Gold nanostar and graphitic carbon nitride nanocomposite for serotonin detection in biological fluids and human embryonic kidney cell microenvironment.

A nanosensor comprising of gold nanostars (Au-Nstars)-graphitic carbon nitride (g-C3N4) nanocomposite layered on a glassy carbon electrode (GCE) to detect serotonin (ST) in various body fluids has been fabricated. The nanocomposite and the sensing platform have been thoroughly characterized with UV-visible spectroscopy (UV-vis), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive X-ray photoelectron spectroscopy (EDX), and electrochemical techniques such as cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). The designed ST detection probe has achieved a linear dynamic range (LDR) in the range 5 × 10-7 and 1 × 10-3 M with a limit of detection (LOD) of 15.1 nM (RSD < 3.3%). The ST detection capability of the fabricated sensor ranges between the normal and several abnormal pathophysiological situations. The sensor effectively detects ST in real matrices such as urine and blood serum, thus, showing its direct diagnostic applicability. Additionally, the sensor has been tested in the microenvironment of human embryonic kidney (HEK) cells to assess the possibility of ST secretion in cell lines. Interferences because of co-existing molecules have been evaluated, and the shelf-life of the fabricated sensor has been obtained as 8 weeks.

Applications of Smart Material Sensors and Soft Electronics in Healthcare Wearables for Better User Compliance.

The need for innovation in the healthcare sector is essential to meet the demand of a rapidly growing population and the advent of progressive chronic ailments. Over the last decade, real-time monitoring of health conditions has been prioritized for accurate clinical diagnosis and access to accelerated treatment options. Therefore, the demand for wearable biosensing modules for preventive and monitoring purposes has been increasing over the last decade. Application of machine learning, big data analysis, neural networks, and artificial intelligence for precision and various power-saving approaches are used to increase the reliability and acceptance of smart wearables. However, user compliance and ergonomics are key areas that need focus to make the wearables mainstream. Much can be achieved through the incorporation of smart materials and soft electronics. Though skin-friendly wearable devices have been highlighted recently for their multifunctional abilities, a detailed discussion on the integration of smart materials for higher user compliance is still missing. In this review, we have discussed the principles and applications of sustainable smart material sensors and soft electronics for better ergonomics and increased user compliance in various healthcare devices. Moreover, the importance of nanomaterials and nanotechnology is discussed in the development of smart wearables.

Clinically comparable impedimetric immunosensor for serum alkaline phosphatase detection based on electrochemically engineered Au-nano-Dendroids and graphene oxide nanocomposite.

In this work, we demonstrate label-free electrochemical impedance spectroscopy (EIS) based alkaline phosphatase (ALP) detection using gold nanoparticles (AuNPs), electrochemically engineered Au-nano-Dendroids, and graphene oxide (GO) nanocomposite. These nanomaterials were sequentially deposited on to the screen-printed carbon electrode (SPCE) and antibodies against ALP (anti-ALP) were immobilized using carbodiimide bioconjugation process. The sensor probe has been characterized extensively using TEM, EDX, SAED, XRD, FE-SEM, FTIR, DIC, and electrochemical techniques. The analytical performance of fabricated biosensor has been evaluated using EIS, where linear dynamic range and limit of detection were obtained to be 100-1000 U/L and 9.10 (±0.12) U/L, respectively. The developed biosensor showed high selectivity towards ALP with negligible interference (ksel « 1; n = 3) due to coexisting molecules. The sensor probe has successfully recovered ALP between 108.84% and 172.50% (n = 3) in human serum samples. The sensor has been used to estimate ALP in clinical serum samples, where the level was found to be 83.15 U/L and was comparable with standard technique used in the hospitals. The shelf life, stability, and reproducibility have also been evaluated.

Sputtering enhanced peroxidase like activity of a dendritic nanochip for amperometric determination of hydrogen peroxide in blood samples.

A nonenzymatic electrochemical nanoprobe is described for the fast determination of hydrogen peroxide (H2O2). A sputtered indium tin oxide electrode with a nano-hierarchical 3D gold structure is used. The nanoprobe was characterized by SEM, EDX, TEM, SAED, and electrochemical techniques. Figures of merit include (a) a fast response time (≤ 1.0 s), (b) two linear dynamic ranges that extend from 10-12 M to 10-10 M and from 10-10 M to10-5 M; and (c) a low limit of detection of 9.8 × 10-13 M. The nanoprobe works in the clinical range and was applied for trace analysis of H2O2 in spiked blood samples, and recoveries ranged between 90 and 96%. It has negligible response (p < 0.001, for n = 3) toward glucose, citric acid, ascorbic acid, uric acid, glycine, and alanine. The shelf-lifetime is found to be 12 weeks. Graphical abstract Schematic representation of a dendritic nanochip with peroxidase-like activity. It is made from an indium tin oxide electrode with a nanohierarchical gold structure and was used for amperometric determination of hydrogen peroxide.

Novel electrochemical biosensor for serotonin detection based on gold nanorattles decorated reduced graphene oxide in biological fluids and in vitro model.

Abnormal level of serotonin (ST) in body fluids is related to various clinical conditions including behavioral and psychotic disorders; hence its fast detection in clinically relevant ranges have tremendous importance in medical science. In view of this, we have developed a novel biosensor for ST detection using Au-nanorattles (AuNRTs)- reduced graphene oxide (rGO) nanocomposite coated on to the gold nanoparticles (AuNPs) deposited glassy carbon electrode (GCE). The nanocomposite/sensor probe was characterized using UV-Vis, TEM, SAED, EDX, AFM, and electrochemical techniques including LSV and EIS. Thereafter, the suitability of fabricated GCE/AuNPs/AuNRTs-rGO-Naf sensor probe was applied for ST determination which showed a linear dynamic range (LDR) of 3 × 10-6 - 1 × 10-3 M and the detection limit (DL) of 3.87 (±0.02) ×10-7 (RSD < 4.2%) M, which falls in the ranges of normal as well as various abnormal pathophysiological conditions. The designed sensor is successfully applied to detect ST in various real matrices viz. urine, blood serum, and in vitro model to show its direct clinical/practical applicability. Interferences due to the coexisting molecules were assessed and the long-term stability of the designed sensor was also examined which was found to be 8 weeks.