Common-path interferometric label-free protein sensing with resonant dielectric nanostructures

摘要

Biosensors: Nanostructures team up to turn down the noise Portable devices that spot biomarkers in a patient's bloodstream stand to benefit from a photonic microchip that can achieve ultra-low detection limits. Isabel Barth from the University of York in the United Kingdom and colleagues designed a biosensor based on guided-mode resonances, a phenomenon that uses laser light to switch on strong resonant signals inside nanoscale gratings. The researchers improved this technology by simultaneously exciting two resonant modes with a low-cost laser diode. This approach enables sensing of protein-antibody binding induced refractive index changes using relative phase differences between the two modes, minimizing the impact of noise due to outside sources including mechanical vibrations. The team demonstrated label-free detection of procalcitonin, a key biomarker for bacterial infections, at picogram/milliliter scales, which could, for example, be relevant in the context of bacterial co-infections of COVID-19 patients.