claim 9, said composition being a pharmaceutical composition or a veterinary composition, said pharmaceutical composition or veterinary composition optionally comprising as excipients at least one vegetable oil, or argan oil, grape seed, avocado, hemp or apricot kernels, or a cosmetic composition.

12. The composition according to claim 9, said composition being a pharmaceutical composition or a veterinary composition, wherein said transition metal is at a dose of 1 mg to 1 g of transition metal per liter of composition, or said composition being a cosmetic composition comprising in the order of 1 to 200 mg of transition metal per liter of composition.

13. The composition according to claim 9, said composition being a pharmaceutical composition or a veterinary composition, the form of administration of which is topical.

14. Method of cosmetic treatments comprising administrating a transition metal in insoluble form to a person in need thereof, wherein the transition metal in insoluble form is in the form of a transition metal with oxidation state 0 or in the form of a sulfide or a transition metal oxide, wherein the transition metal is selected from the group consisting of copper, silver and gold, wherein said transition metal in insoluble form is put into aqueous solution by the formation of nanoparticles by adding surfactant, and wherein said transition metal is contained in a structure consisting of a core containing said transition metal, surrounded by a surfactant shell.

Description

FIGURES:

(1) FIG. 1 shows an HR-TEM image of the SAg.sub.2 particles according to Example 4.

(2) FIG. 2 shows the UV-visible absorption spectrum of an aqueous suspension of silver nanoparticles at a concentration of 0.2 wt % silver according to Example 8B.

(3) FIG. 3 shows HR-TEM images of the silver particles of Example 8B. A, B, C and D correspond to different size scales.

(4) FIG. 4 shows the UV-visible absorption spectrum of the silver nanoparticle solution at a concentration of 0.14 g.l.sup.−1 (Example 8C) compared to the solution of Example 8B.

(5) FIG. 5 shows an HR-TEM microscopy image made on the 0.14 g.l.sup.−1 suspension of Example 8C. A, B, C and D correspond to different size scales.

(6) FIG. 6 shows HR-TEM images of the 2 g.l.sup.−1 solution prepared in Example 8C. A and B correspond to different size scales.

(7) FIG. 7 shows an HR-TEM image of the colloidal solution of silver nanoparticles at 2 g.l.sup.−1 obtained after vacuum distillation of a portion of the water of a suspension at 0.2 g.l.sup.−1, according to Example 8D.

(8) FIG. 8 shows a histogram of the size distribution of the silver nanoparticles in a concentrated suspension at 2 g.l.sup.−1 according to Example 8D. The counting of nanoparticles and the determination of the size of each of them are made on a microscope slide.

(9) FIG. 9 shows an HR-TEM image of silver nanoparticles obtained according to method 8. B but in the presence of octyltrimethylammonium bromide (OTAB) according to Example 8E.

(10) FIG. 10 shows a histogram of the size distribution of the silver nanoparticles in a concentrated suspension at 0.2 g.l.sup.−1 prepared in the presence of octyltrimethylammonium bromide (OTAB) according to Example 8E. The counting of nanoparticles and the determination of the size of each of them are made on a microscope slide.

(11) FIG. 11 shows an HR-TEM image of the gold nanoparticle suspension according to Example 9.

(12) FIG. 12 shows an HR-TEM image of the colloidal solution comprising the copper nanoparticles according to Example 10.

(13) FIG. 13 shows an HR-TEM image of the colloidal solution comprising the copper nanoparticles according to Example 10.

(14) FIG. 14 represents an HR-TEM image of the colloidal solution comprising the sulfur nanoparticles according to Example 11.

EXAMPLES

I) Synthesis of the Complexes

Example 1 SCu Solution

(15) Dissolve 126 mg of SO.sub.4Cu in 90 mL of water.

(16) Dissolve 140 mg of Na.sub.2S in 20 mL of water.

(17) Mix the 90 mL of the SO.sub.4Cu solution with 10 mL of the Na.sub.2S solution. A precipitate of 75 mg of SCu is obtained. Separate it by filtration.

(18) Place this precipitate in 100 mL of water in a stirred container.

(19) With constant stirring, drop a very concentrated solution of NH.sub.3 into the water very slowly.

(20) The maximum concentration of SCu in water is 0.33 mg.l.sup.−1 SCu becomes more soluble in aqueous solution in the presence of ammonia. The addition of ammonia to copper sulfide makes it possible to reach an aqueous concentration of at least 0.2 g.l.sup.−1 in Cu.

Example 2 SAg.SUB.2 .Solution

(21) Dissolve 79 mg of NO.sub.3Ag in 97 mL of water.

(22) Mix the 97 mL of the NO.sub.3Ag solution with 3 mL of the Na.sub.2S solution. A precipitate of 75 mg of SAg.sub.2 is obtained. Separate it by filtration.

(23) Place this precipitate in 100 mL of water in a stirred container.

(24) With constant stirring, drop very slowly a concentrated solution of ammonium citrate (NH.sub.4).sub.5(C.sub.6H.sub.4O.sub.7).sub.2H.sub.3.

(25) The maximum concentration of SAg.sub.2 in water is 6.21.10.sup.−15 g.l.sup.−1. SAg.sub.2 becomes more soluble in the presence of citric acid, or a mixture of ammonium citrate and citric acid, or a mixture of ammonium citrate and ammonia, the ammonium citrate being formed by a mixture of citric acid and ammonia. The addition of citric acid, or a mixture of ammonium citrate and citric acid, or a mixture of ammonium citrate and ammonia, to the silver sulfide makes it possible to reach a concentration at least 0.2 g.l.sup.−1 in Ag.

Example 3 Solution S.SUB.3.Au.SUB.2

(26) Dissolve 77 mg of Cl.sub.3Au in 95 mL of water. Mix the 95 mL of the Cl.sub.3Au solution with 5 mL of the Na.sub.2S solution. A precipitate of 62 mg of S.sub.3Au.sub.2 is obtained. Separate it by filtration.

(27) Place this precipitate in 100 mL of water in a stirred container.

(28) While stirring constantly, drop a very concentrated solution of potassium dichromate very slowly. The maximum concentration of Au.sub.2S.sub.3 in water is undetectable. The aqueous solubility of Au.sub.2S.sub.3 is increased in the presence of potassium dichromate, or a mixture of potassium dichromate and ammonia. The addition of potassium dichromate, or a mixture of potassium dichromate and ammonia, to the gold sulfide makes it possible to reach an aqueous concentration of at least 0.2 g.l.sup.−1 in Au.

II) Synthesis of Metal Sulfide Nanoparticles

Example 4 SAg.SUB.2 .Nanoparticles

Example 4A. SAg.SUB.2 .Nanoparticles

(29) All reagents are used as received, without prior purification.

(30) The water used to prepare the solution is ultra-pure water degassed and stored under Argon.

(31) The reaction takes place under Argon at room temperature (20° C.).

(32) The silver solution is handled in the dark (protection under aluminum). For the synthesis of 200 mL of 0.2 wt % colloidal solution (2 g.l.sup.−1) of silver nanoparticles:

(33) For the preparation of solution A, prepare 80 ml of ultrapure water in a flask and dissolve first 1.35 g of cetyltrimethylammonium bromide (CTAB, 3.7.10.sup.−3 mol) in water and then 0.4 g Ag.sup.+ in the form of AgNO.sub.3 (2.3.10.sup.−3 mol) and adjust to 100 ml with ultrapure water. Store cold, in the dark.

(34) For the preparation of solution B, prepare 50 mL of ultra-pure water in a flask, dissolve 0.144 g of Na.sub.2S (1.85×10 −3 mol) and adjust to 100 mL with ultrapure water.

(35) At room temperature, in the dark, under an argon atmosphere and with stirring (600 rpm), add dropwise solution A to solution B. Allow to react for 4 hours. The SAg.sub.2 particles are characterized by HR-TEM, FIG. They have a wide size distribution with a majority presence of particles larger than 20 nm. Example 4B. SAg.sub.2 nanoparticles, effect of temperature

(36) Silver sulfide nanoparticles are synthesized according to Example 4A at 0° C.

(37) There is an insignificant difference in bactericidal activity between nanoparticles obtained at room temperature and those obtained at 0° C. (see table 1 lines R and 0)

Example 4C. SAg.SUB.2 .Nanoparticles, Effect of Surfactant

(38) Silver sulfide nanoparticles are synthesized according to Example 4A, using PEG-600 in place of CTAB.

Example 5 SCu Nanoparticles

Example 5A. SCu Nanoparticles

(39) All reagents are used as received, without prior purification.

(40) The water used to prepare the solution is ultra-pure water degassed and stored under Argon.

(41) The reaction takes place under Argon at room temperature (20° C.). For the synthesis of 200 mL of 0.2 wt % colloidal solution (2 g.l.sup.−1) of copper nanoparticles:

(42) For the preparation of solution A, prepare 80 ml of ultra-pure water in a flask and first dissolve 1.35 g of CTAB (3.7.10.sup.−3 mol) in water and then 0.4 g of Cu2+ in the form of CuSO.sub.4 (2.5.10.sup.−3 mol) and adjust to 100 mL with ultrapure water. Store cold, in the dark.

(43) To prepare solution B, prepare 50 mL of ultra-pure water in a flask, dissolve 0.5 g of Na.sub.2S (0.64.10.sup.−3 mol) and adjust to 100 mL with ultra-pure water. pure.

(44) At room temperature, in the dark, under an argon atmosphere and with stirring (600 rpm), add dropwise solution A to solution B. Allow to react for 4 hours.

Example 5B. SCu Nanoparticle, Effect of Temperature

(45) Copper sulfide nanoparticles are synthesized according to Example 5A at 0° C. There is no difference in the bactericidal activity between the nanoparticles obtained at ambient temperature and those obtained at 0° C. (see lines Q and T of Table 1)

Example 5C. Nanoparticle SCu, Effect of Surfactant

(46) Copper sulfide nanoparticles are synthesized according to Example 5A, using PEG-600 in place of CTAB.

Example 6 S.SUB.3.Au.SUB.2 .Nanoparticles

Example 6A. S.SUB.3.Au.SUB.2 .Nanoparticles

(47) All reagents are used as received, without prior purification.

(48) The water used to prepare the solution is ultra-pure water degassed and stored under Argon.

(49) The reaction takes place under Argon at room temperature (20° C.).

(50) The gold solution is handled in the dark (protection under aluminum). For the synthesis of 200 mL of 0.2 wt % colloidal solution (2 g.l.sup.−1) of gold nanoparticles:

(51) For the preparation of solution A, prepare 80 mL of ultrapure water in a flask and first dissolve 1.35 g of CTAB (3.7.10.sup.−3 mol) in water and then 0.4 g of Au.sup.3+ in the form of AuCl.sub.3 (1,3.10.sup.−3 mol) and adjust to 100 mL with ultrapure water. Store cold, in the dark.

(52) For the preparation of solution B, prepare 50 mL of ultra-pure water in a flask, dissolve 0.234 g of Na.sub.2S (0.3.10.sup.−3 mol) and adjust to 100 mL with ultrapure water.

(53) At room temperature, in the dark, under an argon atmosphere and with stirring (600 rpm), add dropwise solution A to solution B. Allow to react for 4 hours.

Example 6B. S.SUB.3.Au.SUB.2 .Nanoparticles, Effect of Temperature

(54) Gold sulfide nanoparticles are synthesized according to Example 6A at 0° C.

(55) The nanoparticles obtained at room temperature are a little more efficient than those obtained at 0° C. (see Table 1 lines P and S)

III) Synthesis of Transition Metal Nanoparticles

Example 7 How to Synthesize Suspensions of Metallic Nanoparticles in Water?

(56) The metallic nanoparticles in water are generated by the reaction of a salt of the metal and a reagent:

(57) the reagent being an oxidant to obtain nanoparticles of metal oxides;

(58) the reagent being a reducing agent to obtain metal nanoparticles.

(59) In addition, the metal salts must be stabilized in “cages” in order to prevent agglomeration of nanoparticles into larger and more stable particles.

(60) The cages are generally formed with surfactants having a hydrophilic portion and a hydrophobic portion. These cages, in an aqueous medium, are called micelles.

Example 8. Silver Nanoparticles, Ag

Example 8. A Selection of Reagents

(61) The available silver salt (and the most common) is AgNO.sub.3. (Aldrich, 99%, M=169.9 g.mol.sup.−1, assay 63.4% Ag).

(62) The surfactant used is CTAB (cetyltrimethylammonium bromide).

(63) The reducer chosen is glycerol.

(64) The use of glycerol involves the use of a base to enhance its reducing properties. NaOH was used for this purpose to produce a basic solution of glycerol in water. These solutions aim to reduce the Ag.sup.+ metal salt by converting glycerol to dihydroxyacetone (DHA).

Example 8.B Synthesis of 200 mL of 0.2 wt % Colloidal Solution (2 g.l.SUP.−1.) of Silver Nanoparticles

(65) All reagents are used as received, without prior purification. The water used to prepare the solution is ultra-pure water degassed and stored under Argon. The reaction takes place under Argon at room temperature (20° C.). The silver solution is handled in the dark (protection under aluminum). For the preparation of solution A, prepare 80 ml of ultrapure water in a flask and first dissolve 1.35 g of CTAB (3.7×10.sup.−3 mol) in water and then 0.4 g Ag.sup.+ ion as AgNO.sub.3 (2.3.10.sup.−3 mol) and adjust to 100 mL with ultrapure water. Store cold, in the dark.

(66) For the preparation of solution B, prepare 50 mL of ultra-pure water in a flask, dissolve 34 g of glycerol (0.37 mol) and then 8 g of NaOH (0.2 mol) and adjust to 100 mL with ultra-pure water.

(67) At room temperature, in the dark, under an argon atmosphere and with stirring (600 rpm), add dropwise solution A to solution B. Allow to react for 4 hours. At the end of the reaction, adjust the pH to 7 by adding concentrated commercial HCl (24 M). The corresponding volume to be added is from 0.8 to 0.9 ml.

(68) The resulting solution is analyzed by UV-visible spectroscopy and the morphology and size of the particles obtained are analyzed by high-resolution transmission electron microscopy (HR-TEM).

(69) The UV-visible absorption wavelength is specific to the size and quantity of the nanoparticles in suspension. The UV-visible spectroscopic analysis of the colloidal suspension of silver nanoparticles at a concentration of 0.2 wt % is shown in FIG. The solution has no deposit, all the money initially introduced is in colloidal form.

(70) The distribution is mono-modal with a wavelength centered at 410 nm, indicating a nanoparticle size of less than 40 nm. The size of the nanoparticles is then confirmed by HR-TEM microscopy.

(71) The images obtained by HR-TEM are presented in FIG. 3, at different scales. The nanoparticles are homogeneous in size, with an average diameter of 15 nm.

Example 8.0 Effect of Reagent Concentration on Nanoparticle Formation

(72) In order to increase the concentration of nanoparticles and reach a concentration of 2 g.l.sup.−1 (0.2 wt %) in silver, the amount of reagents was increased. However, the total amount of CTAB is not soluble under these conditions and most of it precipitates. The stabilization of silver nanoparticles is no longer assured.

(73) The UV-visible absorption spectrum resulting from a suspension that has been diluted about 50-fold to avoid saturation of the UV spectrum is shown in FIG. 4. It can be deduced from the comparison of this spectrum with the spectrum obtained in Example 8.B that the solution has a silver concentration of 0.14 g.l.sup.−1.

(74) An HR-TEM microscopy analysis was performed on this suspension diluted to 0.14 g.l.sup.−1. The distribution is bimodal with nanoparticles having a diameter of about 30 nm and smaller nanoparticles with a diameter of less than 5 nm. This behavior is directly related to a stabilizer defect.

(75) The solution obtained according to the method 8. B but with a concentration of 2 g.l.sup.−1 in silver, is golden in color. The HR-TEM images of this solution 2 g.l.sup.−1 (concentrated solution prepared in 8.0 are reported in FIG. 6. The particles obtained are not homogeneous. FIG. 6A illustrates the presence of nanoparticles with an average diameter of 30 nm, these nanoparticles being of various shapes (rods, spheres). Small spherical nanoparticles, whose average diameter is 5 to 10 nm, are also present in the solution, as shown in FIG. 6B.

Example 8.D Effect of the Concentration eh Silver on the Size of the Silver Nanoparticles

(76) The silver concentration is obtained by vacuum distillation of water (p=15 mbar at 20° C.) of the initial colloidal solution prepared according to Example 8.B.

(77) A solution of silver nanoparticles with a concentration of 0.2 g l.sup.−1 and smaller than 15 nm (Example 8.B) is concentrated by vacuum distillation of water to give a silver concentration of 2 g.l.sup.−1. The resulting solution is cloudy and golden.

(78) The images obtained by HR-TEM of this new suspension are shown in FIG. 7.

(79) The generally spherical nanoparticles have a broad size distribution (5 to 20 nm), FIGS. 7 and 8.

(80) It should be noted, however, that CTAB precipitates upon removal of water.

Example 8.E Effect of the Nature of the Surfactant on the Formation of Nanoparticles

(81) A nanoparticle solution is produced according to Example 8.B using octyltrimethylammonium bromide (OTAB) in place of cetyltrimethylammonium bromide (CTAB).

(82) The resulting solution is green. A hypsochromic displacement of the wavelength of the absorption maximum of this solution is indeed observed during the analysis by UV-visible absorption spectroscopy. Plasmon generated on the surface is therefore more energetic than when the nanoparticles are formed in the presence of CTAB.

(83) FIG. 9 represents an image obtained by HR-TEM microscopy of the green solution. The size of the nanoparticles is very small, with a diameter of less than 5 nm. An average diameter of 3.7 nm is determined by an analysis of the particle size distribution of the solution (FIG. 10).

(84) The counting of nanoparticles and the determination of the size of each of them are made on a microscope slide. 100 nanoparticles are needed so that the determined size distribution is representative of the entire population of the starting colloidal solution. Then the distribution is adjusted by a log-normal law.

Example 8F. Effect of the Nature of the Surfactant on the Formation of Nanoparticles

(85) A nanoparticle solution is produced according to Example 8.B using PEG-dithiol in place of cetyltrimethylammonium bromide (CTAB).

Example 9. Gold Nanoparticles, Au

(86) All reagents are used as received, without prior purification. The water used to prepare the solution is ultra-pure water degassed and stored under Argon. The reaction takes place under Argon at room temperature (20° C.).

(87) 200 mL of 0.2 wt % colloidal solution (2 g./l) in gold nanoparticles are synthesized by following the following steps:

(88) For the preparation of solution A, prepare 80 mL of ultra-pure water in a flask and first dissolve 0.73 g of CTAB (2.0.10.sup.−3 mol) in water and then 0.4 g Au.sup.3+ in the form of AuCl.sub.3 (1,3.10.sup.−3 mol) and adjust to 100mL with ultrapure water. Store cold.

(89) For the preparation of solution B, prepare 50 mL of ultra-pure water in a flask, dissolve 0.2 mol of glycerol (18.4 g) then 0.2 mol of NaOH (8 g) and adjust to 100 mL with ultra-pure water. At room temperature, under an argon atmosphere and with stirring (600 rpm), add dropwise solution A to solution B. Allow to react for 4 hours.

(90) At the end of the reaction, adjust the pH to 7 by adding concentrated commercial HCl (24 M). The corresponding volume to be added is from 0.8 to 0.9 mL

(91) FIG. 11 represents an HR-TEM image of the obtained gold nanoparticles. Their sizes vary between 10 and 30 nm.

Example 10 Copper Nanoparticles, Cu

Example 10A. Synthesis of Copper Nanoparticles, Cu Copper Nanoparticles Are Synthesized According to the Protocol Described in Example 8B:

(92) All reagents are used as received, without prior purification. The water used to prepare the solution is ultra-pure water degassed and stored under Argon. The reaction takes place under Argon at room temperature (20° C.).

(93) For the preparation of solution A, prepare 80 mL of ultrapure water in a flask and first dissolve 1.35 g of CTAB (3.7.10.sup.−3 mol) in water and then 0.4 g of Cu.sup.2+ in the form of Cu(NO.sub.3).sub.2 (Molar mass: 187.56 g/mol: 0.75 g Cu(NO.sub.3).sub.2=4.10.sup.−3 mol) and adjust to 100 mL with ultra-pure water. Store cold, in the dark.

(94) To prepare solution B, prepare 50 mL of ultra-pure water in a flask, dissolve 0.37 mol of glycerol (34 g) and then 8 g of NaOH (0.2 mol) and make up to 100 mL with ultra-pure water.

(95) At room temperature, in the dark, under an argon atmosphere and with stirring (600 rpm), add dropwise solution A to solution B. Allow to react for 4 hours.

(96) At the end of the reaction, adjust the pH to 7 by adding concentrated commercial HCl (24 M). The corresponding volume to be added is from 0.8 to 0.9 mL.

(97) FIG. 12 represents an HR-TEM image of the copper nanoparticles included in the colloidal suspension thus obtained.

(98) Clusters of small particles are observed showing that the surfactant does not allow complete stabilization of the copper nanoparticles. Some isolated nanoparticles are also present as illustrated in FIG. 13. These nanoparticles are homogeneous and small, with a diameter of about 2 nm. Example 10B. Effect of the nature of surfactant on the formation of copper nanoparticles

(99) A nanoparticle solution is made according to Example 10A using PEG-600 in place of cetyltrimethylammonium bromide (CTAB).

Example 11 Attempt to Prepare Sulfur Nanoparticles

(100) According to the procedure 8. B from Na.sub.2S and PEG-600 as surfactant: a 0.2 g/l colloidal solution in sulfur was obtained.

(101) Objects homogeneous in size and about 5 nm in diameter but difficult to observe by HR-TEM microscopy due to low contrast (FIG. 14) could be observed. These objects because of their size were called sulfur nanoparticles.

IV) Biological Results

Example 12. MIC Test on MRSA and MSSA Bacteria: Materials and Methods

(102) The bacteria MRSA (Meticillin Resistant Staphylococcus aureus, ATCC 43300) and MSSA (Meticillin Sensitive Staphylococcus aureus, ATCC 29213) were incubated on TSA 24 h at 37° C. The standardization of the bacteria was carried out by producing a farland 0.5 mc with fresh colonies, representing 1.5.10.sup.7 CFU.ml.sup.−1 then the bacterial suspension was diluted 1/100.sup.th in a Mueller Hinton (MH) medium (sigma. 90922-500G) in order to obtain a final bacterial concentration (spf) corresponding to 1.5.10.sup.5 CFU/ml.

(103) Each particle test was performed on a line of a 96-well round bottom plate (ref.353077) in duplicate. 50 μL of MH medium were deposited in the wells. 50 μL of the pure particle were deposited in the first column (column 1) of the plate and successive dilutions of reason 2 were performed by taking 50 μl of each column redeposited in the next column to the last column (column 12). The 50 μl of the last column were discarded. Then 50 μl of the bacterial suspension (spf) was deposited in each well representing a final bacterial concentration per well of 0.75.10.sup.5 CFU.ml.sup.−1. The final concentration of the particle in the first well (column 1) represents a final ¼ dilution with respect to its initial concentration.

(104) Two negative controls were performed with pure MH, and with 50 μL of MH and 50 μL of pure particle to verify that there was no contamination. A positive control was performed with 50 μL of MH and 50 μL of the bacterial suspension (spf).

(105) The plate was incubated for 24 h at 37° C. in a humid chamber. As this method is the reference method for determining the MIC of a particle, a control of the MIC for oxacillin was performed on these same strains MSSA and MRSA.

Example 13 MIC Test on MRSA and MSSA Bacteria: Results

(106) The first bacteria-free cupule is determined to be the Minimum Inhibitory Concentration (MIC) of the particle.

(107) TABLE-US-00001 TABLE 1 Minimal Inhibitory Concentration (MIC) assay of aqueous solutions obtained by use of the present invention on MRSA and MSSA bacteria. The nanoparticles of Ag(O) (according to Example 8), of Cu(O) (according to Example 10) and of Au(O) (according to Example 9) are denoted Ag, Cu and Au, respectively, and the silver sulfide nanoparticles (according to Example 4), copper sulfide (according to Example 5) and gold sulfide (according to Example 6) are respectively denoted Ag.sub.2S, CuS and Au.sub.2S.sub.3. CuSO.sub.4 relates to a solution of soluble copper salt in the meaning of the invention, that is to say a solution of copper sulfate in water. S represents an aqueous solution of sulfur nanoparticles prepared according to Example 11. MICMSSA MIC MRSA Number Particle/quantity (g/l) (g/l) Control Oxacilline  2.5 .Math. 10.sup.−4  0.256 A Ag (Example 8B) 7.81 .Math. 10.sup.−4 7.81 .Math. 10.sup.−4 B Ag (Example 8F) 0.05  0.05 D S   (Example 11) 0.05  0.05 F Cu 0.2 g/L (Example 10A) 4.88 .Math. 10.sup.−5 9.71 .Math. 10.sup.−5 H Au (Example 9) 4.88 .Math. 10.sup.−5  3.9 .Math. 10.sup.−4 K Cu (Example 10B) 0.025 0.05 L Ag.sub.2S PEG-600  0.0125 Not done (Example 4C) N CuS PEG-600 (Example 5C)  0.0125 Not done O Ag.sub.2S (Example 4A) 1.95 .Math. 10.sup.−4  3.9 .Math. 10.sup.−4 P Au.sub.2S.sub.3 (Example 6A) 2.44 .Math. 10.sup.−5 4.88 .Math. 10.sup.−5 Q CuS (Example 5A) 9.71 .Math. 10.sup.−5 9.71 .Math. 10.sup.−5 R Ag.sub.2S (Example 4B) 1.95 .Math. 10.sup.−4 1.95 .Math. 10.sup.−4 S Au.sub.2S.sub.3 (Example 6B) 4.88 .Math. 10.sup.−5 9.71 .Math. 10.sup.−5 T CuS (Example 5B) 9.71 .Math. 10.sup.−5 9.71 .Math. 10.sup.−5 V CuSO.sub.4 0.078 0.078-0.157 A + D ⅛ D + ⅞ A 7.81 .Math. 10.sup.−4 7.81 .Math. 10.sup.−4 H + D ⅛ D + ⅞ H 9.71 .Math. 10.sup.−5 9.71 .Math. 10.sup.−5 F + D ⅛ D + ⅞ F 4.88 .Math. 10.sup.−5 1.95 .Math. 10.sup.−4 D + A + H ⅛ D + 3, ⅝ A + 3, ⅝ H 9.71 .Math. 10.sup.−5 1.95 .Math. 10.sup.−4 D + A + F ⅛ D + 3, ⅝ A + 3, ⅝ F 9.71 .Math. 10.sup.−5 9.71 .Math. 10.sup.−5 D + H + F ⅛ D + 3, ⅝ H + 3, ⅝ F 4.88 .Math. 10.sup.−5 9.71 .Math. 10.sup.−5 D + A + ⅛ D + 2/8 A + 2/8 H + ⅜ F 4.88 .Math. 10.sup.−5 9.71 .Math. 10.sup.−5 H + F D + K ⅛ D + ⅞ K 0.025 0.05 O + P ½ O + ½ P 9.71 .Math. 10.sup.−5 9.71 .Math. 10.sup.−5 P + Q ½ P + ½ Q 4.88 .Math. 10.sup.−5 9.71 .Math. 10.sup.−5 O + Q 1/2 O + ½ Q 7.81 .Math. 10.sup.−4 1.95 .Math. 10.sup.−4

(108) The control represents the expected MIC for these strains. The MICs of the different particles show a bactericidal effect for most of the MSSA and MRSA strains at different concentrations.

(109) In addition, the nanoparticles of the invention are all better inhibitors of MRSA than oxacillin. Oxacillin, used herein as a reference, is an example of an active substance used in case of infection with Staphylococci. Among the compounds of the invention, the copper nanoparticles, the gold sulfide nanoparticles and the copper sulfide nanoparticles have the best inhibition rates, both of the MSSA bacteria and of the MRSA bacteria.

Example 14. MIC Test on Gram-positive/Negative Bacteria and Yeasts

(110) The nanoparticle in question is copper sulfide surfactant with CTAB, synthesized according to Example 5, the copper source being copper nitrate, Cu(NO.sub.3).sub.2, and not copper sulphate. The tests are carried out according to the method described in Example 12

(111) The activities are measured by the MIC (Minimum Inhibitory Concentration), the index generally used, expressed here in mg per liter. One mg per liter represents a ppm:

(112) TABLE-US-00002 Gram-positive bacteria Staphylococcus Aureus 0.&5 Propionibacterium Acnes 0.07 Gram-negative bacteria Pseudomonas Aeruginosa 1.2 Yeast Candida Albicans 0.32

(113) These nanoparticles are active in particular on the bacterium that produces acne: the minimum inhibitory concentration against Propionibacterium acnes is 0.07 mg per liter.

(114) Copper sulfide nanoparticles are not only active, but are also very well tolerated, in particular since the concentration in an anti-acne cream is low: in the order of ppm.

Example 15

(115) It should be noted that in all of the above examples involving CTAB, it can be reduced to a molar concentration equal to 0.5 times that of the metal.

(116) Two suspensions of copper sulfide nanoparticles with a CTAB/Cu ratio of 1 and 0.2 respectively were prepared according to the protocol of Example 5 and using the starting materials below.

(117) TABLE-US-00003 CuSO.sub.4•5H.sub.2O Molar mass: 249.69 g Na.sub.2S•9H.sub.2O Molar mass: 240.18 g CTAB Molar mass: 364.45 g

(118) Solution at 2 g/l Cu (Molar mass: 63.55 g)

(119) 0.2 g per 100 ml corresponding to 3.15 mmol of CuSO.sub.4.5H.sub.2O

(120) Two suspensions of CuS in 100 ml of water were prepared at room temperature.

(121) Suspension 1 CTAB/Cu ratio=1 in 100 ml

(122) 3.15 mmol CuSO.sub.4.5H.sub.2O that is m=0.786 g

(123) 3.15 mmol Na.sub.2S.9H.sub.2O that is m=0.757 g

(124) 3.15 mmol of CTAB that is m=1.148 g

(125) These suspensions are stable after 48 hours at room temperature

(126) Suspension 2 CTAB/Cu ratio=0.5

(127) 3.15 mmol CuSO.sub.4.5H.sub.2O that is m=0.786 g

(128) 3.15 mmol Na.sub.2S.9H.sub.2O that is m=0.757 g

(129) 0.64 mmol of CTAB that is m=0.230 g

(130) These suspensions are stable after 48 hours at room temperature

Example 16

(131) The tests on CuS at 1 of CTAB (suspension 2 of Example 15) were made by Ideatest Group.

(132) The bacterium tested is Propionibacterium acnes, responsible for acne.

(133) The results are as follows

(134) The lethal concentration is 1 mg/l (one part per million)

(135) There are two other measures, also determined by Ideatest Group. The current measure in Europe is the 4 log concentration (which divides the bacterial population by 10 000) in five minutes. This is achieved for Propionibacterium acnes with 1 mg/l.

(136) The standard AFNOR EN 1276, for medical use, much more rigid, is 5 log in five minutes (It divides the bacterial population by 100 000). This is achieved for Propionibacterium acnes with 2 mg/l.

(137) A tolerance check was also done by Ideatest Group. Europe now prohibits animal testing and men in this area, laboratories have developed a new method. It involves culturing human skin cells, assembling them in layers to form a “reconstructed skin” and testing on this reconstructed skin.

(138) These tests were made with a concentration of 20 mg/l to have a very wide margin of safety. Unlike all anti-acne agents currently on the market, the nanoparticle of the invention produces no irritation.

(139) Other tests were made with CuS at 10 CTAB, (Example 5) in inhibitory concentration: they gave the following results, in mg.l.sup.−1. 1 mg.l.sup.−1corresponds to one ppm, part per million:

(140) TABLE-US-00004 Gram-positive bacteria Staphylococcus Aureus 0.15 Propionibacterium Acnes 0.07 Gram-negative bacteria Escherichia coli 1.2 Pseudomonas Aeruginosa Yeasts Candida Albicans 0.32

(141) These results cover all the families of germs, gram-positive, gram-negative and fungi in particular yeasts. They are excellent.

Example 17 Composition

(142) Anti-acne cream, 80% water 20% oil, containing 2 ppm SCu prepared with CTAB as surfactant, the molar concentration ratio of CTAB/Cu was 0.2, made at room temperature.

Example 18 Tests of CuS at 1.15 of CTAB with Respect to Staphylococcus aureus

(143) The measurements on CuS at 1, 15 of CTAB were carried out by the CIRI:

(144) Hospices Civils de Lyon—International Center for Research in Infectiology (CIRI)

(145) Croix-Rousse Hospital

(146) Center of Northern Biology—Laboratory of Bacteriology—Bat O.

(147) 103 Great Rue de la Croix Rousse, 69004 LYON, France

(148) The bacterium tested is Staphylococus aureus.

(149) The results are as follows:

(150) The CIRI sought the MIC, Minimal Inhibitory Concentration

(151) On the one hand on MRSA, Meticillin Resistant Staphylococcus aureus

(152) On the other hand on the MSSA, Meticillin Sensitive Staphylococcus aureus

(153) In both cases the MIC was the same: 0.1 mg/l

Example 19 Tests of CuS at 1.15 of CTAB with Respect to the Propionibacterium acnes Bacteria

(154) The CuS tests at 1.15 of CTAB were performed by the Ideatest Group (Idea Lab, Montesquieu Technopole 5, rue Jacques Monod CS 60077 33652 MARTILLAC CEDEX).

(155) The bacterium tested is Propionibacterium acnes, responsible for acne.

(156) The results are as follows:

(157) The product was tested at concentrations: 0.07, 0.25, 0.5, 1 and 2 mg/l. The monitoring was carried out on the 5 minutes, 24 h and 6 days.

(158) The microorganism tested was removed from freezing (−80° C.) and was twice plated on appropriate medium (TSA: Tryptic Soy Agar). This medium was incubated at 36° C. (±2.5° C.) for 6 days in anaerobic jar in the presence of anaerocult (Merck), P. acnes requiring anaerobic conditions for growth.

(159) The suspension to be tested was prepared extemporaneously in sterile physiological water from the culture on agar medium. The density thus obtained was adjusted by measuring the OD at 620 nm; it should be around 10.sup.8 cells/ml.

(160) The microorganism to be tested was placed extemporaneously in a liquid medium with a double concentration favorable for its growth (TSB: Tryptic Soy Broth), then immediately inoculated into the product at a final density of between 10.sup.5 and 10.sup.6 Forming Unit colonies/ml. More specifically, the contact between the microbial preparation and the test product was made by volume-to-volume addition in a sterile glass vial.

(161) After the 5 min sampling, the anaerobic incubations of the P. acnes preparations were conducted in a thermostatically controlled chamber for 24 hours and 6 days.

(162) At the end of the incubation periods, counts were made in TSA medium, after dilution-neutralization to LT100 over appropriate dilution ranges. The anaerobic incubations of the seeded boxes were then conducted in thermostatically controlled enclosures for 6 days.

(163) The bactericidal activity of the products is evaluated by comparing the densities obtained at the final time (Tf) with those noted at the initial time (TO). The bactericidal potential is estimated from the reduction obtained. It must be greater than 4 log for bacteria.

(164) The bacteriostatic activity of the products is appreciated by the possible decrease in the growth of microbial germs between control (Tef) and test product (Tf).

(165) The following table presents the densities obtained at: Initial time (TO), the densities being the same for the control and the tests and being in this case 5.0.10.sup.5 CFU/ml. Follow-up time for the control (control) and the tests (0.07, 0.25, 0.5, 1 and 2 mg/l).

(166) The results are expressed in CFU/ml.

(167) TABLE-US-00005 Control 0.07 0.25 0.5 1 2 T 5 min 5.0.105 9.3.104 1.0.105 1.2.105 1.0.102 <10 T 24 h 7.0.105 3.9.105 3.7.105 7.4.104 <10 <10 T 6 d 3.3.106 6.9.105 9.0.105 1.8.104 <10 <10

(168) The log deductions obtained at each of the times are then calculated with reference to the density TO:

(169) TABLE-US-00006 Control 0.07 0.25 0.5 1 2 T 5 min 0.0 0.7 0.7 0.6 3.7 4.7 T 24 h −0.1 0.1 0.1 0.8 4.7 4.7 T 6 jd −0.8 −0.1 −0.3 1.4 4.7 4.7

(170) On the basis of the study carried out, the test product exhibited a bactericidal activity at a concentration of 1 mg/l.

Example 20 Tests of CuS at 1.15 of CTAB with Respect to the Bacterium Acinetobacter baumannii

(171) The CuS tests at 1.15 of CTAB were performed by the Microbiological Safety Unit of the Pasteur Institute of Lille (1 rue du Professeur Calmette PO Box 245-59019 LILLE Cedex).

(172) The bacterium tested is Acinetobacter baumannii resistant to penicillins, cephalosporins, carbapenems, quinolones, aminoglycosides (gentamycin).

(173) The results are as follows:

(174) A series of successive dilutions to ½ of the product was carried out. Each dilution was brought into contact with the bacterial suspension of Acinetobacter baumannii (BAA 1792 strain resistant to Penicillins, cephalosporins, carbapenems, quinolones, Aminoglycosides (gentamycin)) and incubated at 37° C. After 24 hours, the tubes with a disorder indicate bacterial growth; the lowest concentration of product for which no disorder is observed is the minimum inhibitory concentration (MIC).

(175) The contents of each tube with no disturbance was then deposited on nutrient agar and incubated at 37° C. After 24 hours, the agars on which no colony is observed indicate that the tube no longer contained culturable bacterium. The lowest concentration of product for which no colony is observed is the minimum bactericidal concentration (MBC).

(176) The MIC of the product with respect to Acinetobacter baumannii has been estimated at 4.8 mg/l for concentrations equal to or greater than this value, bacterial multiplication is inhibited (bacteriostatic effect).

(177) The MBC was estimated at 19.2 mg/l for product concentrations greater than or equal to this value, no residual bacterial population appears on agar (bactericidal effect). The CMB was therefore selected as the value to be tested in standard NF EN 1276, as well as a higher concentration (30 mg/l) and a lower estimated non-bactericidal concentration (0.3 mg/l).

Example 21 Tests of CuS at 1.15 of CTAB with Respect to Yeast Candida albicans

(178) The CuS tests at 1.15 of CTAB were performed by the Microbiological Safety Unit of the Pasteur Institute of Lille (1 rue du Professeur Calmette PO Box 245-59019 LILLE Cedex).

(179) Yeast tested is Voriconazole-resistant Candida albicans, Itraconazole, Fluconazole, Anidulafungin

(180) The results are as follows:

(181) The procedure used for the determination of the MICs and CMLs is identical to that described in Example 19.

(182) The MIC of the product against Candida albicans has been estimated at 4.8 mg/l for concentrations equal to or greater than this value, microbial growth is inhibited (growth inhibitory effect).

(183) CML was estimated at 9.6 mg/l for product concentrations greater than or equal to this value, no residual microbial population appears on agar (microbicidal effect).

(184) The CML was therefore selected as the value to be tested in the NF EN 1650 standard, as well as a higher concentration (20 mg/l) and a lower estimated non-microbicidal concentration (0.3 mg/l).

Example 22 Tests of CuS at 1.15 of CTAB with Respect to the Bacterium Escherichia coli

(185) The CuS tests at 1.15 of CTAB were performed by the Microbiological Safety Unit of the Pasteur Institute of Lille (1 rue du Professor Calmette BP 245-59019 LILLE Cedex).

(186) The bacterium tested is Escherichia coli producing extended-spectrum beta-lactamase (ESBL), carbapenem-resistant

(187) The results are as follows:

(188) The procedure used for the determination of the MICs and CMLs is identical to that described in Example 19. The MIC of the product with respect to Escherichia coli was estimated at 9.6 mg/l for concentrations equal to or greater than this value, the bacterial multiplication is inhibited (bacteriostatic effect).

(189) The MBC was estimated at 76.8 mg/l for product concentrations greater than or equal to this value, no residual bacterial population appears on agar (bactericidal effect).

Example 23 Tests for the Safety of CuS at 1.15 of CTAB with Respect to the Skin

(190) The CuS tests at 1.15 of CTAB were performed by the Ideatest Group (Idea Lab, Montesquieu Technopole 5, rue Jacques Monod CS 60077 33652 MARTILLAC CEDEX).

(191) The test consisted of the study of in vitro skin irritation of the reconstructed human epidermis sample (SkinEthic model) according to the OECD guideline 439

(192) The sample was tested at a concentration of 20 mg/m L.

(193) The results are as follows:

(194) The inserts (filter+epidermis) were gently peeled off the agar and if necessary the underside of the inert was wiped on absorbent paper to avoid leaving agar on the polycarbonate filter. The inserts were then placed in wells (6-well culture plate) previously filled with 1 ml of growth medium at room temperature (the absence of bubbles was verified). The cultures were incubated at 37° C., 5% CO.sub.2 overnight.

(195) 16 μL±0.5 μL of sample to be tested were deposited using a positive displacement micropipette on the surface of the tissues and a 7.5 mm diameter nylon disc was gently applied to the surface of the epidermis. using tongs.

(196) The epidermis were incubated in 0.3 mL of maintenance medium (24-well plate) at room temperature for 42 minutes±1 minute.

(197) The nylon discs were removed and the epidermis was rinsed with 25 mL of PBS per epidermis (25 times 1 mL using a dispenser).

(198) The epidermis was incubated in 2 mL of 6-well plate growth medium at 37° C., 5% CO.sub.2 for 42 hours±1 hour (no bubbles were verified). At the end of the incubation period, the plates were stirred for about 2 minutes at 300 rotations per minute to homogenize the mediators or enzymes released into the culture medium.

(199) The culture medium was removed and frozen at −20° C.±5° C. for the optional assay of mediators or enzymes.

(200) All the epidermis were incubated in 0.3 mL of maintenance medium at 1 mg/mL MTT in 24-well plate.

(201) After 3 hours±5 minutes of incubation at 37° C., 5% CO.sub.2, the outside of the inserts was rinsed with 2 ml of PBS. The extraction was carried out by placing the epidermis in wells filled with 0.8 ml of isopropanol and then covered with 0.7 ml of isopropanol for 2 hours±5 minutes with gentle stirring at room temperature. Plates were protected by an adhesive film or parafilm to prevent evaporation. The epidermis was pierced and removed from the wells. The extraction solution was homogenized by successive pipetting and the absorbance was measured in triplicate on 200 μl of 96-well plate extract.

(202) Absorbances were measured at 540 nm against a blank consisting of isopropanol.

(203) The result is expressed as a percentage of viability compared to the negative control.

(204) The irritant potential of the tested element has been determined in accordance with the CLP (European Regulation on the Classification, Labeling and Packaging of Substances and Mixtures) and the United Nations Globally Harmonized System of Classification (GHS) Regulations. and Labeling of Chemicals).

(205) The element tested is considered to be skin irritant (Category 2), if the average relative viability, after 42 minutes of exposure and 42 hours of incubation, is less than or equal to 50% of the negative control.

(206) The tested element is considered non-irritant for the skin (no category), if the average relative viability after 42 minutes of exposure and 42 hours of incubation is 50% of the negative control.

(207) The average viability observed for the sample tested is 88.5%, which is therefore non-irritating.

Example 24 Protocol for Synthesis of Nanoparticles Having a Structure Comprising a Core Containing a Transition Metal, Surrounded by a Surfactant Shell

(208) A solution A is formed of:

(209) 100 this distilled water

(210) 0.4 gr Cu.sub.++, either in the form of SO.sub.4Cu or (NO.sub.3).sub.2Cu. Take care that these two products are delivered in hydrated form with a number of water molecules per variable Cu depending on the suppliers. It must be taken into account so that there is 0.4 gr Cu++

(211) 0,46 CTAB gr

(212) Solution B is formed of

(213) 100 this distilled water

(214) 0.49 gr of Na.sub.2S. Take care that Na.sub.2S can be delivered in a hydrated form with a varying number of Na.sub.2S water molecules depending on the supplier. This must be taken into account so that there is 0.49 gr of Na.sub.2S.

(215) Drop solution B into solution A in one hour, stirring constantly solution A.

(216) The whole synthesis is done at ambient temperature.

Example 25 Replacement of CTAB by Other Surfactants

(217) Principle:

(218) Bromine CTAB is replaced by another acid (e.g. nitric, sulfuric, acetic, amino, . . . ).

(219) Synthesis protocol:

(220) In a CTAB solution pour the stoichiometric amount of silver powder. Silver bromide precipitates. It is removed by filtration. There remains a solution of CTA OH.

(221) The stoichiometric amount of an acid (eg nitric, sulfuric, acetic, amino, etc.) is poured into this solution.

(222) The CTAX formed, where X is the acid used, is then used as the CTAB to produce transition metal nanoparticles, in particular SCu.

Example 26 Comparison of Golden Staphylococcal Activity of Different Metals and

(223) TABLE-US-00007 MIC (Minimal Inhibitory Concentration) in PPB Tested MRSA (Meticillin Resistant MSSA (Meticillin Sensible sample Staphylococcus Aureus) Staphylococcus Aureus) Ag 800 800 SAg, at r.t. 200 50 SAg, 0° C. 200 200 Au 400 50 SAu, at r.t. 50 25 SAu, 0° C. 100 50 Cu 100 50 SCu, at r.t. 100 100 SCu, 0° C. 100 100 At r.t: prepared at room temperature At 0° C.: prepared at 0° C.

Example 27 Comparison of the Activity with Respect to Staphylococcus aureus of Different Metals and Nanoparticles According to the Invention

(224) TABLE-US-00008 MIC (Minimal Inhibitory Concentration ) in PPB Tested MRSA (Meticillin Resistant MSSA (Meticillin Sensible sample Staphylococcus Aureus) Staphylococcus Aureus) A 7.81 × 10.sup.−4 7.81 × 10.sup.−4 B 0.05 0.05 C 1.95 × 10.sup.−4 4.88 × 10.sup.−5 D 0.05 0.05 E no inhibition no inhibition F 9.71 × 10.sup.−5 4.88 × 10.sup.−5 G 9.71 × 10.sup.−5 4.88 × 10.sup.−5 H  3.9 × 10.sup.−4 4.88 × 10.sup.−5 A: Ag 0.2 g/L B: Ag 0.2 g/L PEG dithiol pH = 7 C: Ag.sub.2S/Ag 0.2 g/L/CTAB D: S 0.2 g/L in presence of PEG-60 (S/PEG) E: S 0.2 g/L (S 0.2 g/L/PEG-dithiol) F: Cu 0.2 g/L/CTAB 20% glycerol pH = 7 G: Cu 0.2 g/L/CTAB pH = 7 H: Au 0.2 g/L/CTAB 0.2 g/L