Electrochemical detection of acute renal disease biomarker by Galinstan nanoparticles interfaced to bilayer polymeric structured dirhenium heptoxide film.

This work describes a facile fabrication of an efficient electrochemical sensor utilizing sonication-derived Galinstan nanoparticles (Galinstan NPs) interfaced to annealed dirhenium heptoxide (Re2O7) thin-film on Silicon (Si) for the quantitative detection of the most promising acute renal disease biomarker Neutrophil Gelatinase Associated Lipocalin (NGAL). Under optimized preconditions, the anti-NGAL antibodies were immobilized on the Galinstan NPs/Re2O7/Si electrode by carbodiimide crosslinking to detect NGAL. The composition, morphology, and structural properties of the electrode were elucidated by various physical characterizations. The sensor obtained a high sensitivity (0.018 µA-1ng-1ml-1, R2 = 0.99) in differential pulse voltammetry and a minimum detection limit (2.14 ng ml-1) in electrochemical impedance spectroscopy for a wide range of NGAL concentrations (25-650 ng ml-1) with high selectivity and stability. The intensified performance of the sensor was achieved by the summed-up electron transfer from the Re2O7 film to Galinstan NPs and Galinstan NPs to the electroactive reactants. Additionally, the outer 2D gallium oxide (Ga2O3) layer of Galinstan Nps enhanced the redox activities, whereas the metallic core contributed to the magnificent conductivity. The excellent recovery rates of the sensor for different concentrations of NGAL measured in commercial human serum by the standard addition method assured the feasibility of the sensor.

Excellent physicochemical and sensing characteristics of a Re x O y based pH sensor at low post-deposition annealing temperature.

pH monitoring in clinical assessment is pivotal as pH imbalance significantly influences the physiological and extracellular functions of the human body. Metal oxide based pH sensors, a promising alternative to bulky pH electrodes, mostly require complex fabrication, high-temperature post-deposition treatment, and high expenses that inhibit their practical applicability. So, there is still room to develop a straightforward and cost-effective metal oxide based pH sensor comprising high sensitivity and reliability. In this report, a novel solution-processed and low-temperature annealed (220 °C) mixed-valence (vii/vi) oxide of rhenium (Re x O y ) was applied in an electrolyte-insulator-semiconductor (EIS) structure. The annealing effect on morphological, structural, and compositional properties was scrutinized by physical and chemical characterizations. The post-annealed Re x O y exhibited a high pH sensitivity (57.3 mV pH-1, R 2 = 0.99), a lower hysteresis (4.7 mV), and a reduced drift rate (1.7 mV h-1) compared to the as-prepared sample for an analytically acceptable pH range (2-12) along with good stability and reproducibility. The magnified sensing performance originated due to the valence state of Re from Re6+ to Re7+ attributed to each electron transfer for a single H+ ion. The device showed high selectivity for H+ ions, which was confirmed by the interference study with other relevant ions. The feasibility of the sensor was verified by measuring the device in real samples. Hence, the ease-of-fabrication and notable sensing performance of the proposed sensor endorsed its implementation for diagnosing pH-related diseases.

Highly sensitive and selective electrochemical detection of lipocalin 2 by NiO nanoparticles/perovskite CeCuOx based immunosensor to diagnose renal failure.

The early detection of lipocalin 2 (LCN 2), a biomarker to diagnose acute kidney injury (AKI) and its consequences leading to renal failure, is highly challenging due to the lack of proper investigating tools. To overcome this issue, we developed nickel oxide nanoparticles modified cerium copper oxide (NiO Nps/CeCuOx) thin film-based immunosensor to determine the presence of LCN 2 in the analyte. The sol-gel deposited CeCuOx (on a silicon (Si) substrate) was post-annealed at different temperatures (700 °C, 800 °C, and 900 °C), where 800 °C showed the optimum electrochemical performance. NiO nanoparticles, prepared by co-precipitation method, were coated on the pre-silanized CeCuOx to obtain the NiO Nps/CeCuOx/Si electrode. The fast electron transfer, excellent redox property, and high surface-to-volume ratio of NiO Nps/CeCuOx based sensing electrode facilitate the successful immobilization of anti-LCN2 by carbodiimide coupling. The structural, compositional, and stoichiometric properties of the electrode were evaluated by X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and ultraviolet-visible spectroscopy. The immunosensor achieved a significantly low limit of detection (LOD) of 4.23 ng ml-1 for an acceptable linear range of 25-400 ng ml-1 in voltammetric measurement. The device showed high selectivity compared to other related biomolecules. The excellent recovery rates in human serum spiked with LCN2 confirmed the feasibility of the biosensor to use in the actual clinical samples. Therefore, the NiO Nps/CeCuOx/Si based LCN2 immunosensor paves a new route to diagnose kidney-related end-stage diseases.

ZIF-8 Nanoparticles Based Electrochemical Sensor for Non-Enzymatic Creatinine Detection.

There is a consistent demand for developing highly sensitive, stable, cost-effective, and easy-to-fabricate creatinine sensors as creatinine is a reliable indicator of kidney and muscle-related disorders. Herein, we reported a highly sensitive and selective non-enzymatic electrochemical creatinine sensor via modifying poly(3,4 ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) coated indium tin oxide (ITO) substrate by zeolitic imidazolate framework-8 nanoparticles (ZIF-8 NPs). The topography, crystallinity, and composition of the sensing electrode were characterized by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The peroxidase-like activity of ZIF-8 nanoparticles enabled it to detect creatinine forming a zinc-creatinine composite. The electrochemical behavior and sensing performance were evaluated by amperometric and impedimetric analysis. The sensor obtained a sufficiently low limit of detection (LOD) of 30 µM in a clinically acceptable linear range (0.05 mM-2.5 mM). The interference study demonstrated high selectivity of the sensor for creatinine concerning other similar biomolecules. The sensing performance of the creatinine sensor was verified in the actual human serum, which showed excellent recovery rates. Hence, the magnificent performance of ZIF-8 based non-enzymatic creatinine sensor validated it as a responsible entity for other complicated renal markers detection.