Steric paper based ratio-type electrochemical biosensor with hollow-channel for sensitive detection of Zn2+

The construction of flexible platform possessing the functions of immobilizing, separating, rinsing, and high-throughput analysis plays a significant role in biological and clinical research. Herein, hollow- channel technique was integrated with lab-on-paper for the simultaneous determination of two different concentrations of Zn2＋ based on the origami principle, in which microfiuidic channels were first patterned on a cellulose paper using commercial solid-state wax printer. Hollow-channels were created by laser cutting method as the role of both injecting ending and reaction tank. After screen printing three elec- trodes system, the resulting planar paper sheets were then folded into steric structures and functional- ized by in-situ synthesized reduced graphene oxide. As a proof-of-concept, such lab-on-paper device was employed in the ratiometric electrochemical monitoring of zinc ion from the environment and HepG2 cells extract, by combining with co-catalysis of porous metal-organic frameworks and hemin/ G-quadruplex toward H202 in the linear range of 0.1-7,000 nmol/L. The results indicated that integrating hollow-channel with steric lab-on-paper offered a new methodological approach for the development of metal ions monitoring research. It is believed that it could be useful for various point-of-care related research fields, such as, on-site environmental monitoring, food safety, and disease diagnosis.

A Paper-Supported Photoelectrochemical Sensing Platform Based on Surface Plasmon Resonance Enhancement for Real-Time H_(2)S Determination

Based on in situ generation of CdS quantum dots(QDs)and surface plasmon resonance(SPR)enhancement between CdS QDs and Ag nanoparticles(NPs),an innovative paper-supported photoelectrochemical(PEC)sensing platform was constructed for real-time intracellular H_(2)S detection.SiO_(2)shell was coated on the Ag NPs to improve the stability of Ag NPs.H_(2)S was used to trigger the formation of CdS QDs,thereby inducing an improvement of photocurrent response.CdS QDs grown on the Ag@SiO_(2)core-shell NPs worked efficiently to absorb visible light.The resulting CdS QDs-Ag@SiO_(2)core-shell NPs exhibit improved PEC behavior,which was attributed to the surface plasmon-resonance effect of Ag NPs.Meanwhile,the separation of cell binding from the photoelectrode would eliminate the commonly existing affection dur-ing the biorecognition processes.This novel SPR-enhanced PEC sensing platform not only achieved satisfactory analysis results toward H_(2)S,but also showed excellent sensitivity,selectivity,low cost,and portable features.The strategy of the SPR through the in situ generation of semiconductor nanoparticles on the surface of noble metal semiconductor paves way for the improvements of PEC analytical performance.