The present method provides a facile and rapid route to the large-scale synthesis of 3D AgMSs with nanotextured surface morphology. The GNPs were HSP990 research buy successfully assembled on the clean rough surface of AgMSs via the interaction between the carboxyl groups of GNPs and the silver atoms of AgMSs (Figure 1). Figure 1 Schematic representation of the self-assembly between gold nanoparticles (GNPs)

and Ag microspheres (AgMSs) via the coupling between the carboxyl groups of GNPs and the silver atoms of AgMSs. Methods Experimental section Preparation of gold nanoparticles Briefly, 50 mL (0.2 mg/mL) of chloroauric acid (Sigma-Aldrich) was heated to boiling point, and then 1.2 mL (10 mg/mL) of sodium citrate (Sigma-Aldrich) was added. Boiling lasted for 5 min until the solution became dark red in color. After cooling down to room buy NU7026 temperature, 20 μL of GNPs was used for the analysis using transmission electron microscopy (TEM). Zeta potential of the assemblies prepared at different molar ratios of Ag microspheres to gold nanoparticles Typically, 2.5 mL of 5 mM AgNO3 aqueous solution was added to 95 mL of deionized (DI) water in a 150-mL beaker. Then, 2.5 mL of 5 mM l-AA (Sigma-Aldrich) was added into the above-mentioned

solution under vigorous stirring at room temperature. The JQ-EZ-05 nmr system was stirred vigorously under ambient conditions for 4 h. The color of the solution rapidly changed from colorless to gray. The resulting product was collected by centrifugation, washed three times with DI water and ethanol, and then dispersed in ethanol for further use. Preparation of the assemblies of GNPs to AgMSs AgMSs (10.8 oxyclozanide mg) was dispersed in 0.9 mL of ethanol solution, then 100 μL of different concentrations of GNPs (0.4, 0.2, 0.1, 0.02, and 0.01 mg) were mixed with AgMSs solution under ultrasonic interaction, respectively. After 10 min, the resulting product was collected by centrifugation at 1,000 rpm for 5 min and washed twice with DI water and then dispersed in 1 mL DI H2O for further use. Preparation of Raman samples A total of 200 μL of GNPs to AgMSs (AgMSs@GNPs)

was immersed in ethanol solutions containing 200 μL of 2-mercaptopyridine (2-Mpy) (10 to 7 M) under ultrasound for 10 min. After 2-Mpy molecules (Sigma-Aldrich) were adsorbed on the AgMSs@GNPs, the samples were washed twice with DI water and ethanol by centrifugation and finally dispersed in 10 μL ethanol. Then, an aliquot of 10 μL of 2-Mpy-loaded AgMSs@GNPs in ethanol solution was dropped onto a Si wafer. The dropped solution was spread evenly into a circle. After evaporation of ethanol under the dry N2, the sample was measured by a simple Raman instrument for six times. All of the experiments were carried out at room temperature. Characterization The UV-visible spectra were recorded in a Shimadzu UV-2450 UV-visible spectrophotometer (Shimadzu Co. Ltd.