Review—Bio-Nanosensors: Fundamentals and Recent Applications

Nanosensors to detect and measure biomarkers are increasingly pervasive in our daily lives. Nanostructured materials provide an unprecedented opportunity to measure ultra-low concentrations (<nM L ⁻¹ ) of target analytes, which in turn enables improved understanding of complex biological processes. Sensors with low detection limits serve multiple roles, most notably for early detection of diseases, containment of infections and viral propagation, monitoring biodata, and food quality control, as well as elucidating high-resolution genome-phenome relationships. Here, we introduce the fundamental components of a bio-nanosensor, including the signal transduction elements and target-selective receptors (e.g., low molecular weight synthetic moieties, or organic molecules such as DNA, enzyme, antibody, etc). We focus on electronic, electromechanical, optical, and electrochemical transducers, and discuss how the advent of nanostructured materials, particularly 2D materials and nanoparticles, have enabled improved performance in terms of biocompatibility, sensitivity, selectivity, wearability, and limits of detection. We present an overview of recent progress in the development and application of nanomaterials for the detection and quantification of biomarkers, along with the pros and cons of the different transduction strategies, and close with a discussion of persisting challenges and opportunities in the field.