High Visual Colorimetric Determination of F‐ Ions by Exploiting the Inhibition of Oxidase Mimicking Activity of FeMnO4@GQD Nanocomposite

Abstract

Human health is significantly impacted by fluorides in water.Too much fluoride consumption through drinking water causes chronic dental and bones diseases. A trace number of fluorides in drinking water can be determined, which is immensely vital for human health. In the current study, we have designed a visual colorimetric chemosensor assay using the brilliant oxidase mimicking activity of biosynthesized FeMnO4@GQD nanocomposite. FeMnO4@GQD nanocomposites showed excellent mimicking activity in mild acid medium pH‐5, and obtained a Vmax value of 1.71603×10−6 and an important Km value of 0.0684 mM based on Hanes‐Woolf kinetics. The robust nanocomposites were shown to be significant stability for detecting oxidases under conditions. As a consequence, oxidase‐like activity was inhibited in the presence of fluoride ions. A linear correlation was established by the development of blue colour with fluoride ions concentration and appeared at a low limit of detection of 1.2 μg/ml without interfering with other common ions.

Host–Guest Encapsulation of RIBO with TSC4X: Synthesis, Characterization, and Its Application by Physicochemical and Computational Investigations

“…POD-like activity of the present nanocatalyst RIBO-TSC4X (IC) was evaluated using TMB as the chromogenic substrate with the addition of supplementary oxidant H 2 O 2 in the Hac −NaAc buffer solution (pH −5) under ambient condition followed by our earlier reported method. 39 For the typical reaction, the RIBO-TSC4X complex (250 μM) was added in 380 μM TMB solution (Hac −NaAc buffer pH-5), followed by the addition of 20 mM H 2 O 2 . Then, the solution was incubated for 30 min and recorded the absorbance in UV–visible spectroscopy at 652 nm for monitoring the progress of the reaction.…”

Multienzyme Mimicking Cascade Mn3O4 Catalyst to Augment Reactive Oxygen Species Elimination and Colorimetric Detection: A Study of Phase Variation upon Calcination Temperature

“…The absorbance increases with increasing pH, reaches a maximum at pH −5, and loses activity after pH −7. The blue product turns into yellow TMBdi (λ max = 450 nm; e = 59000 M –1 cm –1 ) at high acidic pH, and the catalyst loses its activity at basic pH. Therefore, pH −5 was considered to be the optimum pH for the present nanozyme.…”

“…Among the artificial nanozymes, POD and oxidase (OD) are in the oxido reductase family and can oxidize organic substrates such as o -phenylenediamine (OPD), 3,3′,5,5′-tetramethylbenzidine (TMB), dopamine, 2,2′,5,5′-azinobis­(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and luminal with the help of H 2 O 2 (POD) and without the involvement of H 2 O 2 (OD). SOD is another kind of antioxidant enzyme that can dismutase the superoxide radical, thereby forming H 2 O 2 , which is also considered to be a powerful reactive oxygen species (ROS). − The nanozymes that can catalyze the POD, OD, CAT, and SOD are directly regulate the intercellular ROS level and therefore are highly applicable in a synergistic artificial antioxidant defense system. A particular ROS level in the body is crucial to maintaining many biological processes, but in diseases and inflammation, the ROS level is disturbed, which can stimulate several other chronic diseases.…”