ABSTRACT
Objective: The purpose of the research was to optimize technology for producing a magneto controllable nanocomposite Ag@Fe3O4 with modern physicochemical and therapeutic requirements using methods of mathematical design of the experiment. Methods: To optimize the synthesis process of the nanocomposite Ag@Fe3O4, the method of factor experiment was used. Mathematical calculations were performed using the STATISTICA 10 StatSoft Inc. system and Excel spreadsheet processor of MS Office 2019 Professional Plus. Results: Based on the study of technological parameters of nanocomposite synthesis Ag@Fe3O4 (16 experiments) a regression equation was obtained: Y = 106.415+0.038X1+4.448Х2+1.806Х3–1.593Х4–18.945Х5–109.980Х6. By the use of this equation the synthesis parameters were optimized with the help of steepest ascent method. It was found that the maximum yield of Ag@Fe3O4 can be achieved under the following conditions: X1 (magnetite synthesis time, min)–40; X2 (glucose content in solution,%)–10; X3 (temperature of the Tollens reaction, °С)–65; X4 (magnetite silver coating time, min)–30; X5 (pH, units)–8.5; X6 (rate of addition of ammonia, mol/min)–0.36. Conclusion: Using mathematical design of the experiment, a technology was developed for producing Ag@Fe3O4 with modern physicochemical and therapeutic requirements.
ABSTRACT
Objective To develop a new type of Raman-enhanced substrate for rapid detection of E.coli based on label-free surface-enhanced Raman scattering( SERS) technology.Methods Stober’ s improved method was used to prepare 360 nm silica ( SiO2 ) nanospheres.Prepared gold core-silver shell nanoparticles( Au@Ag) of different size were attached to 360 nm SiO2 to fabricate the nanocomposites ( SiO2-Au@Ag ) that were characterized by transmission electron microscopy (TEM) and UV-visucl light adsorption spectra (UV-Vis).PATP was detected to select SiO2-Au@Ag with optimal SERS effect.This optimal SiO2-Au@Ag was used to obtain the sensitivity of PATP and E.coli detection after a simple mixed culti-vation.Results TEM images showed that Au@Ag aggregated with the size of Au@Ag attached to 360 nm SiO2 .UV-Vis spectra indicated that the maximum absorption of Au@Ag and SiO2-Au@Ag had a red shift with the invrease of Au@Ag size.The experiment results suggested that detection sensitivity of PATP by SiO2-100 nm Au@Ag 10 -10 mol/L, while the lowest detectable E.coli concentration was 105 CFU/ml.Conclusion The 360 nm SiO2 binding with 100nm Au@Ag exhibits great potential for SERS applications.