Coordination-induced structural changes of DNA-based optical and electrochemical sensors for metal ions detection

Metal ions play a critical role in human health and abnormal levels are closely related to various diseases. Therefore, the detection of metal ions with high selectivity, sensitivity and accuracy is particularly important. This article highlights and comments on the coordination-induced structural changes of DNA-based optical, electrochemical and optical-electrochemical-combined sensors for metal ions detection. Challenges and potential solutions of DNA-based sensors for the simultaneous detection of multiple metal ions are also discussed for further development and exploitation.

Microfluidic chip for droplet-based AuNP synthesis with dielectric barrier discharge plasma and on-chip mercury ion detection

This study presents a novel microfluidic chip that can achieve on-demand gold nanoparticle (AuNP) synthesis using atmospheric pressure helium plasma and on-site mercury ion detection. Instead of using conventional chemical reaction methods, this chip uses helium plasma as the reducing agent to reduce gold ions and to synthesize AuNP, such that there is no residual reducing agent in the solution after removing the external electric field for plasma generation. The plasma discharge, gas–liquid separation, liquid collection and mercury ion detection can be achieved by this proposed microfluidic chip. The synthesized gold nanoparticles are further functionalized by 3-mercaptopropionic acid (3-MPA) for mercury ion detection. The 3-MPA-capped gold nanoparticles aggregate and result in a colour change of the solution due to the existence of Hg²⁺. The absorption spectra of the solution shifts from red to blue due to the cluster aggregation. The concentration of Hg²⁺ can be quantitatively determined by UV-Vis spectrometry, and the limit of detection was found to be 10⁻⁶ M (0.2 ppm). This developed integrated microfluidic device provides a simple and on-demand method for synthesis of AuNPs and Hg²⁺ detection in a single chip.

This study presents a novel microfluidic chip that can achieve on-demand gold nanoparticle (AuNP) synthesis using atmospheric pressure helium plasma and on-site mercury ion detection.

Carbon nanostructures in biology and medicine

Carbon nanostructures have unique physical, chemical, and electrical properties, which have attracted great interest from scientists. Carbon dots, carbon nanotubes, graphene and other carbon nanomaterials are being successfully implemented in electrochemical sensing, biomedical and biological imaging.

A highly sensitive glutamic acid biosensor based on the determination of NADH enzymically generated by l-glutamic dehydrogenase

In this article, a sensitive and stereo-selective biosensor for l-glutamic acid (l-Glu) based on the electrochemiluminescence (ECL) of Ru(bpy)₃²⁺ has been designed by applying l-glutamic dehydrogenase (GLDH) for enzymatic generation of NADH in situ.