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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.

Cyclic voltammograms, at the carbon paste electrode were recorded for α-tocopherol dissolved in surfactant+ethanol+water and surfactant+acetonitrile+water mixed solvent systems containing ammonia. The oxidation potential of the vitamin was found to vary with a change in the surfactant, being more positive in cationic surfactants as compared to the anionic or nonionic surfactants. Differential pulse voltammetric technique was utilized for the determination of the vitamin in the above solvent systems. The limit of detection and the linear range varied in different surfactants, the lowest being in the Triton X-100+acetonitrile+water mixtures. Simultaneous determination of α-tocopherol and ascorbic acid was carried out. Multivitamin–multimineral pharmaceutical preparations analyzed gave satisfactory results.

The voltammetric behavior of Vitamin C (l-ascorbic acid) at carbon paste electrodes and electrodes modified with aza macrocycles have been studied. The use of zinc complexes, formed in situ at the electrode surface reduced the overpotential for the oxidation of ascorbic acid by about 200 mV and enhanced the peak currents. Linearity was observed over the range of 0.6–500g/cm 3 with a detection limit of 0.1g/cm 3 by differential pulse voltammetry. The modified electrode was used for the determination of Vitamin C in multivitamin–multimineral pharmaceutical preparations, fruit juices and wine samples. © 2001 Elsevier Science B.V. All rights reserved.