Nanostructured Tin and Titanium-Based Sensors to Detect Volatile Colorectal Cancer Biomarkers from Human Biopsies and Immortalized Cell Lines

Colorectal cancer represents a global health burden, being the third most fre-quently diagnosed cancer worldwide, counting about 1.9 million new cases annually, and the second leading cause of cancer-related deaths, counting over 900,000 deaths per year. These figures highlight the urgent need for innovative and non-invasive methods for early detection to improve current diagnostic approaches. In this study, two nanostructured chemoresistive gas sensors based on tin oxide–titanium oxide compo-sites were selected to detect the metabolic patterns associated with human healthy and colorectal cancer tissues. As an additional validation of the biopsy-derived results, the sensors were tested on two colorectal cancer-derived cell lines, namely Caco-2 and RKO. Both sensors demonstrated a clear ability to discriminate between healthy and cancerous samples, with discrimination powers of 11% and 8%, respectively. These results were further confirmed by principal component analysis (PCA), which showed a reasonable separation between healthy and cancerous samples in both the PC1–PC2 and PC1–PC3 score plots and a hierarchical clustering approach for cell samples. While these sensors cannot identify the specific metabolites associated with cancerous tissue, they outlined a characteristic volatile fingerprint of the samples, enabling reliable dis-crimination between healthy and tumor samples.