Flexible Electrochemical Transducer Platform for Neurotransmitters

"Nano": An Emerging Avenue in Electrochemical Detection of Neurotransmitters

The growing importance of nanomaterials toward the detection of neurotransmitter molecules has been chronicled in this review. Neurotransmitters (NTs) are chemicals that serve as messengers in synaptic transmission and are key players in brain functions. Abnormal levels of NTs are associated with numerous psychotic and neurodegenerative diseases. Therefore, their sensitive and robust detection is of great significance in clinical diagnostics. For more than three decades, electrochemical sensors have made a mark toward clinical detection of NTs. The superiority of these electrochemical sensors lies in their ability to enable sensitive, simple, rapid, and selective determination of analyte molecules while remaining relatively inexpensive. Additionally, these sensors are capable of being integrated in robust, portable, and miniaturized devices to establish point-of-care diagnostic platforms. Nanomaterials have emerged as promising materials with significant implications for electrochemical sensing due to their inherent capability to achieve high surface coverage, superior sensitivity, and rapid response in addition to simple device architecture and miniaturization. Considering the enormous significance of the levels of NTs in biological systems and the advances in sensing ushered in with the integration of nanotechnology in electrochemistry, the analysis of NTs by employing nanomaterials as interface materials in various matrices has emerged as an active area of research. This review explores the advancements made in the field of electrochemical sensors for the sensitive and selective determination of NTs which have been described in the past two decades with a distinctive focus on extremely innovative attributes introduced by nanotechnology.

Nanosheet composed of gold nanoparticle/graphene/epoxy resin based on ultrasonic fabrication for flexible dopamine biosensor using surface-enhanced Raman spectroscopy

Construction of a fast, easy and sensitive neurotransmitters-based sensor could provide a promising way for the diagnosis of neurological diseases, leading to the discovery of more effective treatment methods. The current work is directed to develop for the first time a flexible Surface-Enhanced Raman Spectroscopy (SERS) based neurotransmitters sensor by using the ultrasonic-assisted fabrication of a new set of epoxy resin (EPR) nanocomposites based on graphene nanosheets (GNS) using the casting technique. The perspicuous epoxy resin was reinforced by the variable loading of GNS giving the general formula GNS/EPR1-5. The designed products have been fabricated in situ while the perspicuous epoxy resin was formed. The expected nanocomposites have been fabricated using 3%, 5%, 10%, 15% and 20% GNS loading was applied for such fabrication process. The chemical, physical and morphological properties of the prepared nanocomposites were investigated by using Fourier transforms infrared spectroscopy, X-ray diffraction, Thermogravimetric analysis, Differential Thermal gravimetry, and field emission scanning electron microscopy methods. The GNS/EPR1-5 nanocomposites were decorated with a layer of gold nanoparticles (Au NPs/GNS/EPR) to create surface-enhanced Raman scattering hot points. The wettability of the Au NPs/GNS/EPR was investigated in comparison with the different nanocomposites and the bare epoxy. Au NPs/GNS/EPR was used as a SERS-active surface for detecting different concentrations of dopamine with a limit of detection of 3.3 µM. Our sensor showed the capability to detect low concentrations of dopamine either in a buffer system or in human serum as a real sample.

Nanowires of polyaniline festooned silver coated paper electrodes for efficient solid-state symmetrical supercapacitors

This paper demonstrates a facile strategy for the development of nanosilver decorated polyaniline coated (PAg) paper-based electrodes for the fabrication of solid-state symmetrical supercapacitors. PAg based printing paper was developed through a two-step process involving initial silver nucleation and growth on the paper followed by aniline polymerization. The developed electrically conductive paper exhibited a highly porous structure and excellent mechanical stability. Further symmetrical supercapacitors having the configuration PAg/electrolyte/PAg were fabricated and evaluated for electrochemical performance such as specific capacitance (483 F g-1 and 613 F g-1 in aqueous 1 M H2SO4 and PVA-H2SO4 gel electrolytes respectively), energy density (69.56 and 85.13 W h kg-1), and power density (243.44 and 405.375 W kg-1) and cycling stability (90% of its capacitance retention even after 2000 cycles), exhibiting excellent performance under various bending conditions. All these exciting results suggest that the developed paper-based flexible solid-state energy device can serve as an efficient, sustainable, and low-cost energy storage system for portable microelectronic devices which are expected to revolutionize the perception of energy-storage devices in the electronics industry.