Promoted Non-enzymatic Glucose Sensor Based on Synergistic Effect of Hydrothermal Synthesized Ni(OH)_(2)-Graphene Nanocomposite

Although glucose electrochemical sensors based on enzymes play a dominant role in market,their stability remains a problem due to the inherent nature of enzymes.Therefore,glucose sensors that are independent on enzymes have attracted more attention for the development of stable detection devices.Here we present an enzyme-free glucose sensor based on Ni(OH)_(2)and reduced graphene oxide(rGO).The as-fabricated sensor still exhibits excellent electrocatalytic activity for detecting glucose under enzyme independent conditions.The enhanced catalytic performance may due to synergistic effect as follows:(i)the interaction between the Ni2+andπelectron of graphene induces the formation of theβ-phase Ni(OH)_(2)with higher catalytic activity;(ii)the frozen dry process works as a secondary filtration,getting rid of poorly formed Ni(OH)_(2)particles with low catalytic activity;(iii)the rGO network with good conductivity provides a good electronic pathway for promoting electron transfer to reduce the response time.Based on the synergistic effect,the sensor exhibits a wide linear detection range from 0.2µmol/L to 1.0µmol/L and a low detection limit(0.1µmol/L,S/N=3).The excellent detection performance,as well as the easy and low-cost preparation method,suggests the promising applicability of the sensor in the glucose detection market.

Characterizing cellular mechanical phenotypes with mechanonode-pore sensing

The mechanical properties of cells change with their differentiation,chronological age,and malignant progression.Consequently,these properties may be useful label-free biomarkers of various functional or clinically relevant cell states.Here,we demonstrate mechano-node-pore sensing(mechano-NPS),a multi-parametric single-cell-analysis method that utilizes a four-terminal measurement of the current across a microfluidic channel to quantify simultaneously cell diameter,resistance to compressive deformation,transverse deformation under constant strain,and recovery time after deformation.We define a new parameter,the whole-cell deformability index(wCDI),which provides a quantitative mechanical metric of the resistance to compressive deformation that can be used to discriminate among different cell types.The wCDI and the transverse deformation under constant strain show malignant MCF-7 and A549 cell lines are mechanically distinct from non-malignant,MCF-10A and BEAS-2B cell lines,and distinguishes between cells treated or untreated with cytoskeleton-perturbing small molecules.We categorize cell recovery time,ΔT_(r),as instantaneous(ΔTr~0 ms),transient(ΔT_(r)≤40 ms),or prolonged(ΔT_(r)>40 ms),and show that the composition of recovery types,which is a consequence of changes in cytoskeletal organization,correlates with cellular transformation.Through the wCDI and cell-recovery time,mechano-NPS discriminates between sub-lineages of normal primary human mammary epithelial cells with accuracy comparable to flow cytometry,but without antibody labeling.Mechano-NPS identifies mechanical phenotypes that distinguishes lineage,chronological age,and stage of malignant progression in human epithelial cells.

Wide-field optical sizing of single nanoparticles with 10 nm accuracy

There is an increasing demand for new technologies to rapidly measure individual nanoparticles in situ for applications,including early-stage diagnosis of human diseases and environmental monitoring.Here,we demonstrate a label-free wide-field optical microscopy capable of sizing dispersed non-luminescent dielectric nanoparticles(with diameters down to 22 nm)with 10 nm accuracy.This technique utilizes enhanced nanoparticle-perturbed scattering by surface plasmons created on a gold film.In the meantime,an azimuthal rotation illumination module is installed on this microscope and a differential image processing technique is carried out.The relationship between the scattering intensity and the particle size was experimentally measured with good consistency with the theoretical prediction.The capability of precise measurement of the size of dispersed nanoparticles within a larger field of view in a label-free,non-invasive and quantitative manner may find broad applications involving single nanoparticle chemistry and physics.