Carboxymethyl cellulose-NiO nanoparticles as peroxidase mimic for sensitive colorimetric detection of hydrogen peroxide

A simple co-precipitation method has been used to derive an excellent peroxidase mimetic material, carboxymethyl cellulose-stabilized NiO nanoparticles (C-m-NiONps). CMC provided uniqueness to C-m-NiONps by capping the incipient NiONps as the capping prevented any further agglomeration. Characterization study revealed that the nanoparticles are spherical to oblong in shape (similar to 6 nm size), crystalline in nature, and possess coated morphology. C-m-NiONps exhibited excellent peroxidase mimetic behavior toward H2O2 oxidation of 3,3',5,5' tetramethyl benzidine (TMB) to produce a quick visual response (blue color) within an extremely short time span of 1.5 min. C-m-NiO(c)Nps-catalyzed oxidation of TMB followed Michaelis-Menten behavior toward both H2O2 and TMB and indicated its very high affinity for both H2O2 (K-m = 0.04/mM) and TMB (K-m = 0.194/mM). V-max for the enzymatic reaction is 12.67 x 10(-8) M s(-1) (wrt TMB) which is almost at par with the reported value for HRP. This colorimetric platform exhibited excellent sensitivity (LOD = 0.078 mu M), reproducibility, low-temperature activity (at 35 degrees C), and high selectivity. The catalyst showed high recyclability as it conserved most of its activity even after being used in six consecutive cycles. The colorimetric method could successfully detect the presence of H2O2 levels in milk samples from local market and human serum.

Automated summary

A simple co-precipitation method was used to prepare an excellent peroxidase-like material, which exhibited excellent sensitivity and selectivity in the oxidation reaction of H2O2.