Seeing diabetes: visual detection of glucose based on the intrinsic peroxidase-like activity of MoS2 nanosheets.

Molybdenum disulfide (MoS2) has attracted increasing research interest recently due to its unique physical, optical and electrical properties, correlated with its 2D ultrathin atomic-layered structure. Until now, however, great efforts have focused on its applications such as lithium ion batteries, transistors, and hydrogen evolution reactions. Herein, for the first time, MoS2 nanosheets are discovered to possess an intrinsic peroxidase-like activity and can catalytically oxidize 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to produce a color reaction.

Visual detection of blood glucose based on peroxidase-like activity of WS2 nanosheets.

Tungsten disulfide (WS2) nanosheets were discovered to possess intrinsic peroxidase-like activity and catalyze the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) to produce a color reaction in the presence of H2O2. Based on this finding, a colorimetric method and a portable test kit for the visual detection of blood glucose have been developed by using glucose oxidase (GOx) and WS2 nanosheets-catalyzed reactions. The linear range for glucose was ranged from 5 to 300 μM (R(2)=0.

Graphite-like carbon nitrides as peroxidase mimetics and their applications to glucose detection.

g-C3N4 was found to possess intrinsic peroxidase-like activity, and could catalytically oxidize 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to produce a color reaction. Using g-C3N4 peroxidase-like catalytic activity and glucose oxidase (GOx), a colorimetric method for glucose detection in serum samples has been developed. The linear range for glucose was from 5 to 100 μM (R(2)=0.

Amplified colorimetric detection of mercuric ions through autonomous assembly of G-quadruplex DNAzyme nanowires.

An amplified colorimetric detection of Hg(2+) is proposed by combining T-Hg(2+)-T base pairs and hybridization chain reaction (HCR). Two hairpins consisting of three-fourths and one-fourth of the horseradish peroxidase (HRP)-mimicking DNAzyme in inactive configuration are used as functional elements. In the presence of Hg(2+), one of the hairpins is opened by an assistant probe with the help of T-Hg(2+)-T base pairs and this triggers an autonomous cross-opening of the two hairpins using the strand displacement principle, resulting in the formation of DNA nanowires consisting of numerous reunited Q-quadruplex DNAzyme units.