The effect of montmorillonite functionalization on the performance of glucose biosensors based on composite montmorillonite/PAN nanofibers

Immobilization of Horseradish Peroxidase onto Montmorillonite/Glucosamine-Chitosan Composite for Electrochemical Biosensing of Polyphenols

Glucosamine-chitosan synthesized by the Maillard reaction was combined with montmorillonite to obtain a nanohybrid composite to immobilize horseradish peroxidase. The material combines the advantageous properties of clay with those of the chitosan derivative; has improved water solubility and reduced molecular weight and viscosity; involves an eco-friendly synthesis; and exhibits ion exchange capacity, good adhesiveness, and a large specific surface area for enzyme adsorption. The physicochemical characteristics of the composite were analyzed by infrared spectroscopy and X-ray diffraction to determine clay-polycation interactions. The electrochemical response of the different polyphenols to glassy carbon electrodes modified with the composite was evaluated by cyclic voltammetry. The sensitivity and detection limit values obtained with the biosensor toward hydroquinone, chlorogenic acid, catechol, and resorcinol are (1.6 ± 0.2) × 102 µA mM-1 and (74 ± 8) nM; (1.2 ± 0.1) × 102 µA mM-1 and (26 ± 3) nM; (16 ± 2) µA mM-1 and (0.74 ± 0.09) μM; and (3.7± 0.3) µA mM-1 and (3.3 ± 0.2) μM, respectively. The biosensor was applied to quantify polyphenols in pennyroyal and lemon verbena extracts.

Electrospun nanofiber-based glucose sensors for glucose detection

Diabetes is a chronic, systemic metabolic disease that leads to multiple complications, even death. Meanwhile, the number of people with diabetes worldwide is increasing year by year. Sensors play an important role in the development of biomedical devices. The development of efficient, stable, and inexpensive glucose sensors for the continuous monitoring of blood glucose levels has received widespread attention because they can provide reliable data for diabetes prevention and diagnosis. Electrospun nanofibers are new kinds of functional nanocomposites that show incredible capabilities for high-level biosensing. This article reviews glucose sensors based on electrospun nanofibers. The principles of the glucose sensor, the types of glucose measurement, and the glucose detection methods are briefly discussed. The principle of electrospinning and its applications and advantages in glucose sensors are then introduced. This article provides a comprehensive summary of the applications and advantages of polymers and nanomaterials in electrospun nanofiber-based glucose sensors. The relevant applications and comparisons of enzymatic and non-enzymatic nanofiber-based glucose sensors are discussed in detail. The main advantages and disadvantages of glucose sensors based on electrospun nanofibers are evaluated, and some solutions are proposed. Finally, potential commercial development and improved methods for glucose sensors based on electrospinning nanofibers are discussed.

Ag/AgBr/AgVO3 Photocatalyst-Embedded Polyacrylonitrile/Polyamide/Chitosan Nanofiltration Membrane for Integrated Filtration and Degradation of RhB

A nanofiltration (NF) membrane containing a NaOH-treated electrospun polyacrylonitrile (HPAN) substrate, an interfacial polymerization (IP) polyamide (PA) layer, a chitosan (CS) coating layer, and an Ag/AgBr/AgVO₃ photocatalyst loading layer was prepared. The structural evolution of the membranes was investigated, and their performance was estimated in accordance with the water flux and rejection rate. A probable mechanism for the photocatalytic activity of Ag/AgBr/AgVO₃ was proposed. The loading of the Ag/AgBr/AgVO₃ heterojunction on the HPAN/PA/CS NF membrane endowed the membrane with excellent self-cleaning properties owing to the photolytic degradation of the dye. The filtration and degradation processes of the Ag/AgBr/AgVO₃-loaded membrane constantly promoted each other, and the treatment efficiency achieved with the integrated (filtration + degradation) process was superior to those obtained with the filtration and degradation processes alone. The Ag/AgBr/AgVO₃-NF membrane exhibited excellent recyclability and stability when subjected to five integrated filtration-degradation processes. In addition, the Ag/AgBr/AgVO₃-NF membrane exhibited an elastic modulus of 65.75 MPa and a toughness of 38.9 kJ/m³ along with a good disinfection effect on Escherichia coli in visible light. The as-prepared photocatalyst-loaded NF membrane with excellent antifouling performance, antimicrobial activity, high strength, and recyclability showed potential for continuous water purification operation.

Design of composite nanosupports and applications thereof in enzyme immobilization: A review

Enzyme immobilization techniques have developed dramatically over the past several decades. Support materials are key in shaping the function of a specific immobilized enzyme. Although they have large specific surface areas and functional active sites, single-component nanomaterials and their surface chemical modification derivatives struggle to meet increasing demand. Thus, composite materials, compounds of two or more materials, have been developed and applied in efficient immobilization through advances in materials science. More methods have been developed and employed to design composite nanomaterials in recent years. These novel composite nanomaterials often show superior physical, chemical, and biological performance as supports in enzyme immobilization, among other applications. In this review, immobilization techniques and their supports are stated first and methods to design and fabricate composite nanomaterials as nanosupports are also shown in the following section. Applications of composite nanosupports in laccase immobilization are discussed as models in the later sections of the paper. This review is intended to help readers gain insight into the design principles of composite nanomaterials for immobilization supports.

Nano-Scaled Materials and Polymer Integration in Biosensing Tools

The evolution of biosensors and diagnostic devices has been thriving in its ability to provide reliable tools with simplified operation steps. These evolutions have paved the way for further advances in sensing materials, strategies, and device structures. Polymeric composite materials can be formed into nanostructures and networks of different types, including hydrogels, vesicles, dendrimers, molecularly imprinted polymers (MIP), etc. Due to their biocompatibility, flexibility, and low prices, they are promising tools for future lab-on-chip devices as both manufacturing materials and immobilization surfaces. Polymers can also allow the construction of scaffold materials and 3D structures that further elevate the sensing capabilities of traditional 2D biosensors. This review discusses the latest developments in nano-scaled materials and synthesis techniques for polymer structures and their integration into sensing applications by highlighting their various structural advantages in producing highly sensitive tools that rival bench-top instruments. The developments in material design open a new door for decentralized medicine and public protection that allows effective onsite and point-of-care diagnostics.

Smart nanofibres for specific and ultrasensitive nanobiosensors and drug delivery systems

Biosensors are dynamically developing analytical devices for the detection of substrates or other bioactive substances. They can be used for quick gas or liquid analyses and the construction of sensitive detection systems. This review highlights the advances and development of biosensors suitable for human and veterinary medicine and, namely, a novel contribution of nanotechnology for ultrasensitive diagnosis and personalized medicine. The synergic effect of nanotechnology and biosensors opens a new dimension for effective treatment and disease detection at their early stages.

Recent advances in polymer scaffolds for biomedical applications

The review provides insights into current advancements in electrospinning-assisted manufacturing for optimally designing biomedical devices for their prospective applications in tissue engineering, wound healing, drug delivery, sensing, and enzyme immobilization, and others. Further, the evolution of electrospinning-based hybrid biomedical devices using a combined approach of 3 D printing and/or film casting/molding, to design dimensionally stable membranes/micro-nanofibrous assemblies/patches/porous surfaces, etc. is reported. The influence of various electrospinning parameters, polymeric material, testing environment, and other allied factors on the morphological and physico-mechanical properties of electrospun (nano-/micro-fibrous) mats (EMs) and fibrous assemblies have been compiled and critically discussed. The spectrum of operational research and statistical approaches that are now being adopted for efficient optimization of electrospinning process parameters so as to obtain the desired response (physical and structural attributes) has prospectively been looked into. Further, the present review summarizes some current limitations and future perspectives for modeling architecturally novel hybrid 3 D/selectively textured structural assemblies, such as biocompatible, non-toxic, and bioresorbable mats/scaffolds/membranes/patches with apt mechanical stability, as biological substrates for various regenerative and non-regenerative therapeutic devices.

New Trends in Nanoclay-Modified Sensors

Nanoclays are widespread materials characterized by a layered structure in the nano-scale range. They have multiple applications in diverse scientific and industrial areas, mainly due to their swelling capacity, cation exchange capacity, and plasticity. Due to the cation exchange capacity, nanoclays can serve as host matrices for the stabilization of several molecules and, thus, they can be used as sensors by incorporating electroactive ions, biomolecules as enzymes, or fluorescence probes. In this review, the most recent applications as bioanalyte sensors are addressed, focusing on two main detection systems: electrochemical and optical methods. Particularly, the application of electrochemical sensors with clay-modified electrodes (CLME) for pesticide detection is described. Moreover, recent advances of both electrochemical and optical sensors based on nanoclays for diverse bioanalytes’ detection such as glucose, H2O2, organic acids, proteins, or bacteria are also discussed. As it can be seen from this review, nanoclays can become a key factor in sensors’ development, creating an emerging technology for the detection of bioanalytes, with application in both environmental and biomedical fields.

Application of Electrospun Nanofibers for Fabrication of Versatile and Highly Efficient Electrochemical Devices: A Review

Electrochemical devices convert chemical reactions into electrical energy or, vice versa, electricity into a chemical reaction. While batteries, fuel cells, supercapacitors, solar cells, and sensors belong to the galvanic cells based on the first reaction, electrolytic cells are based on the reversed process and used to decompose chemical compounds by electrolysis. Especially fuel cells, using an electrochemical reaction of hydrogen with an oxidizing agent to produce electricity, and electrolytic cells, e.g., used to split water into hydrogen and oxygen, are of high interest in the ongoing search for production and storage of renewable energies. This review sheds light on recent developments in the area of electrospun electrochemical devices, new materials, techniques, and applications. Starting with a brief introduction into electrospinning, recent research dealing with electrolytic cells, batteries, fuel cells, supercapacitors, electrochemical solar cells, and electrochemical sensors is presented. The paper concentrates on the advantages of electrospun nanofiber mats for these applications which are mostly based on their high specific surface area and the possibility to tailor morphology and material properties during the spinning and post-treatment processes. It is shown that several research areas dealing with electrospun parts of electrochemical devices have already reached a broad state-of-the-art, while other research areas have large space for future investigations.

Paper and Other Fibrous Materials-A Complete Platform for Biosensing Applications

Paper-based analytical devices (PADs) and Electrospun Fiber-Based Biosensors (EFBs) have aroused the interest of the academy and industry due to their affordability, sensitivity, ease of use, robustness, being equipment-free, and deliverability to end-users. These features make them suitable to face the need for point-of-care (POC) diagnostics, monitoring, environmental, and quality food control applications. Our work introduces new and experienced researchers in the field to a practical guide for fibrous-based biosensors fabrication with insight into the chemical and physical interaction of fibrous materials with a wide variety of materials for functionalization and biofunctionalization purposes. This research also allows readers to compare classical and novel materials, fabrication techniques, immobilization methods, signal transduction, and readout. Moreover, the examined classical and alternative mathematical models provide a powerful tool for bioanalytical device designing for the multiple steps required in biosensing platforms. Finally, we aimed this research to comprise the current state of PADs and EFBs research and their future direction to offer the reader a full insight on this topic.

Facile copper-based nanofibrous matrix for glucose sensing: Eenzymatic vs. non-enzymatic

The current study aims to provide a valid comparison between glucose detection efficiency with an enzymatic and a non-enzymatic sensing platform. A low-cost nano-matrix for glucose sensing was developed by drop-coating copper nanoparticles (Cu NPs) onto a polyacrylonitrile (PAN) electrospun nanofibrous assembly. The PAN NFs/Cu NPs matrix was optimized regarding electrospinning time and Cu NPs content and employed as a non-enzymatic sensor or further modified by cross-linking of glucose oxidase (GOD) for the development of an enzymatic sensor. The non-enzymatic glucose sensor was three times more sensitive (300 mAM^-1cm^-2) than the enzymatic one (81 mAM^-1cm^-2) with similar limit of detection values (5.9 and 5.6 µM, respectively). Incorporation of MWCNTs improved both the LOD (3.3 µM) and the operational stability of the non-enzymatic configuration (RSD 7.3%). The interference effect proved insignificant for the enzymatic sensor due to the innate catalytic selectivity whilst the non-enzymatic sensor acquired selectivity due to the nanofibrous PAN matrix and Nafion coating. The non-enzymatic PAN NFs/Cu NPs sensor was chosen for the detection of glucose in real blood serum samples whilst the PAN NFs/Cu NPs/GOD sensor was applied for glucose detection in fruit juices, both proving recovery results close to 100%.

Electrospinning nanofiber technology: a multifaceted paradigm in biomedical applications

This review focuses on the process of preparation of nanofibers via Es, the design and setup of the instrument, critical parameter optimization, preferable polymers, solvents, characterization techniques, and recent development and biomedical applications of nanofibers.