Mesoporous Nickel Oxide (NiO) Nanopetals for Ultrasensitive Glucose Sensing

A Redox Mediator-Free Highly Selective and Sensitive Electrochemical Aptasensor for Patulin Mycotoxin Detection in Apple Juice Using Ni-NiO Pseudocapacitive Nanomaterials

Pseudocapacitive nanomaterials have recently gained significant attention in electrochemical biosensors due to their rapid response, long cycle life, high surface area, biomolecule compatibility, and superior energy storage capabilities. In our study, we introduce the potential of using Ni-NiO nanofilm's pseudocapacitive traits as transducer signals in electrochemical aptasensors. Capitalizing on the innate affinity between histidine and nickel, we immobilized histidine-tagged streptavidin (HTS) onto Ni-NiO-modified electrodes. Additionally, we employed a biolayer interferometry-based SELEX to generate biotinylated patulin aptamers. These aptamers, when placed on Ni-NiO-HTS surfaces, make a suitable biosensing platform for rapid patulin mycotoxin detection in apple juice using electrochemical amperometry in microseconds. The novelty lies in optimizing pseudocapacitive nanomaterials structurally and electrochemically, offering the potential for redox mediator-free electrochemical aptasensors. Proof-of-concept is conducted by applying this surface for the ultrasensitive detection of a model analyte, patulin mycotoxin. The aptamer-functionalized bioelectrode showed an excellent linear response (10-106 fg/mL) and an impressive detection limit (1.65 fg/mL, +3σ of blank signal). Furthermore, reproducibility tests yielded a low relative standard deviation of 0.51%, indicating the good performance of the developed biosensor. Real sample analysis in freshly prepared apple juice revealed no significant difference (P < 0.05) in current intensity between spiked and real samples. The sensor interface maintained excellent stability for up to 2 weeks (signal retention 96.45%). The excellent selectivity, stability, and sensitivity of the electrochemical aptasensor exemplify the potential for using nickel-based pseudocapacitive nanomaterials for a wide variety of electrochemical sensing applications.

Nature-inspired functional porous materials for low-concentration biomarker detection

Nanostructuration is a promising tool for enhancing the performance of sensors based on electrochemical transduction. Nanostructured materials allow for increasing the surface area of the electrode and improving the limit of detection (LOD). In this regard, inverse opals possess ideal features to be used as substrates for developing sensors, thanks to their homogeneous, interconnected pore structure and the possibility to functionalize their surface. However, overcoming the insulating nature of conventional silica inverse opals fabricated via sol-gel processes is a key challenge for their application as electrode materials. In this work, colloidal assembly, atomic layer deposition and selective surface functionalization are combined to design conductive inverse opals as an electrode material for novel glucose sensing platforms. An insulating inverse opal scaffold is coated with uniform layers of conducting aluminum zinc oxide and platinum, and subsequently functionalized with glucose oxidase embedded in a polypyrrole layer. The final device can sense glucose at concentrations in the nanomolar range and is not affected by the presence of common interferents gluconolactone and pyruvate. This method may also be applied to different conductive materials and enzymes to generate a new class of highly efficient biosensors.

Sensitive Electrochemical Non-Enzymatic Detection of Glucose Based on Wireless Data Transmission

Miniaturization and wireless continuous glucose monitoring are key factors for the successful management of diabetes. Electrochemical sensors are very versatile and can be easily miniaturized for wireless glucose monitoring. The authors report a microneedle-based enzyme-free electrochemical wireless sensor for painless and continuous glucose monitoring. The microneedles (MNs) fabricated consist of a 3 × 5 sharp and stainless-steel electrode array configuration. Each MN in the 3 × 5 array has 575 µm × 150 µm in height and width, respectively. A glucose-catalyzing layer, porous platinum black, was electrochemically deposited on the tips of the MNs by applying a fixed cathodic current of 2.5 mA cm⁻² for a period of 200 s. For the non-interference glucose sensing, the platinum (Pt)-black-coated MN was carefully packaged into a biocompatible ionomer, nafion. The surface morphologies of the bare and modified MNs were studied using field-emission scanning electron microscopy (FESEM) and energy-dispersive X-ray analysis (EDX). The wireless glucose sensor displayed a broad linear range of glucose (1→30 mM), a good sensitivity and higher detection limit of 145.33 μA mM⁻¹ cm⁻² and 480 μM, respectively, with bare AuMN as a counter electrode. However, the wireless device showed an improved sensitivity and enhanced detection limit of 445.75, 165.83 μA mM⁻¹ cm⁻² and 268 μM, respectively, with the Pt-black-modified MN as a counter electrode. The sensor also exhibited a very good response time (2 s) and a limited interference effect on the detection of glucose in the presence of other electroactive oxidizing species, indicating a very fast and interference-free chronoamperometric response.

Sensitive Electrochemical Detection of Bioactive Molecules (Hydrogen Peroxide, Glucose, Dopamine) with Perovskites-Based Sensors

Perovskite-modified electrodes have received increasing attention in the last decade, due to their electrocatalytic properties to undergo the sensitive and selective detection of bioactive molecules, such as hydrogen peroxide, glucose, and dopamine. In this review paper, different types of perovskites involved for their electrocatalytic properties are described, and the proposed mechanism of detection is presented. The analytical performances obtained for different electroactive molecules are listed and compared with those in terms of the type of perovskite used, its nanostructuration, and its association with other conductive nanomaterials. The analytical performance obtained with perovskites is shown to be better than those of Ni and Co oxide-based electrochemical sensors. Main trends and future challenges for enlarging and improving the use of perovskite-based electrochemical sensors are then discussed.

Amorphous Ni-P nanoparticles anchoring on nickel foam as an efficient integrated anode for glucose sensing and oxygen evolution

Ever-growing efforts have been devoted to developing cost-effective and earth-abundant electrocatalysts with high-performance in biosensing and energy energy conversion. In this work, amorphous nickel-phosphorus (Ni-P) nanoparticles anchoring on Ni foam (Ni-P/NF) were prepared through a facile electroless deposition approach. The morphology and composition were characterized by scanning electron microscopy, x-ray diffraction and x-ray photoelectron spectroscopy. As an integrated anode, Ni-P/NF exhibits high performance towards glucose electrochemical sensing, with a high sensitivity of 13.89 mA mM^-1 cm^-2, a low detection limit of 1 µM, a wide detection ranges from 2 µM to 0.54 mM, and a quick response (<10 s), as well as good selectivity and reliability for real sample analysis in human serum. In addition to electrocatalytic glucose oxidation, Ni-P/NF shows remarkable catalytic activity towards oxygen evolution reaction (OER) in alkaline solution and it only needs an overpotential of 360 mV to afford 50 mA cm^-2. Moreover, Ni-P/NF shows excellent durability under alkaline OER condition. All these results demonstrate Ni-P/NF as highly efficient integrated anode in both biosensing and energy conversion.

Mesoporous nickel oxide nanostructures: influences of crystalline defects and morphological features on mediator-free electrochemical monosaccharide sensor application

Morphological and surface features are the key tools used to tune the catalytic performance of any metal oxide. In the present study, nickel oxide nanoparticles (NiO NPs) with three different morphologies were prepared using a simple hydrothermal method. The electrocatalytic performance of the prepared NiO NPs was evaluated with regard to the detection of monosaccharide glucose. The physicochemical properties of prepared NiO nanostructures were confirmed using different conventional characterization techniques. The flower-like morphological NiO NPs with nanosized petals have a high surface area and a more defective surface, resulting in improved heterogeneous catalytic activity compared to hexagonal and spherical morphological NiO NPs in glucose oxidation. The anionic and cationic vacancies on the mesoporous surface of NiO nanopetals endorsed an enhanced charge transfer efficiency compared to other NiO morphologies. The effect of scan rate, confirmed by cyclic voltammetry analysis, ensured the diffusion-controlled quasi-reversible electrochemical reaction between surface-modified electrodes and analyte. The NiO petals showed a wide linear detection range (100 nmol L^-1-12 mmol L^-1) and a lower detection limit of 57 nmol L^-1. In addition, the anti-interference ability, repeatability, stability and real sample analysis further affirmed the enhanced catalytic features of NiO nanopetals. The results showed that defective surfaces and surface features of the NiO nanostructures could be used to tune their overall sensor performance in future applications.

Electrodeposition of nickel nanostructures using silica nanochannels as confinement for low-fouling enzyme-free glucose detection

This work reports an enzyme-free glucose sensor based on nickel nanostructures electrodeposited on a fluorine-doped tin oxide (FTO) electrode modified with a silica nanochannel membrane (SNM).

Evaluation of some biological, biochemical, and hematological aspects in male albino rats after acute exposure to the nano-structured oxides of nickel and cobalt

Nanomaterial applications are a fast-developing field. In spite of their powerful advantages, many open questions regarding how these small-sized chemicals may influence the environment and human health. However, scarce reports are available on the potential hazards of combined nanoparticles, taken into consideration that nickel oxide (NiO) and cobalt (II, III) oxide (Co₃O₄) nanoparticles (NPs) are already used together in many applications. Hence, the present work was designed to study the probable changes in some biological, hematological, and serum biochemical variables throughout 2 weeks following an oral administration of 0.5 g and 1.0 g of NiO-NPs or/and Co₃O₄-NPs per kilogram body weight of rats. As compared with the controls, the exposure to NiO-NPs or Co₃O₄-NPs solely caused significant elevations in the relative weights of brain (RBW), kidney (RKW) and liver (RLW), water consumption (WC), red blood cells (RBCs) count, hemoglobin (Hb) content, packed cell volume (PCV), and serum levels of low-density lipoprotein cholesterol (LDL-C), glucose, creatinine, urea, and uric acid as well as serum activities of aspartate and alanine aminotransferases (ASAT and ALAT). In addition, remarkable declines in the total body weight (TBW), feed consumption (FC), white blood cells (WBCs) count, serum levels of total protein (TP), albumin, albumin/globulin ratio, total cholesterol (TC), triglycerides (TG), and high-density lipoprotein cholesterol (HDL-C) were caused by administration of NiO-NPs or Co₃O₄-NPs, separately. On contrary, the co-administration of NiO-NPs and Co₃O₄-NPs together caused less noticeable changes in most of studied variables as compared with those administered NiO-NPs or Co₃O₄-NPs, individually. In conclusion, the exposure to a combination of NiO-NPs and Co₃O₄-NPs suppressed the adverse effects of the individual NPs on the studied variables.

Porous carbon-NiO nanocomposites for amperometric detection of hydrazine and hydrogen peroxide

A hydrothermal route is reported for the preparation of a composite consisting of sheet-like glucose-derived carbon and nickel oxide nanoparticles. The nanocomposites were prepared at different annealing temperatures and exploited as electrode materials for amperometric (i-t) determination of hydrazine (N₂H₄) and hydrogen peroxide (H₂O₂) at trace levels. The performances of the sensors were assessed by cyclic voltammetry and amperometry detection using a rotating disk electrode (RDE) technique. The modified electrode annealed at ca. 300 °C was found to exhibit the best electrocatalytic performance in terms of sensitive and selective detection of N₂H₄ and H₂O₂ even in the presence of interfering species. The electrode is inexpensive, robust, easy to prepare in large batches, highly stable, and has a low overpotential. H₂O₂ can be sensed, best at a working voltage of typically 0.13 V vs Ag/AgCl; rotationg speed 1200 rpm) over a wide concentration range (0.01 to 3.9 µM) with a detection limit of 1.5 nM. N₂H₄ can be sensed, best at a working voltage of typically 0.0 V within the concentration range from 0.5 μM to 12 mM with an excellent detection limit of 1.5 µM. Thus, this cost-effective and robust modified electrode, which may be readily prepared in large batch quantity, represents a practical platform for industrial sensing. Graphical abstract Schematic of the hydrothermal method for synthesis of carbon and nickel oxide nanoparticle composites (GCD/NiO-150, GCD/NiO-300, and GCD/NiO-450). The composite was used for the electro-oxidation of hydrazine (N₂H₄) and hydrogen peroxide (H₂O₂) by cyclic voltammetry and amperometry (i-t).

Electrically-Transduced Chemical Sensors Based on Two-Dimensional Nanomaterials

Electrically-transduced sensors, with their simplicity and compatibility with standard electronic technologies, produce signals that can be efficiently acquired, processed, stored, and analyzed. Two dimensional (2D) nanomaterials, including graphene, phosphorene (BP), transition metal dichalcogenides (TMDCs), and others, have proven to be attractive for the fabrication of high-performance electrically-transduced chemical sensors due to their remarkable electronic and physical properties originating from their 2D structure. This review highlights the advances in electrically-transduced chemical sensing that rely on 2D materials. The structural components of such sensors are described, and the underlying operating principles for different types of architectures are discussed. The structural features, electronic properties, and surface chemistry of 2D nanostructures that dictate their sensing performance are reviewed. Key advances in the application of 2D materials, from both a historical and analytical perspective, are summarized for four different groups of analytes: gases, volatile compounds, ions, and biomolecules. The sensing performance is discussed in the context of the molecular design, structure-property relationships, and device fabrication technology. The outlook of challenges and opportunities for 2D nanomaterials for the future development of electrically-transduced sensors is also presented.