Large-scale controllable preparation method for plasmonic nanonail structure

A large-scale controllable preparation method for synthesizing a gold-silver alloy-type plasmonic nanonail with a gold nanorod as a backbone, wherein the method comprises:

• a. preparing a mixed aqueous solution of a weak reducing agent A and tetrachloroauric acid, and then, adding a strong reducing agent I into the mixed aqueous solution to thoroughly react to obtain a gold decahedral core aqueous solution V;
• b. preparing an aqueous solution of the weak reducing agent A, the tetrachloroauric acid, and a surfactant K, and adding the gold decahedral core solution V into the aqueous solution multiple times to chemically reduce the gold decahedral core solution V, wherein a reduced elemental gold grows for multiple rounds along a longitudinal axis of a gold decahedron to obtain a gold nanorod aqueous solution VI;
• c. thoroughly dissolving silver nitrate and a surfactant C into dimethylformamide (DMF) to obtain a solution III;
• thoroughly washing the gold nanorod aqueous solution VI, adding a amount of surface treatment agent F to obtain a solution VII, and treating an originally smooth surface of the gold nanorod by using the surface treatment agent F to form one or more surface defects after washing;
• thoroughly mixing the gold nanorod with the solutions III and VII, and placing the mixture under a condition of 60-150° C. for reaction, wherein free silver ions are reduced at the defect, and a triangular plate is formed under a adsorption effect of C, that is, a gold-silver alloy-type plasmonic nanonail DMF-water solution is obtained;
• and
• d. adding 0.5%-3% agarose gel into a casting tank of an electrophoresis tank, letting the agarose gel stand at room temperature until the agarose gel is completely solidified, removing a tape, placing the agarose gel and an inner tank into the electrophoresis tank, adding an electrophoresis buffer solution to 1-2 mm above a cassette, adding the gold-silver alloy-type plasmonic nanonail DMF-water solution to a sample tank of the cassette, and energizing the electrophoresis tank for electrophoresis, wherein because a particle size of nanosphere particles is much smaller than that of the nanonail, and a movement speed of the nanospheres is much higher than that of the nanonail, so that by using an electrophoresis method impurities comprising the nanospheres are separated from the nanonail to obtain uniformly dispersed gold-silver alloy-type plasmonic nanonails to further achieve the controllable morphology,
• wherein the nanonail comprises a structure composed of the nanorod and the triangular plate, wherein each end of the nanorod comprises a point and the triangular plate is attached to a side of the nanorod.

A large-scale controllable preparation method for synthesizing a silver-gold-silver alloy-type plasmonic nanonail with a silver-gold-silver alloy nanorod as a backbone, wherein the method comprises:

• a. adding a amount of cationic surfactant cetyltrimethylammonium chloride (CTAC) solution to a gold nanorod aqueous solution VI to make a concentration of CTAC in the gold nanorod aqueous solution range from 0.05-2 mol/L, wherein CTAC with a high concentration is adsorbed on a surface of the gold nanorod, reduces a zeta potential of the gold nanorod, and flocculates, thereby effectively extracting the gold nanorod;
• formulating the extracted gold nanorod to a benzyldimethylhexadecyl ammonium chloride (BDAC) solution with a concentration of 0.01-10 mmol/L, adding silver nitrate and a weak reducing agent A solution separately and simultaneously into the benzyldimethylhexadecyl ammonium chloride (BDAC) solution at a rate of 100-400 μL/h, and thoroughly reacting at a temperature of 40-100° C. for 2-6 h, wherein silver ions are reduced by A and grow along two ends of the gold nanorod to obtain a silver-gold-silver alloy nanorod solution VIII by a chemical reduction method;
• b. thoroughly mixing and stirring silver nitrate and a DMF solution of a surfactant C to obtain a solution III;
• thoroughly washing the silver-gold-silver alloy nanorod aqueous solution VIII at a speed, adding a amount of surface treatment agent F, treating an originally smooth surface of the alloy nanorod by using the surface treatment agent F to form one or more surface defects after washing, and obtaining a solution IX;
• thoroughly mixing the solutions IX and III, and placing the mixture under a condition of 60-150° C. for reaction to obtain a silver-gold-silver alloy-type plasmonic nanonail DMF-water solution;
• and
• c. adding 1.5% agarose gel into a casting tank of an electrophoresis tank, letting the agarose gel stand at room temperature until the agarose gel is completely solidified, removing a tape, placing the agarose gel and an inner tank into the electrophoresis tank, adding an electrophoresis buffer solution to 1-2 mm above a cassette, adding the silver-gold-silver alloy-type plasmonic nanonail DMF-water solution to a sample tank of the cassette, and energizing the electrophoresis tank for electrophoresis, wherein because a particle size of nanosphere particles is much smaller than that of the nanonail, and a movement speed of the nanospheres is much higher than that of the nanonail, so that by using an electrophoresis method impurities comprising the nanospheres are separated from the nanonail to obtain uniformly dispersed silver-gold-silver alloy-type plasmonic nanonails to further achieve the controllable morphology,
• wherein the nanonail comprises a structure composed of the nanorod and the triangular plate, wherein each end of the nanorod comprises a point and the triangular plate is attached to a side of the nanorod.