Bioelectronics for <i>In Situ</i> Monitoring of Tumor Microenvironment Markers

The tumor microenvironment (TME) is a dynamic and heterogeneous niche that critically shapes cancer progression, immune evasion, and therapeutic resistance. Characterized by gradients in oxygen tension, pH, and metabolic activity, the TME offers a rich yet underexploited source of real-time biomarkers related to cancer. While conventional imaging techniques often lack the temporal resolution and molecular specificity to capture these rapid physiological changes, emerging miniaturized bioelectronics and multiplexed systems carry promise for <i>in situ</i> monitoring of such TME markers with high sensitivity and spatial precision. This article explores such recent advances in this direction, including bioelectronic sensor design, flexible electrochemical devices, organic transistors, and nanostructured interfaces tailored for TME characterization. Further, a discussion of the convergence of bioelectronics with nano-contrast-based molecular imaging is presented, with prospects for developing closed-loop therapeutic systems for cancer. These technologies offer a transformative platform for precision oncology, enabling dynamic, continuous, and localized assessment of tumor biology across preclinical and clinical settings.