Dextran-assisted ultrasonic exfoliation of two-dimensional metal-organic frameworks to evaluate acetylcholinesterase activity and inhibitor screening

Recent Advances in Nanozyme Sensors Based on Metal-Organic Frameworks and Covalent-Organic Frameworks

Nanozymes are nanomaterials that exhibit enzyme-like catalytic activity, which have drawn increasing attention on account of their unique superiorities including very high robustness, low cost, and ease of modification. Metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs) have emerged as promising candidates for nanozymes due to their abundant catalytic activity centers, inherent porosity, and tunable chemical functionalities. In this review, we first compare the enzyme-mimicking activity centers and catalytic mechanisms between MOF and COF nanozymes, and then summarize the recent research on designing and modifying MOF and COF nanozymes with inherent catalytic activity. Moreover, typical examples of sensing applications based on these nanozymes are presented, as well as the translation of enzyme catalytic activity into a visible signal response. At last, a discussion of current challenges is presented, followed by some future prospects to provide guidance for designing nanozyme sensors based on MOFs and COFs for practical applications.

Fe3O4@MXene@PEI aerogel immobilized acetylcholinesterase for inhibitor screening from herbal plants

Screening of acetylcholinesterase (AChE) inhibitors is a common strategy in drug discovery for treating Alzheimer's disease. Herein, AChE was immobilized onto magnetic polyethyleneimine-based MXene aerogels through both electrostatic interactions and covalent bonds, enabling its application in AChE activity assays and inhibitor screening of herbal plants. The composite was analyzed using a range of techniques, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and Zeta potential analysis, to gain insight into its chemical and physical properties. The proposed Fe3O4@MXene@PEI-AChE composite exhibited enhanced temperature and pH stability, as evaluated by Ellman's method, along with good reusability. The Michaelis Menten constant (Km) of the immobilized AChE was calculated to be 0.68 mmol/L. Additionally, an inhibition kinetic study was conducted to verify the feasibility of utilizing the immobilized enzyme to screen for inhibitors, with huperzine A employed as a model inhibitor. The proposed strategy was employed to compare the AChE inhibitory activity of 18 commonly used herbal medicines for treating AD, revealing both the aqueous and alcoholic extracts of Coptis chinensis as exhibiting the highest AChE inhibitory activity. Finally, the screening of AChE inhibitors in Coptis chinensis extracts were conducted by combining the proposed strategy with UPLC-Q-Orbitrap high resolution mass spectrometry. This study presents a feasible strategy for monitoring AChE activity and holds considerable potential for further exploration of AChE-inhibiting active ingredients in herbal medicines.

Advances in two-dimensional transition metal dichalcogenides-based sensors for environmental, food, and biomedical analysis: A review

Transition metal dichalcogenides (TMDCs) are versatile two-dimensional (2D) nanomaterials used in biosensing applications due to their excellent physical and chemical properties. Due to biomaterial target properties, biosensors' most significant challenge is improving their sensitivity and stability. In environmental analysis, TMDCs have demonstrated exceptional pollutant detection and removal capabilities. Their high surface area, tunable electronic properties, and chemical reactivity make them ideal for sensors and adsorbents targeting various contaminants, including heavy metals, organic pollutants, and emerging contaminants. Furthermore, their unique electronic and optical properties enable sensitive detection techniques, enhancing our ability to monitor and mitigate environmental pollution. In the food analysis, TMDCs-based nanomaterials have shown remarkable potential in ensuring food safety and quality. These nanomaterials exhibit high specificity and sensitivity for detecting contaminants, pathogens, and adulterants in various food matrices. Their integration into sensor platforms enables rapid and on-site analysis, reducing the reliance on centralized laboratories and facilitating timely interventions in the food supply chain. In biomedical studies, TMDCs-based nanomaterials have demonstrated significant strides in diagnostic and therapeutic applications. Their biocompatibility, surface functionalization versatility, and photothermal properties have paved the way for novel disease detection, drug delivery, and targeted therapy approaches. Moreover, TMDCs-based nanomaterials have shown promise in imaging modalities, providing enhanced contrast and resolution for various medical imaging techniques. This article provides a comprehensive overview of 2D TMDCs-based biosensors, emphasizing the growing demand for advanced sensing technologies in environmental, food, and biomedical analysis.

MOF-based nanocomposites as transduction matrices for optical and electrochemical sensing

Metal Organic Frameworks (MOFs), a class of crystalline microporous materials have been into research limelight lately due to their commendable physio-chemical properties and easy fabrication methods. They have enormous surface area which can be a working ground for innumerable molecule adhesions and site for potential sensor matrices. Their biocompatibility makes them valuable for in vitro detection systems but a compromised conductivity requires a lot of surface engineering of these molecules for their usage in electrochemical biosensors. However, they are not just restricted to a single type of transduction system rather can also be modified to achieve feat as optical (colorimetry, luminescence) and electro-luminescent biosensors. This review emphasizes on recent advancements in the area of MOF-based biosensors with focus on various MOF synthesis methods and their general properties along with selective attention to electrochemical, optical and opto-electrochemical hybrid biosensors. It also summarizes MOF-based biosensors for monitoring free radicals, metal ions, small molecules, macromolecules and cells in a wide range of real matrices. Extensive tables have been included for understanding recent trends in the field of MOF-composite probe fabrication. The article sums up the future scope of these materials in the field of biosensors and enlightens the reader with recent trends for future research scope.

Copper(II)-MOFs for bio-applications

The recent development and implementation of copper-based metal-organic frameworks in biological applications are reviewed. The advantages of the presence of copper in MOFs for relevant applications such as drug delivery, cancer treatment, sensing, and antimicrobial are highlighted. Advanced composites such as MOF-polymers are playing critical roles in developing materials for specific applications.

Development of Two-Dimensional Functional Nanomaterials for Biosensor Applications: Opportunities, Challenges, and Future Prospects

New possibilities for the development of biosensors that are ready to be implemented in the field have emerged thanks to the recent progress of functional nanomaterials and the careful engineering of nanostructures. Two-dimensional (2D) nanomaterials have exceptional physical, chemical, highly anisotropic, chemically active, and mechanical capabilities due to their ultra-thin structures. The diversity of the high surface area, layered topologies, and porosity found in 2D nanomaterials makes them amenable to being engineered with surface characteristics that make it possible for targeted identification. By integrating the distinctive features of several varieties of nanostructures and employing them as scaffolds for bimolecular assemblies, biosensing platforms with improved reliability, selectivity, and sensitivity for the identification of a plethora of analytes can be developed. In this review, we compile a number of approaches to using 2D nanomaterials for biomolecule detection. Subsequently, we summarize the advantages and disadvantages of using 2D nanomaterials in biosensing. Finally, both the opportunities and the challenges that exist within this potentially fruitful subject are discussed. This review will assist readers in understanding the synthesis of 2D nanomaterials, their alteration by enzymes and composite materials, and the implementation of 2D material-based biosensors for efficient bioanalysis and disease diagnosis.