Surface-enhanced Raman Spectroscopy For Gastric Cancer And Normal Serum

Gastric cancer is one of the most common malignant tumors with highrecurrence rate and mortality rate in China, and more and more young people sufferfrom gastric cancer. The early diagnosis of gastric cancer can be effectively improvedthe survival of gastric cancer treatment, and of great significance to improve thequality of life. In diagnosis process, to determine gastric cancer rapidly andnoninvasively not only can promote the progress of gastric cancer treatment at thepresent stage, also create a new method and technology will provide technical supportfor other malignant tumor diagnosis. Surface-enhanced Raman spectroscopy （SERS）,which can enhance about14order of magnitude than normal Raman spectrum, has thevery high detection sensitivity, have much richer information than the fluorescencespectrum, and the Raman signal does not exist between the fluorescence spectrum ofserious overlap. The aim of this study is to detect gastric serum and laying a solidfoundation for distinction cancerous and normal serum with SERS.The SERS spectra based on gold nanoparticles of serum are measured in thispaper. The results show that the enhancement effect is obvious; comparing withRaman scattering, which only can be found sign signal at1004cm^-1, the SERS ofserum have much more enhanced signal, such as491cm^-1,637cm^-1,725cm^-1,816cm^-1,893cm^-1,959cm^-1,1004cm^-1,1031cm^-1,1094cm^-1,1245cm^-1,1130cm^-1,1207cm^-1,1325cm^-1,1392cm^-1,1443cm^-1,1571cm^-1and1652cm^-1. Comparing the SERSspectrum of several common biomacromolecule, the vibration mode andcharacteristics of belonging have been determined in the signal peak positions, Ramansignal of the serum SERS spectrum is mainly attributable to amino acid, next nucleicacid, carbohydrate and lipid. The signal intensity based on gold-colloid film is higher than gold colloid, but the enhancement effect of individual peak is different, whichmainly because colloid nanoparticles adsorbed on the quartz plate are so unevendistribution that the spectral peak signal with noise interference when serumcombined with gold nanoparticles.Compared with the normal serum, the gastric cancer serum have higner intensitiesat493cm^-1,551cm^-1,636cm^-1,653cm^-1,723cm^-1,1094cm^-1,1127cm^-1,1237cm^-1,1445cm^-1and1651cm^-1, but lower at1004cm^-1,1029cm^-1and1127cm^-1, and noobvious difference at863cm^-1,961cm^-1and1368cm^-1. The results indicate that thereare higher content of nucleic acides and lower content of most of proteins. But in theSERS of gastric cancer, there is a high signal at551cm^-1that belong to tryptophan,which indicate that the content of tryptophan is higher in gastric cancer serum.Medical research show that because of cancer, cancer cell have the ability to infiniteproliferation and consume a large amount of protein for energy that that the content ofnucleic acid is much higher in gastric cancer serum.Combined with multivariate statistical analysis method, the principal componentanalysis based on linear discriminant analysis （PCA-LDA） is used to classify thespectra of normal and malignant serum, specificity and accuracy of tissues are86.1%,96.2%and92.1%, respectively. and classify the spectra of normal and malignanttissues, The sensitivity, specificity and accuracy of tissues are85.5%,90%and89.3%,respectively. This work demonstrated the SERS techniques can be useful for gastriccancer detection, and it is also a potential technique for accurately identifyingcancerous tumor, which is of considerable clinical importance to real-time diagnosis.