In-situ formed silicon nanoparticles as high-fidelity fluorometric probe for sulfatase activity assay

Analyte-triggered fluorometric nanosensors is desirable for establishing novel analytical tools with better sensing responses. In this study, we illustrated that pyrocatechol (PCT) easily reacted with (N-[3-(trimethoxysilyl) propyl]-ethylenediamine) (DAMO) to generate strong yellow fluorescent silicon nanoparticles (Si NPs). Based on this and the sulfatase-activated conversion of pyrocatechol sulfate (PCTS) into PCT, we designed a sensing approach using PCTS/DAMO encountered fluorescence turn-on for sulfatase activity assay. Through such simple and accessible sensing method with clear reaction mechanism, the designed probe revealed high detection performance with excellent sensitivity and selectivity towards sulfatase compared to the rest of enzymes. The sulfatase activity was measured in a linear range of 0.2-60 U/L, with a detection limit of 0.12 U/L. For real samples study, sulfatase activity was measured in fetal bovine serum and human serum albumin with successful recoveries. Furthermore, the designed sensing method was used for sulfatase inhibitor screening using estrone-3-O-sulfamate (EMATE) as a model.