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This work presents a Chitosan-Graphene Oxide (CS-GO) based array of ultra-thin biosensors with gold (Au) based microgap (60µm) electrode. The cross-linked GO is shown to improve the stability of chitosan substrate in aqueous medium and compatibility with microfabrication steps. The sensor patch has been evaluated for label free monitoring by immobilizing the CS-GO surface with human dermal fibroblast (HDF) cells. The cyclic voltammetry (CV) of HDF cell immobilized CS-GO surface show quasi-reversible nature with characteristic cathodic peak at +300mV and anodic peak at-300mV. Both peaks are stable and repeatable up to 50-scan cycle without any potential shift. The device shows steady state peak enhancement (1.923-11.195nA) during the DHF cell growth period (0-96h). The redox peak enhancement correlates with the cell proliferation rates over time, indicating that it could be employed for investigation of cyto-physiological state against any endo and exogenous stimulation. In addition, the developed sensor-patch was used to detect a wide range of glucose from 1μM to 20mM in vitro with a sensitivity of 0.17µA/mM. Considering these, the presented sensor-patch has a great potential for the detection of glucose level, cell-health proliferation rate at the wound site and diabetic wound monitoring applications.

In this paper, deoxyribonucleic acid functionalized carbon nanotube (DFC) network has been used to develop field effect transistor (FET)-based humidity sensor. The sensor works on the principle of variation of conductance of the DFC network with change in relative humidity. Since the output signal current of the sensor increases exponentially with increase in RH, the device offers higher sensitivity especially at higher RH. The response and recovery times of this zero gate biased FET-based humidity sensor are measured to be 4 and 8 s, respectively, and offers no baseline shift during recovery, which indicates that the sensing mechanism is governed by charge transfer between the DFC and water molecules. The device is highly selective to atmospheric humidity, having no response to nitrogen and oxygen. The effect of temperature on the performance of the sensor is also studied and reported in this paper.

Functionalization of an inorganic nanomaterial like carbon nanotube (CNT) with biological macromolecules like deoxyribonucleic acid (DNA) leads to the formation of hybrid materials with fascinating properties. This article describes the structures of CNT and DNA, portrays the van der Waals force-dominant non-covalent -stacking interactions formed due to their self-assembly, and reviews the electronic, electrochemical, optical, and chemical properties of DNA-functionalized CNTs (DFCs). Current computational developments in simulating and predicting CNT-DNA interactions, alternate functionalization techniques, conformational changes of DNA bases, etc. are discussed. Various characterization techniques using scanning electron microscopy (SEM), scanning tunneling microscopy (STM), atomic force microscopy (AFM), UV-visible, Photoluminescence (PL) and Raman spectroscopy, etc. that help explain DFC properties are detailed. Potential applications for this hybrid material in nanoelectronics and chemical sensors as well as in chirality-based separation of metallic nanotubes from semiconducting ones are considered. The article concludes with current challenges, future directions of research, and prospective applications in this field.

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