Hydrazone chemistry mediated toehold strand displacement cascade and its application for 5-hydroxymethylfurfural analysis.

Hydrazone chemistry has been firstly explored as capturing mode for interface supported toehold strand displacement cascade (TSDC). The method has been further established for analysis of 5-hydroxymethylfurfural (HMF) based on hydrazone chemistry-mediated TSDC. HMF containing aldehyde group can be covalently captured by hydrazine group around magnetic bead through the formation of hydrazone bond, so as to inhibit the immobilization of hybrid duplex and the occurrence of TSDC. Thereby, HMF will cause the change of the fluorescence of modified magnetic bead. With simplicity, specificity, and sensitivity, the method has been successfully applied to analyze HMF in food samples. This paper gives a new insight to explore capturing mode for interface supported TSDC and the established method can be extended for analysis of saccharic derivatives.

Rhodopsin-Like Ionic Gate Fabricated with Graphene Oxide and Isomeric DNA Switch for Efficient Photocontrol of Ion Transport.

Rhodopsin, composed of opsin and isomeric retinal, acts as the primary photoreceptor by converting light into electric signals. Inspired by rhodopsin, we have fabricated a light-regulated ionic gate on the basis of the design of a graphene oxide (GO)-biomimetic DNA-nanochannel architecture. In this design, photoswitchable azobenzene (Azo)-DNA is introduced to the surface of porous anodic alumina (PAA) membrane. With modulation of the interaction between the GO blocker and Azo-DNA via flexibly regulating trans and cis states of Azo under the irradiation of visible and ultraviolet light, alternatively, the ionic gate is switched between ON and OFF states. This newly constructed ionic gate can possess high efficiency for the control of ion transport because of the high blocking property of GO and the rather tiny path within the barrier layer which are both first employed to fabricate ionic gate. We anticipate that this rhodopsin-like ionic gate may provide a new model and method for the investigation of ion channel, ion function, and ion quantity. In addition, because of the advantages of simple fabrication, good biocompatibility, and universality, this bioinspired system may have potential applications as optical sensors, in photoelectric transformation, and in controllable drug delivery.