Design And Application Of Highly Sensitive Surface Enhanced Raman Scattering Sensor

Surface-enhanced Raman scattering?SERS?analysis methods are widely used in analytical chemistry,surface-interface chemistry and life sciences due to their high resolution,high sensitivity and without sample preparation.In this paper,we designed highly sensitive SERS sensors for the detection of glucose in urine and silver ions in sewage,respectively,for the purpose of improving the detection sensitivity and selectivity of SERS.The main research contents as follows:1.A novel and sensitive sensor for accurate quantitative detection of glucose in urine based on the aggregation of silver nanoparticles functionalized with mercaptophenyl boronic acid was designed.This is the first report of the aggregation of silver nanoparticles modified with SERS probe 4-mercaptophenyl boronic acid using the glucose to be measured.Compared with the conventional test for detecting glucose with phenylboronic acid,the probe molecule 4-MPBA is not required to be further modified,greatly simplified the experimental process.4-MPBA not only has strong SERS activity,but also 2 molecules of 4-MPBA can specifically recognize and bind one molecule of glucose,resulting in the aggregation of Ag NPs.The formation of a"hot spot"can promote the SERS signal of 4-MPBA located just in the nanogap to be significantly enhanced,achieving a highly sensitive quantitative determination of glucose.In addition,accurate determination of glucose concentration in urine indicates that the new glucose nanosensor has great potential in clinical diagnosis.2.A highly sensitive and recyclable surface-enhanced Raman scattering?SERS?chip sensor is designed for the determination of silver ions.It is based on the specific reversible binding between silver ions and glucose oxidase?GOD?.The sensing chip is made by layer-by-layer assembling GOD on a metal nanoparticle-assembled,SERS-active chip with a positive charged polyelectrolyte as a linker.Iso-alloxazine,a chromophore in flavin adenine dinucleotide?FAD?in GOD,coordinates with silver ions,which causes significant variation in SERS spectra of GOD.The reaction shows high sensitivity and selectivity for silver ions with the detection limit of 1.0×10^-10 M.Most significantly,the bonded Ag?I?in GOD can be reduced to Ag?0?by sodium borohydride and the GOD structure can be recovered then.Thus,the chip sensor is recyclable.Merits of using GOD as a novel SERS probe toward Ag⁺are embodied in not only a simplified sensor structure based on its dual role of Ag⁺accepter and SERS signal reporter,but also a nontoxic label to biological systems,indicating that it is promising for tracing Ag⁺in vivo.