Graphene oxide-manganese oxide composite as an electrocatalyst for simultaneous detection of manganese- and chromium-contaminated water.

The development of a sensitive and selective electrochemical sensor for simultaneous quantification of manganese (Mn(II)) and chromium (Cr(VI)) using composite of graphene oxide (GO) and manganese oxide modified screen printed carbon electrode (GO-MnO/SPCE) is reported for the first time. The good sensing performance is achieved by mixing GO prepared by modified Hummer's method (GO-H) with proper particle size of MnO (241 nm). The mechanism of this sensor is based on the formation of Mn-O and Cr-O on the modified electrode with assistance of oxygen moieties provided by both MnO NPs and GO.

Nanocellulose Films to Improve the Performance of Distance-based Glucose Detection in Paper-based Microfluidic Devices.

We report on a simple, cost-effective, instrument-free, and portable distance-based paper device coupled with NFs for the determination of glucose. The analysis reaction is based upon the oxidative etching reaction of silver nanoparticles (AgNPs) in the presence of HO that is produced from glucose after a glucose oxidase (GOx) catalytic reaction leading to a morphological transformation of AgNPs. A color band length of AgNPs is coated on to a detection channel and then etched by HO, and these were changed from a purple color to colorless as a correlate of the glucose concentration.

Sensitive distance-based paper-based quantification of mercury ions using carbon nanodots and heating-based preconcentration.

This article reports the first fluorescent distance-based paper device coupled with an evaporating preconcentration system for determining trace mercury ions (Hg) in water. The fluorescent nitrogen-doped carbon dots (NCDs) were synthesized by a one-step microwave method using citric acid and ethylenediamine. The fluorescence turn-off of the NCDs in the presence of Hg was visualized with a common black light, and the distance of the quenched fluorescence correlated to Hg concentration.