Construction Of Anti-interference SERS Tags And Their Application In Biosensor

In many research fields,quantitative detection of target in samples is an indispensable part.At present,the methods to carry out this step mainly rely on large instruments that are expensive and complex to operate.Therefore,it is necessary to develop low-cost,easy-to-operate,highly sensitive and high-specific detection methods to deal with the limitations of methods that rely on large instruments.The biosensor based on surface-enhanced Raman scattering（SERS）has a broad application prospect in quantitative detection because of its low cost,high sensitivity,strong specificity and easy to operate,and good compatibility of water phase detection.However,there are still several problems in the application of SERS-based biosensor technology in complex biological samples:（ⅰ）in labeling detection,the Raman spectrum of traditional Raman report molecules are overlapping with biomolecules in the spectral range of600-1800cm^-1,which is easy to cause signal interference and difficult to ensure high accuracy;（ⅱ）in labeled-free detection,there are many non-specific adsorption between the molecules in the sample and the surface of the enhanced substrate,which affects the selectivity and reproducibility of the detection;（ⅲ）the random and unstable binding of the Raman reporter molecules and the enhanced substrate will affect the stability of the SERS tags in the detection process.Based on the above,this thesis designs anti-interference SERS tags combined with biological recognition elements,and constructs anti-interference SERS biosensors.The specific research is as follows:（1）preparation and verification of spectral anti-interference SERS tag（Au@4-TEAE NPs）.4-[trimethylsilyl]ethynyl（4-TEAE）aniline is selected as the anti-interference Raman reporter molecule,and the anti-interference Raman characteristic peak is located in 1993 cm-1.SERS labeling with specific recognition function composed of 4-TEAE junction gold nanoparticles（Au NPs）and aptamers,competing bind with the captured substrate and OTA to complete the quantitative detection of OTA.The experimental results show that the anti-interference SERS labeled based biosensor has the advantages of non signal overlap,anti-interference of biological samples,high specificity and high sensitivity,which provides an effective strategy for accurate quantitative detection of negative impurity biological samples.（2）synthesize gold@Prussian blue core-shell enhanced anti-interference SERS tags and optimize it.The surface of gold nanoparticles was etched by potassium ferricyanide containing cyano group,and then Prussian blue shells were grown on the surface of corroded gold nanoparticles by adding two kinds of precursor solutions to synthesize SERS tags.The two main factors affecting the Raman peak strength of SERS tags（the size of gold nanoparticles and the thickness of Prussian blue shell）were optimized,and the anti-interference,signal strength and stability were verified.The results showed that the prepared and optimized SERS tags only had a unique strong Raman peak at 2160 cm^-1,which was much stronger than other anti-interference SERS tags,and had good stability within 110days,which met the detection requirements.（3）An anti-interference SERS tag based biosensor was constructed by using gold@Prussian blue core-shell enhanced anti-interference SERS tag to quantitatively detect the pollution level of chlorpyrifos in biological and environmental samples.The obtained enhanced anti-interference SERS tags surface modified amino group combined with 5’-terminal modified carboxyl aptamers were endowed with the ability to specifically recognize chlorpyrifos,and the quantitative detection of chlorpyrifos was completed together with the capture substrate.The experimental results show that the biosensor based on enhanced anti-interference SERS tag has the advantages of high sensitivity,high anti-interference stability and strong repeatability.