tA highly sensitive and non-invasive label-free biosensor was demonstrated for glucose detection using(3-aminopropyl)triethoxysilane (APTES) and glucose oxidase (GOx) surface modified polysilicon nanogap(PSNG) lab-on-chip. Fabricated gap size below 100 nm nanogap (NG) was used to discriminate the detec-tion of the prepared dextrose monohydrate (DEX) which used as reference. The results were comparedwith salivary glucose (SAL) samples and an on spot blood glucometer. A simple immobilization step ofAPTES and GOx was demonstrated and the result shows an excellent catalytic activity toward the oxi-dation of glucose with a current sensitivity of 42.08 A mM?1cm?2(or NG conductance sensitivity of165.3 nS cm?1). It was found that the working capability of this enzyme based biosensor was extremelywide linear ranging from 5 M to 50 mM, and the limit of detection (LOD) can be achieved down to0.6 M. Moreover, the amperometric response has affectively distinguished, the sensor response timeof 3 s is achieved. The reproducibility and stability of the enzymatic activity of biosensor were success-fully distinguished for glucose sensing. AC dielectric and impedance spectroscopy measurement alsoshows insignificant effect of polarization which is due to the accumulation of ions (double layers) onthe surface of PSNG electrodes. Therefore, this glucose biosensor could be an attractive candidate for commercialization as a point-of-care clinical diagnostic tool.

Creating novel nanostructures is a primary step for high-performance analytical sensing. Herein, a new worm like nanostructure with Zinc Oxide-gold (ZnO/Au) hybrid was fabricated through an aqueous hydrothermal method, by doping Au-nanoparticle (AuNP) on the growing ZnO lattice. During ZnO growth, fine tuning the solution temperature expedites random curving of ZnO nanorods and forms nano-worms. The nano-worms which were evidenced by morphological, physical and structural analyses, revealed elongated structures protruding from the surface (length: 1 µm; diameter: ~100 nm). The appropriate peaks for the face centred cubic gold were (111) and (200), as seen from X-ray diffractogram. The strong interrelation between Au and ZnO was manifested by X-ray photoelectron spectroscopy. The combined surface area increment from the nanoparticle radii and ZnO nanorod random curving gives raise an enhancement in detection sensitivity by increasing bio-loading. ‘Au-decorated hybrid nano-worm’ was immobilized with a probe DNA from Vibrio Cholera and duplexed with a target which was revealed by Fourier Transform Infrared Spectroscopy. Our novel Au-decorated hybrid nano-worm is suitable for high-performance bio-sensing, as evidenced by impedance spectroscopy, having higher-specificity and attained femtomolar (10 fM) sensitivity. Further, higher stability, reproducibility and regeneration on this sensing surface were demonstrated.

Rationally designed biosensing system supports multiplex analyses is warranted for medical diagnosis to determine the level of analyte interaction. The chemically functionalized novel multi-electrode polysilicon nanogap (PSNG) lab-on-chip is designed in this study, facilitates multiplex analyses for a single analyte. On the fabricated 69 nm PSNG, biocompatibility and structural characteristics were verified for the efficient binding of Human Chorionic Gonadotropin (hCG). With the assistance of microfluidics, hCG sample was delivered via single-injection to 3-Aminopropyl(triethoxy)silane (APTES) and Glycidoxypropyl(trimethoxy)silane (GPMS) modified PSNG electrodes and the transduced signal was used to investigate the dielectric mechanisms for multiplex analyses. The results from amperometric response and impedance measurement delivered the scale of interaction between anti-hCG antibody and hCG that exhibited 6.5 times higher sensitivity for the chemical linker, APTES than GPMS. Under optimized experimental conditions, APTES and GPMS modified immunosensor has a limit of detection as 0.56 mIU/ml and 2.93 mIU/ml (at S/N=3), with dissociation constants (Kd) of 5.65±2.5 mIU/ml and 7.28±2.6 mIU/ml, respectively. These results suggest that multiplex analysis of single target could enhance the accuracy of detection and reliable for real-time comparative analyses. The designed PSNG is simple, feasible, requires low sample consumption and could be applied for any given multiplex analyses.