Two-dimensional derivatives obtained by oxidation of MXene for simulating the oxidative properties of natural enzymes

Abstract

Oxidation-derived nanoparticles (CDs/TiO x ) of Ti3C2 were prepared for the first time by simple oxidation of Ti3C2. CDs/TiO x was a two-dimensional hybrid of amorphous carbon and titanium oxides with a lateral dimension of about 50 nm. H2O2 was used as the oxygenator and the reduction product was H2O, which was environmentally friendly and inexpensive. Carboxyl, carbonyl, and hydroxyl groups are formed naturally during the oxidation derivative process. The decreased size increases the specific surface area and provides the possibility for the abundant presence of functional groups. The oxidation process converts MXene from reducing to oxidizing and achieves the ability of the derivatives to mimic peroxidase. Compared with natural horseradish peroxidase, the Michaelis constant for H2O2 was ten-fold lower. A cascade catalytic reaction system of glucose oxidase with CDs/TiO x was constructed, and the generated H2O2 could be further used to catalyze the oxidation of nicotinamide adenine dinucleotide (NADH) to NAD+. With the assistance of NAD+-dependent dehydrogenase, NADH could be restored to 95% of the initial level. This assay system can detect glucose levels scientifically and accurately in the range of 0.02–10 mM and remains viable after 20 cycles.