Noninvasive nasopharyngeal cancer screening via salivary DNA detection using label-free surface-enhanced Raman spectroscopy.

Nasopharyngeal carcinoma (NPC) is a malignant tumor originating from the mucosal epithelium of the nasopharynx, which has a high incidence in southern China and Southeast Asia, and is often delayed in diagnosis due to insidious early symptoms. Currently, the diagnosis of NPC mainly relies on invasive tissue biopsy and pathologic analysis, which is not only time-consuming and complicated, but also not applicable to large-scale population screening. In this study, a silver nanoparticle-based surface-enhanced Raman spectroscopy (SERS) platform was established to identify DNA differences in saliva from NPC patients and healthy individuals. By applying the aggregation agent (MgSO4), high-quality SERS signals of nucleic acid can be obtained with even single base resolution. The feasibility was also verified by combining standard DNA sequences and real samples, and a machine-learning-based classification model was established for NPC identification, achieving the sensitivity of 73.8 % and the specificity of 76.7 %. The results show that the proposed method based on saliva SERS combined with machine learning would be a promising tool for noninvasive NPC screening.