Facile hydrothermal synthesis of manganese sulfide nanoelectrocatalyst for high sensitive detection of Bisphenol A in food and eco-samples.

Bisphenol A (BPA) is a renowned plasticizer, and a key component of various plastics, resins, and food packaging materials. However, BPA have been identified as an endocrine disruption compound and cause severe consequences such as infertility, diabetic, obesity, carcinoma, and possess high risk of exposure in aquatic ecosystem. To this, we crafted an ultrasensitive electrochemical sensor based on the manganese sulfide nanoparticles (MnS NPs) catalyzed electrochemical oxidation of BPA, and its eventual application in rapid screening of BPA contamination. The physiochemical characteristics and electrocatalytic performance of the MnS nanocatalyst have been well studied and utilized in the fabrication of MnS/GCE based BPA sensor. The fabricated BPA sensor has shown a broad dynamic range (20 nM-2.15 mM), lower detection limits (6.52 nM) and promising towards rapid screening of BPA contaminations in food and environmental samples under mimicked real-world conditions with excellent accuracy and precision.

3D Flower-like NiCo Layered Double Hydroxides: An Efficient Electrocatalyst for Non-Enzymatic Electrochemical Biosensing of Hydrogen Peroxide in Live Cells and Glucose in Biofluids.

Herein, a hierarchical structure of flower-like NiCo layered double hydroxides (NiCo LDH) microspheres composed of three-dimensional (3D) ultrathin nanosheets was successfully synthesized via a facile hydrothermal approach. The formation of NiCo LDH was confirmed by various physicochemical studies, and the NiCo LDH-modified glassy carbon electrode was used as an efficient dual-functional electrocatalyst for non-enzymatic glucose and hydrogen peroxide (H2O2) biosensor. The host matrix of hydrotalcite NiCo LDH exhibits the enhanced electrocatalytic sensing performances with a quick response time (<3 s), wide linear range (50 nM-18.95 mM and 20 nM-11.5 mM) and lowest detection limits (S/N = 3) (10.6 and 4.4 nM) toward glucose and H2O2, and also it exhibits good stability, selectivity, and reproducibility. In addition, this biosensor was successfully utilized to the real-time detection of endogenous H2O2 produced from live cells and glucose in various biological fluids, and demonstrates that the as synthesized NiCo LDH may provide a successful pathway for physiological and clinical pathological diagnosis.

FeMn layered double hydroxides: an efficient bifunctional electrocatalyst for real-time tracking of cysteine in whole blood and dopamine in biological samples.

A peculiar clock-regulated design of FeMn-LDHs (FMH) with specific physiochemical attributes has been developed and used for highly sensitive detection of cysteine (CySH) and dopamine (DA). The FMH nanoparticles were synthesized via a facile hydrothermal approach clocked at various (6 h, 12 h and 18 h) operating periods. Under optimal conditions, FMH were obtained in three unique morphologies such as hexagonal plate like, cubic, and spherical structures corresponding to the clocked periods of 6 h, 12 h, and 18 h, respectively. Among these, FMH-12 h possess the minimal particle size (54.45 nm), a large surface area (7.60 m2 g-1) and the highest pore diameter (d = 4.614 nm). In addition to these superior physiochemical attributes, the FMH nanocubes exhibit excellent electrochemical behaviors with the lowest charge transfer resistance (Rct; 96 Ω), a high heterogeneous rate constant (7.81 × 10-6 cm s-1) and a good electroactive surface area (0.3613 cm2), among the three. The electrochemical biosensor based on the FMH nanocubes exhibits a remarkable catalytic activity toward CySH and DA with a low detection limit (9.6 nM and 5.3 nM) and a broad linear range (30 nM-6.67 mM and 20 nM-700 µM). The FMH based biosensor is also feasible for the real-world detection of CySH in whole blood and DA in biological fluids with satisfactory results. The proposed sensor possessed high selectivity, good repeatability, and reproducibility toward CySH and DA sensing.

Enzyme-free electrocatalytic sensing of hydrogen peroxide using a glassy carbon electrode modified with cobalt nanoparticle-decorated tungsten carbide.

An efficient non-enzymatic electrochemical sensor for hydrogen peroxide (H2O2) was constructed by modifying a glassy carbon electrode (GCE) with a nanocomposite prepared from cobalt nanoparticle (CoNP) and tungsten carbide (WC). The nanocomposite was prepared at low temperature through a simple technique. Its crystal structure, surface morphology and elemental composition were investigated via X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The results showed the composite to be uniformly distributed and that the CoNP are well attached to the surface of the flake-like WC. Electrochemical studies show that the modified GCE has an improved electrocatalytic activity toward the reduction of H2O2. H2O2 can be selectively detected, best at a working voltage of -0.4 V (vs. Ag/AgCl), with a 6.3 nM detection limit over the wide linear range from 50 nM to 1.0 mM. This surpasses previously reported non-enzymatic H2O2 sensors. The sensor was successfully applied to the determination of H2O2 in contact lens solutions and in spiked serum samples. Graphical abstract Schematic presentation of a method for electrochemical sensing of hydrogen peroxide in real samples using cobalt nanoparticle decorated tungsten carbide (WCC) modified glassy carbon electrode (GCE).

Sonochemical synthesis of molybdenum oxide (MoO3) microspheres anchored graphitic carbon nitride (g-C3N4) ultrathin sheets for enhanced electrochemical sensing of Furazolidone.

Present strategy introduce the sonochemical synthesis of molybdenum oxide (MoO3) microspheres anchored graphitic carbon nitride (g-C3N4) ultrathin sheets as a novel electrocatalyst for the detection of Furazolidone (FU). TEM results revealed that MoO3 are microspheres with an average size of 2 µM and the g-C3N4 seems like ultrathin sheets. Owing to their peculiar morphological structure, g-C3N4/MoO3 composite modified electrode provided an enriched electroactive surface area (0.3788 cm2) and higher heterogeneous electron transfer kinetics (K°eff = 4.91×10-2 cm s-1) than the other controlled electrodes. It is obviously observed from the voltammetric studies that the proposed sensor based on g-C3N4/MoO3 composite can significantly improve the electrocatalytic efficiency towards the sensing of FU. Due to the excellent synergic effect of g-C3N4/MoO3 composite, can detect the ultra-level FU with a limit of detection of 1.4 nM and a broad dynamic range of 0.01-228 µM, which surpassed the many previously reported FU sensors. Hence, the proposed sensor was successfully applied to sensing the FU in human blood serum, urine and pharmaceutical samples, gained an agreeable recoveries.

Ultrasonic energy-assisted preparation of ß-cyclodextrin-carbon nanofiber composite: Application for electrochemical sensing of nitrofurantoin.

A simple ultrasonic energy assisted synthesis of ß-cyclodextrin (ß-CD) supported carbon nanofiber composite (CNF) and its potential application in electrochemical sensing of antibiotic nitrofurantoin (NFT) is reported. The elemental composition and surface morphology of the ß-CD/CNF composite was validated through Field emission scanning electron microscopy, energy dispersive X-ray microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The uniform enfolding of hydrophilic ß-CD over CNF enhance the aqueous dispersion and offer abundant active surface to the ß-CD/CNF composite. Further, the electrocatalytic efficacy of the ß-CD/CNF composite is utilized to fabricate an electrochemical sensor for the high sensitive quantitative detection of NFT. Under optimized analytical conditions, the sensor displays a broad working range of 0.004-308 µM and calculated detection limit of 1.8 nM, respectively. In addition, the sensor showcased a good selectivity, storage, and working stability, with amiable reproducibility. The point-of-care applicability of the sensor was demonstrated with NFT spiked human blood serum and urine sample with reliable analytical performance. The simple, cost-effective NFT sensor based on ß-CD/CNF offered outstanding analytical performance in real-world samples with higher reliability.

Amperometric sensing of nitrite at nanomolar concentrations by using carboxylated multiwalled carbon nanotubes modified with titanium nitride nanoparticles.

A glassy carbon electrode (GCE) was modified with a nanocomposite prepared from carboxylated multiwalled carbon nanotubes (c-MWCNT) and titanium nitride (TiN) nanoparticles to obtain a sensor for nitrite. The nanocomposite was characterized by transmission electron microscopy, elemental mapping, X-ray diffraction, and Raman spectroscopy. Electrochemical studies results show the modified GCE to possess a low electrochemical resistance (Rct = 7 Ω) and a large electroactive surface (A = 0.112 cm2). The heterogeneous electron transfer rate (ks) is found to be 1.26 × 10-2 cm s-1. Due to the excellent synergistic effect of c-MWCNT and TiN, the GCE displays and excellent performance in terms of nitrite sensing. At a typical working voltage of +0.8 V (vs. Ag/AgCl), the limit of detection (LOD) is as low as 4 nM, and the useful analytical range extends from 6 nM to 950 µM. This is much better than the LODs of previously reported nitrite sensors. The sensor is fast (response time 4 s), selective, and long-term stable. It was applied to the determination of nitrite in spiked water and meat samples and gave good recoveries. Graphical abstract Schematic presentation of electrochemical determination of nitrite using carboxylated multiwalled carbon nanotubes modified with titanium nitride nanoparticles modified electrode.

Facile Solvothermal Preparation of Mn2CuO4 Microspheres: Excellent Electrocatalyst for Real-Time Detection of H2O2 Released from Live Cells.

Hydrogen peroxide (H2O2) is an eminent biomarker in pathogenesis; a selective, highly sensitive real-time detection of H2O2 released from live cells has drawn a significant research interest in bioanalytical chemistry. Binary transition-metal oxides (BTMOs) displayed a recognizable benefit in enhancing the sensitivity of H2O2 detection; although the reported BTMO-based H2O2 sensor's detection limit is still insufficient, it is not appropriate for in situ profiling of trace amounts of cellular H2O2. In this paper, we describe an efficient, reliable electrochemical biosensor based on Mn2CuO4 (MCO) microspheres to assay cellular H2O2. The Mn2CuO4 microspheres were prepared through a superficial solvothermal method. It is obvious from impedance studies, introduction of manganese into copper oxide lattice significantly improved the ionic conductivity, which is beneficial for the electrochemical sensing process. Thanks to the distinct microsphere structure and excellent synergy, MCO-modified electrode exhibited excellent nonenzymatic electrochemical behavior toward H2O2 sensing. The MCO-modified electrode delivered a broad working range (36 nM to 9.3 mM) and an appreciable detection limit (13 nM), with high selectivity toward H2O2. To prove its practicality, the developed sensor was applied in the detection of cellular H2O2 released by RAW 264.7 cells in presence of CHAPS. These results label the possible appliance of the sensor in clinical analysis and pathophysiology. Thus, BTMOs are evolving as a promising candidate in designing catalytic matrices for biosensor applications.