Fabrication of label-free and eco-friendly ROS optical sensor with potent antioxidant properties for sensitive hydrogen peroxide detection in human plasma.

Abstract Herein, biogenic silver nanoparticles, Cafi-AgNPs was produced based on Cassia fistula-phenolic-rich extract (Cafi) only, without any toxic chemical reagent or organic solvent. Cafi bioactives were characterized using UHPLC-ESI-QTOF-MS/MS analysis. The as-synthesized nanoparticles were characterized using physico-chemical techniques including UV-Vis, TEM, SEM, EDX, FTIR, DLS, Zeta potential, XRD, TGA and DGA. In addition, their antioxidant properties and cytocompatibility on erythrocytes and HEK-293 cells were examined. Results show that Cafi mediated the successful synthesis of stable well-dispersed AgNPs. Cafi-AgNPs demonstrated potent reducing and radical scavenging activities against ABTS˙+, DPPH˙ and NO˙. Furthermore, Cafi-AgNPs was compatible with human erythrocytes and HEK-293 cells. Based on the superior surface plasmonic and biological attributes of Cafi-AgNPs, its potential in H2O2 sensing was evaluated. The proposed sensor demonstrated satisfactory analytical performances with linearity of 10 to 200 µM, detection limit of 3.0 µM for H2O2, and was successfully applied in the detection of H2O2 in human plasma.