Plasmonic assay for amplification-free cancer biomarkers detection in clinical tissue samples.

Developing countries have seen a rise in cancer incidence and are projected to harbor three-quarters of all cancer-related mortality by 2030. While disproportionally affected by the burden of cancer, these regions are ill-equipped to handle the diagnostic caseload. The low number of trained pathologists per capita results in delayed diagnosis and treatment, ultimately contributing to increased mortality rates. To address this issue, we developed a point-of-care (POC) plasmonic assay for direct detection of cancer as an alternative to pathological review. Whereas our assay has general applicability in many cancer diagnoses that involve tissue biopsies, we use head and neck cancer (HNC) as a model system because these tumors are increasingly prevalent in lower-income and underserved regions, due to risk factors such as smoking, drinking, and viral infection. Our method uses surface-enhanced Raman scattering (SERS) to detect unique RNA biomarkers from human biopsy samples without the need for complex target amplification machinery (e.g., PCR), making it time and resource-efficient. Unlike previous studies that required target amplification, this work represents a significant advance for HNC diagnosis directly in clinical samples, using only our SERS-based assay for RNA biomarkers. In this study, we tested our assay on 20 clinical samples, demonstrating the accuracy of the method in the diagnosis of head and neck squamous cell carcinoma. We reported sensitivity of 100% and specificity of 97%. Furthermore, we used a handheld Raman device to read the results in order to illustrate the applicability of our method for POC diagnosis of cancer in low-resource settings.