Nanostructured Porous Silicon/Carbon Dots–Hybrid for Orthogonal Molecular Detection

Optical sensors and biosensors have gained significant interest in light of their sensitivity, speed of measurement, and label-free detection capabilities. To date, most reported optical biosensors employ a single-mode transduction mechanism e.g., fluorescence, reflectivity or scattering. Sensing and biosensing designs using dual-mode transducer elements, however, can significantly improve the sensing performance, versatility, and selectivity. Specifically, integration of different optical modalities within a single biosensor platform might provide complementary and enhanced sensing information. Herein, we report on the fabrication of a new hybrid guest-host material, consisting of a Fabry–Pérot porous silicon (PSi) thin film, a nanostructured inorganic scaffold, encapsulating fluorescent carbon quantum dots (C-dots). The hybrid is synthesized by a facile in-situ pyrolysis of the carbonaceous precursor infiltrated into the nano-scale pores of the inorganic host. We show that the resulting hybrid allows for label-free optical detection of target molecules using orthogonal modalities i.e., the white light reflectivity of the PSi and the fluorescence of the C-dots, and these two signals can be observed and collected simultaneously. We demonstrate that resulting sensing platform exhibit enhanced sensitivity, improved linear response, as well as a wider dynamic range in comparison to single components.