A novel and portable electrochemical sensor for 5-hydroxymethylfurfural detection using silver microdendrite electrodeposited paper-based electrode.

A portable paper-based electrochemical sensor has been developed to determine 5-hydroxymethylfurfural (5-HMF). A screen-printed carbon electrode (SPCE) was facilely fabricated for the first time on poster paper which showed a very satisfactory electrochemical response. The analytical performance of the electrode was enhanced by electrochemical deposition of silver microdendrites (AgMDs).

A facile colorimetric aptasensor for low-cost chlorpyrifos detection utilizing gold nanoparticle aggregation induced by polyethyleneimine.

A colorimetric aptasensor for chlorpyrifos detection utilizing the localized surface plasmon resonance (LSPR) of gold nanoparticle (AuNP) aggregates coupling with a specific aptamer and cationic polyethyleneimine (PEI) has been developed. The measurement principle is based on a remarkable characteristic of AuNPs that can change their colors under the aggregation and dispersion conditions, which enables a sensitive colorimetric detection. In the absence of chlorpyrifos, negatively charged phosphate backbones of the aptamer potentially interact with the cationic PEI, resulting in the red color appearance of the dispersed AuNPs, whereas, in the presence of chlorpyrifos, the aptamer binds explicitly to chlorpyrifos, consequently releasing cationic PEI.