Implantable, Label-Free NIR-Based Porous Silicon Biosensor for Monitoring Biomarkers in Interstitial Fluid

Abstract

The detection of biomarkers in interstitial fluid (ISF) holds significant promise for early disease diagnosis and monitoring. Porous silicon (pSi) offers a versatile platform for implantable biosensors due to its biocompatibility, high surface area, and tunable properties. This study presents the development and characterization of a label-free pSi biosensor featuring a near-infrared (NIR) photonic microcavity (MC) that is implanted subcutaneously in a euthanized mouse to detect insulin in real time for proof of concept. The biosensor demonstrates specific insulin detection ability with a limit of detection (LOD) of 209 nM, exhibiting excellent consistency, reproducibility, and long-term sensing performance. Furthermore, the biosensor demonstrates the capability to detect insulin spiked into plasma obtained from a healthy mouse. It is further reported that a simple and sensitive data analysis method, the effective shift in wavelength (ESW) method for measuring the shift in center wavelength of the photonic MC. This viable approach can be extended to other photonic biosensors where measurements are limited by the resolution of the spectrometer. The proposed approach lays the foundation for the development of pSi-based implantable biosensors for real-time continuous monitoring of clinically relevant biomarkers in vivo for chronic disease management.