High Surface Interface Performance TiO₂（zn O）-based Sers Substrates And Using Them For Drug Residues Detection Of Foods

Objective In order to broaden the application of semiconductor surface enhanced Raman scattering（SERS）technology in the field of practical analysis,this paper realizes the rapid analysis and detection of Rhodamine B（Rh B）in chili powder and antibiotics（enrofloxacin and ciprofloxacin）in egg by regulating the surface and interface properties of semiconductor Ti O₂,which provides a new idea and method for the analysis of harmful residues in food.Methods Ti O₂ NPs were prepared by sol hydrothermal method,and sodium borohydride（Na BH₄）was used to regulate its surface properties to form Ti O₂ with high surface properties and rich in defect state（defined as R-Ti O₂）.In addition,by improving the interface properties of Ti O₂ and compounding it with another semiconductor material Zn O,Ti O₂/Zn O heterojunction with strong coupling can be prepared at the interface.At the same time,taking R-Ti O₂and Ti O₂/Zn O heterojunction as SERS active substrate,Rh B in chili powder and antibiotics in egg white were analyzed qualitatively and quantitatively,respectively,to explore the SERS enhancement behavior of drug molecules on the substrate.The spiked samples were pretreated by the pretreatment operation,and the actual analysis results were further optimized.A method and method for the detection of harmful residues in food based on SERS technology was established.Results The surface modified Ti O₂ NPs（R-Ti O₂）can form a stable suspension in the aqueous phase.However,the untreated Ti O₂ NPs will precipitate rapidly in the water,so it is difficult to exist stably in the aqueous phase.This stable and uniform liquid-phase R-Ti O₂ SERS substrate produces strong SERS signals for dye molecules such as rhodamine 6G（R6G）and crystal violet（CV）.Nevertheless,when R6G and CV molecules are adsorbed on R-Ti O₂ and Ti O₂ solid powders,the Raman characteristic peaks of molecules can not be observed.Using the liquid-phase SERS substrate,the minimum detection concentration of Rh B in chili powder can reach 1×10^-9 mol/L.In the range of1×10^-9-1×10^-5 mol/L,there was a good linear relationship（R²=0.9908）between the logarithm of Rh B concentration and its SERS signal intensity,and the recovery of Rh B was 96.3%-102.4%.The detection limits of enrofloxacin and ciprofloxacin in egg using Ti O₂/Zn O heterojunction substrates were 3.94×10^-8 mol/L and 7.04×10^-8 mol/L,R² of0.9905 and 0.990,respectively,which were far lower than In EU standard（100μg/kg）.Using this method,the recovery of enrofloxacin and ciprofloxacin residues ranges from86.0-98.4%and 83.8-96.0%,respectively.Conclusions In this paper,a new type of semiconductor SERS active substrate was successfully prepared by regulating the surface and interface properties of semiconductor Ti O₂.Rhodamine B（Rh B）in chili powder and antibiotics（enrofloxacin and ciprofloxacin）in egg were detected by surface enhanced Raman scattering（SERS）technology for the first time.The results show that the proposed SERS method can realize the rapid and sensitive detection of harmful residues in food,and the detection results meet the methodological requirements.This not only expands the application scope of semiconductor SERS technology in the field of practical analysis,but also lays a foundation for the detection of harmful residues in food.