Porous silicon-based fluorescent nanoprobe for the detection of anthrax biomarker and its practical sensing applications

Abstract

Anthrax is an infection caused by bacterium Bacillus anthracis (B. anthracis), and is an old disease that poses a new threat to humans as a biological weapon. Gram-staining and polymerase chain reaction (PCR)-based assays of specimens are standard diagnostic tools for anthrax, but it is time-consuming and limited for the on-site application. In this study, we disclose a porous silicon-based nanoprobe for the detection of dipicolinic acid (DPA), which is a crucial biomarker of the anthrax spore, and its practical sensing applications. The surface of the porous silicon nanoparticles (pSiNPs) was functionalized with multiple amine arms, via a ring-opening click amination and was grafted with terbium ion (Tb3+). A double antenna effect from DPA and pSiNPs to Tb3+ was appeared dramatically and was accompanied by a significant fluorescence enhancement that had high selectivity, sensitivity, and fast response time. The resulting pSiNPs-Tb formulation was used to detect DPA in real water samples and the stimulated Bacillus subtilis (B. subtilis) spores. Besides, the DPA sensing application on the cellulose-based paper was successfully demonstrated as a real-time on-site sensing kit. We believe the demonstrations in this study could encourage further applications throughout a wide variety of fields.