Highly Oriented Nitrogen‐doped Carbon Nanotube Integrated Bimetallic Cobalt Copper Organic Framework for Non‐enzymatic Electrochemical Glucose and Hydrogen Peroxide Sensor

Electrospun Manganese-Based Metal-Organic Frameworks for MnOx Nanostructures Embedded in Carbon Nanofibers as a High-Performance Nonenzymatic Glucose Sensor

Material-specific electrocatalytic activity and electrode design are essential factors in evaluating the performance of electrochemical sensors. Herein, the technique described involves electrospinning manganese-based metal-organic frameworks (Mn-MOFs) to develop MnOx nanostructures embedded in carbon nanofibers. The resulting structure features an electrocatalytic material for an enzyme-free glucose sensor. The elemental composition, morphology, and microstructure of the fabricated electrodes materials were characterized by using energy-dispersive X-ray spectroscopy (EDX), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Cyclic voltammetry (CV) and amperometric i-t (current-time) techniques are characteristically employed to assess the electrochemical performance of materials. The MOF MnOx-CNFs nanostructures significantly improve detection performance for nonenzymatic amperometric glucose sensors, including a broad linear range (0 mM to 9.1 mM), high sensitivity (4080.6 μA mM-1 cm-2), a low detection limit (0.3 μM, S/N = 3), acceptable selectivity, outstanding reproducibility, and stability. The strategy of metal and metal oxide-integrated CNF nanostructures based on MOFs opens interesting possibilities for the development of high-performance electrochemical sensors.

Carbon nanotubes: a powerful bridge for conductivity and flexibility in electrochemical glucose sensors

The utilization of nanomaterials in the biosensor field has garnered substantial attention in recent years. Initially, the emphasis was on enhancing the sensor current rather than material interactions. However, carbon nanotubes (CNTs) have gained prominence in glucose sensors due to their high aspect ratio, remarkable chemical stability, and notable optical and electronic attributes. The diverse nanostructures and metal surface designs of CNTs, coupled with their exceptional physical and chemical properties, have led to diverse applications in electrochemical glucose sensor research. Substantial progress has been achieved, particularly in constructing flexible interfaces based on CNTs. This review focuses on CNT-based sensor design, manufacturing advancements, material synergy effects, and minimally invasive/noninvasive glucose monitoring devices. The review also discusses the trend toward simultaneous detection of multiple markers in glucose sensors and the pivotal role played by CNTs in this trend. Furthermore, the latest applications of CNTs in electrochemical glucose sensors are explored, accompanied by an overview of the current status, challenges, and future prospects of CNT-based sensors and their potential applications.

The Use of Crystalline Carbon-Based Nanomaterials (CBNs) in Various Biomedical Applications

This review study aims to present, in a condensed manner, the significance of the use of crystalline carbon-based nanomaterials in biomedical applications. Crystalline carbon-based nanomaterials, encompassing graphene, graphene oxide, reduced graphene oxide, carbon nanotubes, and graphene quantum dots, have emerged as promising materials for the development of medical devices in various biomedical applications. These materials possess inorganic semiconducting attributes combined with organic π-π stacking features, allowing them to efficiently interact with biomolecules and present enhanced light responses. By harnessing these unique properties, carbon-based nanomaterials offer promising opportunities for future advancements in biomedicine. Recent studies have focused on the development of these nanomaterials for targeted drug delivery, cancer treatment, and biosensors. The conjugation and modification of carbon-based nanomaterials have led to significant advancements in a plethora of therapies and have addressed limitations in preclinical biomedical applications. Furthermore, the wide-ranging therapeutic advantages of carbon nanotubes have been thoroughly examined in the context of biomedical applications.

Recent advances in metal-organic framework/carbon nanotube nanocomposites for developing analytical applications

Nanoscience shows promise for scientific advancement in many sectors, such as biology, energy, materials, environment, and manufacturing. Nanocomposites are mixtures of two or more materials, one of which is nanosized particles. The composites are expected to show combined features resulting in general enhancements in their physical and chemical properties. Metal-organic frameworks (MOFs) are coordination polymers that have attracted attention from researchers in recent years due to their porosity and controllable functionality. Another example of interesting nanomaterials is carbon nanotubes (CNTs) which are also known for their mechanical and thermal properties. Incorporation of both these materials into a nanocomposite has shown an enhancement in properties and conquered challenges in the defects of construction. This mini-review sheds light on the recent synthetic approaches and characterization of MOF-CNT nanocomposites in order to access porous selective nanocomposites that can improve analyte detection in environmental matrixes and biological systems. A summary of the chemical composition of nanocomposites, analytes in the target, and analytical techniques used is provided.

Recent Progress in MOF-Based Electrochemical Sensors for Non-Enzymatic Glucose Detection

In recent years, substantial advancements have been made in the development of enzyme-free glucose sensors utilizing pristine metal-organic frameworks (MOFs) and their combinations. This paper provides a comprehensive exploration of various MOF-based glucose sensors, encompassing monometallic MOF sensors as well as multi-metal MOF combinations. These approaches demonstrate improved glucose detection capabilities, facilitated by the augmented surface area and availability of active sites within the MOF structures. Furthermore, the paper delves into the application of MOF complexes and derivatives in enzyme-free glucose sensing. Derivatives incorporating carbon or metal components, such as carbon cloth synthesis, rGO-MOF composites, and core-shell structures incorporating noble metals, exhibit enhanced electrochemical performance. Additionally, the integration of MOFs with foams or biomolecules, such as porphyrins, enhances the electrocatalytic properties for glucose detection. Finally, this paper concludes with an outlook on the future development prospects of enzyme-free glucose MOF sensors.

Electrochemical-Based Sensing Platforms for Detection of Glucose and H2O2 by Porous Metal-Organic Frameworks: A Review of Status and Prospects

Establishing enzyme-free sensing assays with great selectivity and sensitivity for glucose and H₂O₂ detection has been highly required in biological science. In particular, the exploitation of nanomaterials by using noble metals of high conductivity and surface area has been widely investigated to act as selective catalytic agents for molecular recognition in sensing platforms. Several approaches for a straightforward, speedy, selective, and sensitive recognition of glucose and H₂O₂ were requested. This paper reviews the current progress in electrochemical detection using metal-organic frameworks (MOFs) for H₂O₂ and glucose recognition. We have reviewed the latest electrochemical sensing assays for in-place detection with priorities including straightforward procedure and manipulation, high sensitivity, varied linear range, and economic prospects. The mentioned sensing assays apply electrochemical systems through a rapid detection time that enables real-time recognition. In profitable fields, the obstacles that have been associated with sample preparation and tool expense can be solved by applying these sensing means. Some parameters, including the impedance, intensity, and potential difference measurement methods have permitted low limit of detections (LODs) and noticeable durations in agricultural, water, and foodstuff samples with high levels of glucose and H₂O₂.

2D bimetallic organic framework nanosheets for high-performance wearable power source and real-time monitoring of glucose

Diabetics often prick their fingertips to measure the glucose levels in their blood. However, this traditional method not only causes prolonged pain but also increases the risk of infection. Hence, in this study, a non-invasive flexible glucose biosensor with high sensitivity was fabricated. Specifically, NiCo metal-organic frameworks (NiCo-MOFs) served as the electrode material of a micro-supercapacitor and sensing material of a glucose sensor. The electrochemical tests verified that the prominent sensitivity of the NiCo bimetal product is 1422.2 μA mM^-1 cm^-2. The micro-supercapacitor based on the as-fabricated NiCo-MOFs showed a high energy density of 11.5 mW h cm^-2 at the power density 0.26 mW cm^-2. In addition, the as-designed glucose device exhibited an excellent sensitivity of 0.31 μA μM^-1. Furthermore, a flexible energy storage and glucose detection system was successfully prepared by further integrating the micro-supercapacitor and glucose sensor. The smart detector could accurately and conveniently measure the glucose concentration in sweat in real-time. Therefore, the wearable real-time sensing device displays feasible application for non-invasive glucose monitoring and health management.

Highly efficient Ag doped δ-MnO2 decorated graphene: Comparison and application in electrochemical detection of H2O2

Cytotoxic H₂O₂ is an inevitable part of our life, even during this contemporary pandemic COVID-19. Personal protective equipment of the front line fighter against coronavirus could be sterilized easily by H₂O₂ for reuse. In this study, Ag doped δ-MnO₂ nanorods supported graphene nanocomposite (denoted as Ag@δ-MnO₂/G) was synthesized as a nonenzymatic electrochemical sensor for the sensitive detection of H₂O₂. The ternary nanocomposite has overcome the poor electrical conductivity of δ-MnO₂ and also the severe aggregation of Ag NPs. Furthermore, δ-MnO₂/G provided a rougher surface and large numbers of functional groups for doping more numbers of Ag atoms, which effectively modulate the electronic properties of the nanocomposite. As a result, electroactive surface area and electrical conductivity of Ag@δ-MnO₂/G increased remarkably as well as excellent catalytic activity observed towards H₂O₂ reduction. The modified glassy carbon electrode exhibited fast amperometric response time (<2 s) in H₂O₂ determination. The limit of detection was calculated as 68 nM in the broad linear range (0.005-90.64 mM) with high sensitivity of 104.43 µA mM^-1 cm^-2. No significant interference, long-term stability, excellent reproducibility, satisfactory repeatability, practical applicability towards food samples and wastewater proved the efficiency of the proposed sensor.

Metal–Organic Frameworks for Electrocatalytic Sensing of Hydrogen Peroxide

The electrochemical detection of hydrogen peroxide (H₂O₂) has become more and more important in industrial production, daily life, biological process, green energy chemistry, and other fields (especially for the detection of low concentration of H₂O_2). Metal organic frameworks (MOFs) are promising candidates to replace the established H₂O₂ sensors based on precious metals or enzymes. This review summarizes recent advances in MOF-based H₂O₂ electrochemical sensors, including conductive MOFs, MOFs with chemical modifications, MOFs-composites, and MOF derivatives. Finally, the challenges and prospects for the optimization and design of H₂O₂ electrochemical sensors with ultra-low detection limit and long-life are presented.

Cu(ii)-assisted self-assembly of dicyandiamide-derived carbon dots: construction inspired from chemical evolution and its H2O2 sensing application

In the rapid development of artificial nanomaterials comparable to biological enzymes, we propose herein a novel concept for the construction of functional materials inspired from chemical evolution.

Bimetallic Nanomaterials-Based Electrochemical Biosensor Platforms for Clinical Applications

Diabetes is a foremost health issue that results in ~4 million deaths every year and ~170 million people suffering globally. Though there is no treatment for diabetes yet, the blood glucose level of diabetic patients should be checked closely to avoid further problems. Screening glucose in blood has become a vital requirement, and thus the fabrication of advanced and sensitive blood sugar detection methodologies for clinical analysis and individual care. Bimetallic nanoparticles (BMNPs) are nanosized structures that are of rising interest in many clinical applications. Although their fabrication shares characteristics with physicochemical methodologies for the synthesis of corresponding mono-metallic counterparts, they can display several interesting new properties and applications as a significance of the synergetic effect between their two components. These applications can be as diverse as clinical diagnostics, anti-bacterial/anti-cancer treatments or biological imaging analyses, and drug delivery. However, the exploitation of BMNPs in such fields has received a small amount of attention predominantly due to the vital lack of understanding and concerns mainly on the usage of other nanostructured materials, such as stability and bio-degradability over extended-time, ability to form clusters, chemical reactivity, and biocompatibility. In this review article, a close look at bimetallic nanomaterial based glucose biosensing approaches is discussed, concentrating on their clinical applications as detection of glucose in various real sample sources, showing substantial development of their features related to corresponding monometallic counterparts and other existing used nanomaterials for clinical applications.

Review on recent progress in metal-organic framework-based materials for fabricating electrochemical glucose sensors

Diabetes is a type of disease that threatens human health, which can be diagnosed based on the level of glucose in the blood. Recently, various MOF-based materials have been developed as efficient electrochemical glucose sensors because of their tunable pore channels, large specific surface area well dispersed metallic active sites, etc. In this review, the significance of glucose detection and the advantages of MOF-based materials for this application are primarily discussed. Then, the application of MOF-based materials can be categorized into two types of glucose sensors: enzymatic biosensors and non-enzymatic sensors. Finally, insights into the current research challenges and future breakthrough possibilities regarding electrochemical glucose sensors are considered.

Postmodulation of the Metal-Organic Framework Precursor toward the Vacancy-Rich CuxO Transducer for Sensitivity Boost: Synthesis, Catalysis, and H2O2 Sensing

Metal-organic frameworks (MOFs) act as versatile coordinators for the subsequent synthesis of high-performance catalysts by providing dispersed metal-ion distribution, initial coordination condition, dopant atom ratios, and so on. In this work, a crystalline MOF trans-[Cu(NO₃)₂(Him)₄] was synthesized as the novel precursor of a redox-alternating Cu_xO electrochemical catalyst. Through simple temperature modulation, the gradual transformation toward a highly active nanocomposite was characterized to ascertain the signal enhancing mechanism in H₂O₂ reduction. Owing to the proprietary structure of the transducer material and its ensuing high activity, a proof-of-principle sensor was able to provide an amplified sensitivity of 2330 μA mM^-1 cm^-2. The facile one-pot preparation and intrinsic nonenzymatic nature also suggests its wide potentials in medical settings.

Integrating the Essence of a Metal-Organic Framework with Electrospinning: A New Approach for Making a Metal Nanoparticle Confined N-Doped Carbon Nanotubes/Porous Carbon Nanofibrous Membrane for Energy Storage and Conversion

The fabrication of an economic and efficient multifunctional advanced nanomaterial with a rational composition and configuration by a facile methodology is a crucial challenge. Herein, we are the first to report the growth of Co nanoparticle-integrated nitrogen-doped carbon nanotubes (N-CNTs) on porous carbon nanofibers by simply heating in the situ-developed metal-organic framework (MOF)-based electrospun nanofibrous membrane with no need for an external supply of any additional precursors and reducing gases. The long and entangled N-CNTs originating from highly porous and graphitic carbon nanofibers offer good flexibility, large surface area, high porosity, high conductivity, the homogeneous incorporation of heteroatoms and metallic constituents, and an abundant exposure of active nanocatalytic sites. The as-developed nanoassembly demonstrates attractive characteristics for electrocatalytic hydrogen and oxygen evolution reactions and electrochemical energy storage. This strategy of integrating the essence of an MOF with electrospinning offers a new, direct, and cost-effective approach for making N-doped CNT-based multifunctional membranes.