Preparation Of Filter Paper-based SERS Substrate And Its Application In Detection Of Seminal Plasma

Surface-enhanced Raman scattering(SERS) spectroscopy is a widely accepted analytical method.It has distinct advantages of high sensitivity, rapid detection as well as nondestructive.Therefore, it has gained popularity in the field of biomedicine, environment and food safety. SERS substrate is not only as a carrier for the analyte,but also it is playing an important role in Raman signal enhancement. In this thesis, we mainly focus on the filter paper-based SERS susbstrate, a simple and rapid method for developing high-sensitivity,highly uniform and stable SERS substrate was established.In addition,the filter paper SERS substrate was applied in the detection and analysis of human seminal plasma.The main research results are as follows:1.The enhancing performance of filter paper SERS substrate prepared by soaking method under different treatment was studied.Firstly, the distribution of silver nanoparticles(AgNPs) on the surface of paper substrate treated with or without NaCl solution as well as different soaking time was analyzed by scanning electron microscope (SEM), then R6G was selected as probe melecule to characterize the sensitivity, uniformity and time stability.Our results demonstrate that both the concentration of NaCl solution and the soaking time play significant roles inthe the distribution of AgNPs onfilter paper surface. The enhancement factor(EF) value of filter paper substrate pretreated with NaCl solution by soaking with concentrated silver colloid for one to two hours is up to 2107, and the limitation of detection(LOD) for R6G solution is 10-7M, showing that the SERS substrates have high detection sensitivity.In addition,these SERS substrates pretreated with NaCl solution also have good uniformity and time stability compared with those without any pretreatment.2.The filter paper SERS substrate was employed for the characterization and detection of seminal plasma.The intensity of characteristic Raman peaks and their corresponding relative standard deviation (RSD) value were utilized to evaluate and compare the enhancement effect of filer paper substrate under different treatment parameters. The reliability and uniformity of the paper substrates were evaluated. The results show that the filter paper pretreated with 20 mM NaCl solution under one to twohours of soaking in silver colloid will give excellent performance.This exploratory work suggests that a reliable filter paper SERS susbtrate can be easily fabricated through soaking, and the preparation time can be sharply reduced after pretreating with NaCl solution. This highly sensitive,uniform and stable filter paper substrate will have great potential in the practical application such as the identification of body fluid trace at crime scenes, detection of environmental pollutants and pesticide residues.