Self-exothermic reaction assisted green synthesis of carbon dots for the detection of para-nitrophenol and beta-glucosidase activity

A rapid, green synthesis strategy assisted by a self-exothermic reaction was designed to prepare highly luminescent carbon dots (CDs) from Ganpu tea infusion (G-CDs) within 5 min using H2O2 and diethylenetriamine (DETA) as the exothermic reactants. G-CDs were successfully obtained through a self-exothermic reaction The prepared G-CDs exhibited clear excitation-dependent characteristics and displayed a strong ultraviolet fluorescence emission (385 nm) at the excitation wavelength of 320 nm. The fluorescence of G-CDs was quantitatively quenched by paranitro-phenol (p-NP) with a concentration range of 0.05-50 mM through inner filter effect (IFE). Since p-NP is one of the hydrolysates of the substrate pNPG under the action of Beta-glucosidase (beta-Glu), a new fluorescence assay was developed for the indirect determination of beta-Glu activity. The detection limits of G-CDs based fluorescence assays are 14.6 nM for p-NP and 0.074 U.L-1 for beta-Glu activity, respectively. The developed fluorescence assays were successfully applied to the detection of p-NP in water and human urine samples and beta-Glu activity in fruit samples with satisfactory results. (C) 2023 The Author(s). Published by Elsevier B.V. on behalf of King Saud University.

Automated summary

A rapid, green synthesis strategy was developed using H2O2 and DETA as exothermic reactants for the preparation of highly luminescent carbon dots (G-CDs) from Ganpu tea infusion. The obtained G-CDs exhibited excitation-dependent characteristics and strong ultraviolet fluorescence emission. A new fluorescence assay was developed for the indirect determination of beta-Glu activity based on the quenching effect of p-NP on G-CDs fluorescence.