Study Of The Detection Of Drugs On Site Using Surface-enhanced Raman Spectroscopy Technology

Nowadays, the abuse and spread of drugs has been an increasingly grim problem in the world. Therefor, it is greatly significant to detect drugs for fighting against drug crimes and stopping the drug trade, especially the detection of drugs on site. It can provide direct evidence for policemen. Drugs detection on site including the seized drugs on crime scene and drugs in human body fluid. Recently, surface-enhanced Raman spectroscopy (SERS) has attracted tremendous interest for its rapid, non-destructive examination and ultra-sensitive detection of single molecule and has been applied in the field of biosensing, monitoring micro chemical behavior and single-molecule detecting. However, the applications of SERS mainly focus on fundamental research in lab as well as drug detection. The application of SERS on site need to meet the following requirements:firstly, the substrate is low-cost and portable, then the instrument is micro-volume and the detection result is easily available. It is of great importance of detecting drugs on site not only in obtaining evidence of crime rapidly, but also facilitating the practical application of SERS.At first, we reviewed the history, enhancement mechanism and main application fields of SERS in chapter1. And some methods of detecting drugs were introduced. As we need suitable substrates for field application, the progress from traditional substrate supported on silicon or glass to applied substrate based on paper also presented.In chapter2, we showed drugs detection in the simulative crime scene using inkjet-printed paper substrate. We discussed the conditions such as the number of printing, the selection of paper and the modification of paper in detail and also observed the reproducibility, selectivity and stability of this paper-based substrate. Then we focused on the study of detecting drugs at the crime scene.In chapter3, we presented that detection of drugs in human urine with a rapid-prepared self-assembled AuNRs. Firstly, AuNRs with appropriate ratio was prepared for matching the excitation wavelength of portable Raman instrument and assembled using mPEG-SH. we obtained SERS signal with a method called D-SERS, which was invited by our group with ultra-sensitivity and high stability. The signal is highly reduplicative and we detected different kinds of drugs successfully with D-SERS.In chapter4, we drew help from the support vector machine (SVM), a learning machine, which can classify different samples perfectly. Use the classification result to develop a database and compare the unknown sample’s detecting data with database, then we can get the result rapidly. We detected the drugs in urine of real dragsters successfully with a high accuracy with SVM and achieved the goal of the result’s visualization.Through the above studies, we achieve the goal of detecting drugs on site both in crime scene and human urine and also promote the practical application of SERS.At last, we summarize this work and propose the outlook for future research.