Surface-enhanced Raman spectroscopy of gastric cancer serum with gold nanoparticles/silicon nanowire arrays

Surface-enhanced Raman spectroscopy (SERS), with high sensitivity and good stability, has been extensively studied and applied in biomedicine, analytical chemistry and clinical diagnosis. In this work, we present the fabrication of gold nanoparticles/silicon nanowire arrays (Au/SiNWA) SERS substrate and the SERS measurement on gastric cancer serum. The Au/SiNWA substrate were synthesized by the noble metal-assisted chemical etching and reduction method. The sensitivity of the Au/SiNWA substrate were tested with rhodamine 6G and it was found that the detection limit for SERS can reach 10−7 M. The Au/SiNWA substrate were then applied to measure the SERS of the serum from gastric cancer patients and healthy persons. The experimental results show that the Au/SiNWA substrate could significant enhance the Raman signal of the serum, and it can be learned that the SERS peaks were mainly belong to protein, nucleic acid, and carbohydrate etc. By comparing the SERS signal of the serum from cancer patients with the serum of normal persons, it was found that the SERS intensities of most nucleic acids of gastric cancer patients were higher and that of proteins were relatively lower, moreover, it was found that the content of tryptophan, phenylalanine and tyrosine in the hemoglobin were significantly lower than healthy persons. The above phenomenon coincided with current conclusion of medical research. Our findings indicate that Au/SiNWA is a suitable SERS-active substrate for distinguishing gastric and normal serum, and it provides a promising approach for rapid, noninvasive and accurate diagnosis of gastric cancer.