Designing Fluorescent Interfaces at Hotspots in a Plasmonic Nanopore for Homologous Optoelectronic Sensing

In this work, a site-selective functionalization strategy is proposed for modifying fluorescent dyes in the plasmonic nanopore, which highlights building optoelectronic dual-signal sensing interfaces at "hotspots" locations to construct multiparameter detection nanosensor. Finite-difference time-domain (FDTD) simulations confirmed the high-intensity electromagnetic field due to plasmonic nanostructure. It is demonstrated that adjusting the distance between the nanopore inner wall and fluorophore prevented the fluorescence quenching, resulting in more than a thirty fold fluorescence enhancement. Upon binding with the target analyte, the sensor produces homologous yet independent optoelectronic dual-signal responses that cross-validate one another, providing highly accurate analysis even in the presence of multiple interferences. The platform demonstrates precise, adaptable detection with linear responses to extracellular pH changes at the single-cell level, making it a versatile tool for a range of biosensing applications. By enabling the functionalization of fluorescent interfaces in the "hotspots" of metal nanopores, this interface design strategy efficiently exploits the enhancement of electromagnetic fields to achieve high-precision dual-signal measurements and greatly improves the sensitivity of biosensing applications.