Studying On The Preparation Of Nanomaterial Surface Enhanced Raman Scattering Sensors For Aminoglycoside Antibiotics Detection And Mechanism

In recent years,antibiotic drug residues in meats and foods has become a concern for consumers.Aminoglycoside antibiotics（AAs）is currently one of the most widely used and effective antibiotics in the treatment of animal infectious diseases,due to its ability to kill bacteria rapidly by interfering with protein synthesis in bacteria.However,long-term intake of meats,eggs,milk and other foods containing AAs residues can cause a range of health problems for humans including dizziness,nausea,tinnitus,increased drug resistance,kidney damage and auditory nerve damage.Accordingly,sensitive methods are needed for the detection of AAs in foods.Ever since the pioneering discovery by Fleischmann et al.in 1974 that high-quality Raman spectra of monolayer pyridine molecules could be obtained from rough silver electrodes,surface-enhanced Raman spectroscopy（SERS）has grown as an analytical technique for the detection and quantification of molecules and ions.SERS is a spectroscopic technique that utilizes inelastic scattering of monochromatic laser light,providing information about molecular structure and chemical composition.Increasingly SERS is finding application in food safety and drug detection owing to its rich fingerprint information,high sensitivity and non-destructiveness as a testing method.The key to the application of SERS technology is to prepare SERS substrates with strong enhancement effect to exert unparalleled advantages in detection sensitivity.In addition to the high sensitivity given by the substrate,SERS technology often needs to meet the different requirements of selectivity,stability,signal reproducibility,and green environmental protection in practical detection applications.The aim of this study is to utilize the signal amplification ability of SERS technology endowed by sensitizing materials,combined with specific recognition tools such as the aptamer（Apt）and DNAzyme,to construct a variety of SERS sensors for trace analysis of AAs in food,so as to meet different requirements of SERS detection.The main research results are as follows:（1）A novel SERS sensor for the ultrasensitive detection of kanamycin based on a Zn-doped carbon quantum dot catalytic switch controlled by nucleic acid aptamer and size-controlled gold nanorodsIn this study,a novel SERS sensor was developed for the ultrasensitive determination of kanamycin in foods.The sensor used two distinct signal amplification strategies,namely the surface plasmon resonance of gold nanorods and a Zn-doped carbon quantum dots catalytic cascade oxidation reduction reaction switch controlled by a nucleic acid aptamer.Under optimized experimental conditions,the SERS sensor demonstrated a linear range of 10^-12to10^-5g m L^-1for the detection of kanamycin,with a limit of detection of 3.03×10^-13g m L^-1.Experiments with antibiotics structurally similar to kanamycin revealed that the sensor had excellent selectivity.Milk powder and honey samples spiked with kanamycin were assayed,with recoveries ranging from 84.1%to 107.2%and a relative standard deviation of 0.74%to2.81%being obtained.Quantification of kanamycin in milk samples revealed no significant difference between the results obtained with the sensor and by HPLC.（2）Ultra-sensitive detection of streptomycin in foods using a novel SERS switch sensor fabricated by AuNRs array and DNA hydrogel embedded with DNAzymeDetrimental health effects caused by the intake of food contaminated with streptomycin have drawn concerns on effective monitoring using sensitive and selective methods.In this work,a DNA hydrogel SERS sensor was successfully developed for the ultrasensitive determination of streptomycin residues in foods.The sensor used a DNA hydrogel containing DNAzyme（Pb-DNAzyme）,triggering release of the Raman reporter 4-mercaptobenzonitrile,which was detected using a gold nanorods（AuNRs）array.The linear range of the sensor was0.01-150 nmol L^-1and the limit of detection was 4.85×10^-3nmol L^-1.Tests conducted with four streptomycin structural analogues confirmed the sensor was specific.Milk and honey samples spiked with streptomycin were analyzed,resulting in standard recoveries in the range98.2%-117.3%.These findings demonstrated that such a sensor can be used for ultrasensitive detection of streptomycin in foods.（3）Performance evaluation of novel Ag@GO-biomaterial SERS substrates for the ultrasensitive detection of neomycin in foodsMany biomaterials are hydrophobic,making them attractive materials for the fabrication of SERS substrates.Herein,we prepared a series of novel SERS substrates by loading graphene oxide（GO）and silver nanoparticles onto four different hydrophobic biomaterials（rose petals,lotus leaves,cicada wings or dragonfly wings）.The obtained Ag@GO-biomaterial SERS substrates offered outstanding SERS performance.These substrates utilized both the electromagnetic mechanism and chemical mechanism to boost the SERS signal,as well as the concentrating effect owing to the hydrophobicity of biomaterials.The Ag@GO-rose petal SERS substrate showed the strongest signal enhancement capability,offering an LOD of 4.52×10^-11mol L^-1for the detection of the neomycin.Results encourage the wider use of hydrophobic biomaterials in SERS substrate construction and hazard monitoring.（4）Synthesis of a photoself-cleaning and recyclable trihybrid hydrophobic paper-based separation channel and its application in SERS separation and detection of aminoglycoside antibioticsIn this study,alkylenone dimer（AKD）-modified filter paper was coated with Zn O@Cu O@Ag to prepare the photoself-cleaning separation channel based on hydrophobic paper for simultaneous separation and detection of three AAs.The kinetic function and principle of the photocatalytic process were discussed.The results show that semiconductor doping can effectively change the overall electron density,promote the charge transfer and vibration coupling,greatly inhibit the recombination of electron-hole pairs,and improve the light utilization rate by broadening the spectral response.After modification with the Zn O@Cu O@Ag,the hydrophilic separation channel showed highly recoverable SERS detection activity and stability.The hydrophobic separation channel could realize the simultaneous separation and detection of amikacin,streptomycin and gentamicin,and the detection limits were 9.11×10^-8,5.91×10^-9and 7.18×10^-9g m L^-1,respectively,which met the needs of practical detection.The SERS signal intensity did not change significantly after the channel was reused for 5 times through the photoself-cleaning effect,which achieved the reusability of SERS substrate.