A compact prism-based microscope for high sensitive measurements in fluid biopsy

The increasing demand for sensitive, portable, and cost-effective disease detection methods has raised significant interest in the development of biosensors for rapid and early-stage diagnosis, population mass-screening, and bedside monitoring. Although a certain number of sensing devices with high sensitivity has experienced considerable progress, their practical application has been hindered by challenges in replicating instrumental systems, obtaining rapid and multiplexed signals, and the high cost of manufacturing. In response, we present a streamlined prism-based Total Internal Reflection system which, in combination with surface functionalization techniques on gold nanoparticles, is capable of facilitating Evanescent Wave scattering for the highly sensitive and rapid detection of specific analytes in synthetic liquids and real human samples. The system achieves a remarkable limit of detection of 1 fg/mL concentration for the targeted pathological biomarker. Our innovative design addresses the limitations of existing technologies by reducing costs, minimising overall size, and ensuring swift biofluid analysis with remarkable sensitivity. To validate its efficacy, we conducted scattering experiments in synthetic and human serum samples, exploiting functionalized AuNPs to recognize bacterial lipopolysaccharides as biomarkers for sepsis disease. The cohesive integration of these techniques hopefully makes this biosensing setup a promising candidate for potential clinical deployment, meeting the pressing requirements for rapid personalised diagnosis, large-scale population screening and bed-monitoring.