Surface-enhanced Raman Spectroscopy Of Serum Protein Purified With Cellulose Acetate Membrane

Surface Enhanced Raman Scattering(SERS)has some advantages with overcoming the limitations of traditional Raman spectroscopy,which can increase the standard Raman intensity by 9-14 orders of magnitude and effectively quench the fluorescence that commonly seen in biological samples.In recent years,SERS technology has been applied to the fields of biology and chemistry by many researchers.Cellulose acetate(CA)membrane has been widely used in the separation and purification of serum proteins due to its advantages of uniform pore size,excellent interception,stable chemical properties and rapid filtration.The purpose of this study is to establish a non-invasive and free-labeled cancer screening method,which was performed for the biochemical analysis of serum proteins purified by CA membrane combined with silver nanoparticles surface-enhanced Raman spectroscopy.The main research work is as follows:The serum samples of liver cancer were smear on the soaked CA film with a sampler and placed in the electrophoresis tank.After the completion of electrophoresis,one of the CA films was dyed and rinsed.Taking the position of staining as reference,the unstained CA film was cut off,and then glacial acetic acid was added.Finally,it was mixed with silver glue,and the supernatant was collected for SERS measurement.The spectral peaks of liver cancer serum protein and normal serum protein were analyzed and the differences between them were compared.Principal component analysis(PCA),as a spectral dimensionality reduction approach,which combined with linear discriminant analysis(LDA)algorithm for classification.In order to test the accuracy of the classification,the posterior probability analysis and receiver operating characteristic(ROC)curves were done.The results showed that the specificity and sensitivity of liver cancer samples and normal samples were 96.7% and 96.7% respectively.In this study,the integral area under the ROC curve for differentiating HCC from normal people was 0.994.Since the traditional membrane electrophoresis experiment is time-consuming,in order to improve this problem,a fast and simple screening method is realized by simplifying the experimental steps.First of all,the serum samples of liver cancer and breast cancer were smeared on the dry CA membrane,and then cut off after absorption.After adding glacial acetic acid,the serum samples were mixed with silver glue.Then the supernatant was collected for SERS detection.The spectral peaks between liver cancer serum protein and normal serum protein,breast cancer serum protein and normal serum protein were analyzed.And the differences between liver cancer serum samples and normal serum samples and breast cancer serum samples and normal serum samples were compared respectively.The specificity and sensitivity of PCA-LDA in the detection of HCC serum samples and normal serum samples were 91.1% and 95.2%,respectively.The integral area under the ROC curve for differentiating HCC from normal blood samples was 0.971.The specificity and sensitivity of PLS-SVM were 97.8% and 90% respectively in the detection of liver cancer samples and normal samples,and the diagnostic accuracy was 94.7%.This exploratory study shows that the combination of CA membrane purified serum proteins and SERS technology has great potential in cancer screening.