Pulse electrodeposited nickel-indium tin oxide nanocomposite as an electrocatalyst for non-enzymatic glucose sensing

Current advancements and prospects of enzymatic and non-enzymatic electrochemical glucose sensors

This review discusses the most current developments and future perspectives in enzymatic and non-enzymatic glucose sensors, which have notably evolved over the preceding quadrennial period. Furthermore, a thorough exploration encompassed the sensor's intricate fabrication processes, the diverse range of materials employed, the underlying principles of detection, and an in-depth assessment of the sensors' efficacy in detecting glucose levels within essential bodily fluids such as human blood serums, urine, saliva, and interstitial fluids. It is worth noting that the accurate quantification of glucose concentrations within human blood has been effectively achieved by utilizing classical enzymatic sensors harmoniously integrated with optical and electrochemical transduction mechanisms. Monitoring glucose levels in various mediums has attracted exceptional attention from industrial to academic researchers for diabetes management, food quality control, clinical medicine, and bioprocess inspection. There has been an enormous demand for the creation of novel glucose sensors over the past ten years. Research has primarily concentrated on succeeding biocompatible and enhanced sensing abilities related to the present technologies, offering innovative avenues for more effective glucose sensors. Recent developments in wearable optical and electrochemical sensors with low cost, high stability, point-of-care testing, and online tracking of glucose concentration levels in biological fluids can aid in managing and controlling diabetes globally. New nanomaterials and biomolecules that can be used in electrochemical sensor systems to identify glucose concentration levels are developed thanks to advances in nanoscience and nanotechnology. Both enzymatic and non-enzymatic glucose electrochemical sensors have garnered much interest recently and have made significant strides in detecting glucose levels. In this review, we summarise several categories of non-enzymatic glucose sensor materials, including composites, non-precious transition metals and their metal oxides, hydroxides, precious metals and their alloys, carbon-based materials, conducting polymers, metal-organic framework (MOF)-based electrocatalysts, and wearable device-based glucose sensors deeply.

Amperometric determination of heavy metal using an HRP inhibition biosensor based on ITO nanoparticles-ruthenium (III) hexamine trichloride composite: Central composite design optimization

A novel horseradish peroxidase (HRP) enzyme inhibition biosensor based on indium tin oxide (ITO) nanoparticles, hexaammineruthenium (III) chloride (RUT), and chitosan (CH) modified glassy carbon electrode (GCE) was developed. The biosensor fabrication process was investigated using scanning electron microscopy, energy-dispersive X-ray spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. The amounts of ITO nanoparticles and RUT were optimized using a 2² central composite design for the optimization of electrode composition. The detection limits were determined as 8 nM, 3 nM, and 1 nM for Pb²⁺, Ni²⁺, and Cd²⁺, respectively. The inhibition calibration curves of the biosensor were found to be within the range of 0.009-0.301 µM with a sensitivity of 11.97 µA µM^-1 cm^-2 (0.85 µA µM^-1) for Pb²⁺, 0.011-0.368 µM with a sensitivity of 10.84 µA µM^-1 cm^-2 (0.77 µA µM^-1) for Ni²⁺, and 0.008-0.372 µM with a sensitivity of 10.99 µA µM^-1 cm^-2 (0.78 µA µM^-1) for Cd²⁺. The type of HRP inhibition by Pb²⁺, Ni²⁺ and Cd²⁺ was investigated by the Dixon and Cornish-Bowden plots. The effects of possible interfering species on the biosensor response were examined. The analysis of Pb²⁺, Ni²⁺, and Cd²⁺ in tap water was demonstrated using the HRP/ITO-RUT-CH/GCE with satisfactory experimental results. The proposed method agreed with the atomic absorption spectrometry results.

High-performance non-enzymatic glucose sensor by hierarchical flower-like nickel(II)-based MOF/carbon nanotubes composite

A hierarchical three-dimensional flower-like nickel(II)-terephthalic acid (Ni(TPA)) metal-organic framework (MOF) was synthesized through a simple solvothermal method. Then the single-walled carbon nanotubes (SWCNT) were doped with the synthesized Ni(TPA) MOF by the ultrasonic method to improve the chemical stability and the electrochemical activity of the MOF. To explore the potential application of the nanocomposite, the Ni(TPA)-SWCNT modified glassy carbon electrode was prepared and used as a non-enzymatic electrochemical sensor for glucose. The results show that the nanocomposite demonstrates remarkably higher electrochemical response as well as stronger electrocatalytic activity toward glucose oxidation, in comparison with the single-component of Ni(TPA) and SWCNT. The Ni(TPA)-SWCNT modified electrode exhibits outstanding performance including excellent selectivity, wide linear range from 20 μM to 4.4 mM, low detection limit of 4.6 μM, and fast response (<5 s) for glucose detection. For glucose analysis in real serum samples, the developed sensor reveals a good agreement with the automatic biochemical analyzer, with the deviation rate of 0-6.7% and correlation coefficient (r) of 0.9940 (n = 20, P < 0.0001), indicating high accuracy and great potential of the sensor for practical application in fast analysis of glucose.

Low-cost and facile synthesis of Ni(OH)2/ZnO nanostructures for high-sensitivity glucose detection

An efficient electrode for non-enzymatic glucose detection is produced with low-cost techniques on a Cu wire. ZnO nanorods (NRs) were grown on a Cu wire by chemical bath deposition and were used as the substrate for pulsed electrodeposition of nanostructured Ni(OH)₂ flakes. The effect of the electrodeposition potential on the final morphology and electrochemical behavior of the Ni(OH)₂/ZnO/Cu structures is reported. ZnO NRs resulted to be well dressed by Ni(OH)₂ flakes and were tested as glucose sensing electrodes in 0.1 M NaOH solution, showing high sensitivities (up to 3 mA mM^-1 cm^-2) and long-term stability. The presence of ZnO NRs was shown to improve the performance of the glucose sensor in terms of electrochemical stability over the time and sensitivity compared to Ni(OH)₂/Cu sample. The reported data demonstrate a simple, versatile and low-cost fabrication approach for effective glucose sensing system within a urban mines framework.

A sensitive and disposable electrochemical immunosensor for detection of SOX2, a biomarker of cancer

A novel, sensitive, disposable indium tin oxide (ITO)-based electrochemical immunosensor was developed firstly for simple, rapid determination of Sex-determining region Y-box 2 (SOX2). SOX2 is a cancer biomarker and used for detecting small cell lung cancer, lung adenocarcinoma, squamous cell carcinoma, skin cancer, prostate cancer, and breast cancer. In this study, a disposable ITO thin film based electrode was used as working electrode for biosensing the interaction between SOX2 antigen and anti-SOX2 antibody. In this study, carboxyethylsilanetriol (CTES) was also utilized for electrode modifying so as to obtain self-assembled monolayers. The formed self-assembled monolayers were activated with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)/N-hydroxysuccinimide (NHS) chemistry and they were used as a heterobifunctional crosslinker and activator, respectively. Anti-SOX2 antibody was used as a biorecognition molecule and was covalently immobilized onto the ITO thin film modified with CTES. Immobilization steps were characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The optimum immobilization conditions such as antibody concentration, antibody and antigen incubation times were examined for the best sensitivity of the immunosensor. Under optimal conditions, this immunosensor had a wide linear detection range (25fg/mL-2pg/mL) with a detection limit as low as 7fg/mL SOX2. Furthermore, the developed SOX2 immunosensor had good storage stability (79.36% of initial activity after 9 weeks), repeatability (3.88% of RSD) and reproducibility (4.25% of RSD). Our developed immunosensor has an acceptable performance for detection of SOX2 antigen, exhibits low detection limit, and has selective and reproducible results in immunoreaction analysis.

Ultra-fast and highly sensitive enzyme-free glucose biosensing on a nickel–nickel oxide core–shell electrode

Ultra-fast (∼1 s) and highly sensitive (1889.8 μA mM⁻¹ cm⁻²) enzyme-free glucose biosensing on a unique NiNiO core–shell electrode.

Hierarchical ZnO nanorods/Ni(OH)2 nanoflakes for room-temperature, cheap fabrication of non-enzymatic glucose sensors

Optimization of hierarchical nanostructures composed of Ni(OH)₂ nanoflakes on ZnO nanorods (NRs) for inexpensive amperometric glucose sensing applications.

Recent advances in non-enzymatic electrochemical glucose sensors based on non-precious transition metal materials: opportunities and challenges

We summarize the latest advances of non-enzymatic glucose detection using non-noble transition metal materials, highlighting their opportunities and challenges.