α-Glucosidase-Triggered Reaction for Fluorometric and Colorimetric Assays Based on the Formation of Silicon-Containing Nanoparticles

Designing analytical approaches for enzymatic activity monitoring with high sensitivity and selectivity is of critical value for the diagnosis of diseases and biomedical studies. In this study, we have created a facile one-step synthetic route to prepare orange-red color and yellow fluorescent silicon-containing nanoparticles (Si CNPs) by mixing 3(2-aminoethylamino) propyl (dimethoxymethylsilane) and hydroquinone (HQ) in an aqueous solution. Inspired by the HQ-regulated facile synthetic step and the generation of HQ from alpha-glucosidase (alpha-Glu)-catalyzed hydrolysis of 4-hydroxyphenyl-alpha-d-glucopyranosyl (4-HP alpha DG), we have designed a straightforward colorimetric and fluorometric alpha-Glu activity assay using a commercially available 4-HP alpha DG as the alpha-Glu substrate. Fluorescent and colorimetric assays for alpha-Glu activity measurement have been thereby established and exhibited detection limits as low as 0.0032 and 0.0046 U/mL, respectively. Under single excitation at 370 nm, the prepared Si CNPs emitted yellow fluorescence at 520 nm and exhibited an absorbance peak at 390 nm. In addition, the proposed approach reveals various advantages including easy operation, time-saving, and good anti-interference ability. Hence, it could improve the progress of fluorometric and colorimetric enzymatic activity assays with high sensitivity and simplicity. Moreover, the proposed approach was applied for alpha-Glu inhibitor screening, and its feasibility in real samples was measured by detecting the alpha-Glu activity in human serum samples.

Automated summary

This study developed a simple synthetic method for silicon-containing nanoparticles and designed a colorimetric and fluorometric assay for detecting alpha-Glu activity. The approach showed high sensitivity and simplicity, making it applicable for enzyme activity assays and inhibitor screening.