Highly sensitive wide-range target fluorescence biosensors of high-emittance metasurfaces

We demonstrate highly sensitive fluorescence (FL) biosensors made of plasmon-photon-hybrid high-emittance metasurfaces, which are hybrid structures composed of perforated silicon waveguides and stacked complementary (SC) gold nanostructures. The SC metasurfaces are applicable to a wide range of targets from antibodies to nucleic acids. As a test bed, a representative antibody of immunoglobulin G is immobilized on the metasurfaces through microfluidic paths and then is directly detected in a scaled manner even at a very low concentration of 5 pg mL^-1, i.e., 34 fM. Moreover, a cancer marker of p53 antibody is indirectly detected on the SC metasurfaces at a low concentration of 50 pg mL^-1, which is significantly lower than the medical diagnosis criterion of a few ng mL^-1. Furthermore, single-strand DNAs that are oligonucleotides and complementary to SARS-CoV-2 RNA are detected with 1 h immobilization time in the range of fmol mL^-1 in a scaled manner. These experimental results indicate that the present FL metasurface sensors function efficiently as biosensors for a wide range of biomarkers.