Electrospun Chitosan-Gelatin Biopolymer Composite Nanofibers for Horseradish Peroxidase Immobilization in a Hydrogen Peroxide Biosensor

Glyoxal crosslinking of electro-responsive alginate-based hydrogels: Effects on the properties

To improve the features of alginate-based hydrogels in physiological conditions, Ca2+-crosslinked semi-interpenetrated hydrogels formed by poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid and alginate (PEDOT/Alg) were subjected to a treatment with glyoxal to form a dual ionic/covalent network. The covalent network density was systematically varied by considering different glyoxalization times (tG). The content of Ca2+ was significantly higher for the untreated hydrogel than for the glyoxalized ones, while the properties of the hydrogels were found to largely depend on tG. The porosity and swelling capacity decreased with increasing tG, while the stiffness and electrical conductance retention capacity increased with tG. The potentiodynamic response of the hydrogels notably depended on the amount of conformational restraints introduced by the glyoxal, which is a very short crosslinker. Thus, the re-accommodation of the polymer chains during the cyclic potential scans became more difficult with increasing number of covalent crosslinks. This information was used to improve the performance of untreated PEDOT/Alg as electrochemical sensor of hydrogen peroxide by simply applying a tG of 5 min. Overall, the control of the properties of glyoxalized hydrogels through tG is very advantageous and can be used as an on-demand strategy to improve the performance of such materials depending on the application.

Fabrication and characterization of glucose-oxidase-trehalase electrode based on nanomaterial-coated carbon paper

Multienzyme systems are essential for utilizing di-, oligo-, and polysaccharides as fuels in enzymatic fuel cells effectively. However, the transfer of electrons generated by one enzymatic reaction in a multienzyme cascade at the electrode may be impeded by other enzymes, potentially hindering the overall efficiency. In this study, carbon paper was first modified by incorporating single-walled carbon nanotubes (SWCNTs) and gold nanoparticles (AuNPs) sequentially. Subsequently, glucose oxidase (GOx) and a trehalase-gelatin mixture were immobilized separately on the nanostructured carbon paper via layer-by-layer adsorption to mitigate the electron transfer hindrance caused by trehalase. The anode was first fabricated by immobilizing GOx and trehalase on the modified carbon paper, and the cathode was then fabricated by immobilizing bilirubin oxidase on the nanostructured electrode. The SWCNTs and AuNPs were distributed adequately on the electrode surface, which improved the electrode performance, as demonstrated by electrochemical and morphological analyses. An enzymatic fuel cell was assembled and tested using trehalose as the fuel, and a maximum power density of 23 μW cm-2 was obtained at a discharge current density of 60 μA cm-2. The anode exhibited remarkable reusability and stability.

Biopolymers Used for Receptor Immobilization for Nickel-Detection Biosensors in Food

Food is humans' main source of nickel intake, which is responsible for the prevalence of allergic contact dermatitis and other pathological afflictions. While robust, the classical methods for nickel detection-atomic absorption spectrometry and inductively coupled plasma mass spectrometry-are expensive and laborious; in contrast, modern methods that utilize sensors-of which most are electrochemical-have rapid run times, are cost-effective, and are easily assembled. Here, we describe the use of four biopolymers (alginate, agar, chitosan, and carrageenan) for receptor immobilization on biosensors to detect nickel ions and use an optimization approach with three biopolymer concentrations to assay analytical performance profiles. We measured the total performance of screen-printed carbon electrodes immobilized with the biopolymer-sensor combinations using cyclic voltammetry (CV). Voltammetric behavior favored the carrageenan biosensor, based on performance characteristics measured using CV, with sensitivities of 2.68 (for 1% biopolymer concentration) and 2.08 (for 0.5% biopolymer concentration). Our results indicated that among the four biopolymer combinations, carrageenan with urease affixed to screen-printed electrodes was effective at coupling for nickel detection.

A Review of Chitosan and Chitosan Nanofiber: Preparation, Characterization, and Its Potential Applications

Chitosan is produced by deacetylating the abundant natural chitin polymer. It has been employed in a variety of applications due to its unique solubility as well as its chemical and biological properties. In addition to being biodegradable and biocompatible, it also possesses a lot of reactive amino side groups that allow for chemical modification and the creation of a wide range of useful derivatives. The physical and chemical characteristics of chitosan, as well as how it is used in the food, environmental, and medical industries, have all been covered in a number of academic publications. Chitosan offers a wide range of possibilities in environmentally friendly textile processes because of its superior absorption and biological characteristics. Chitosan has the ability to give textile fibers and fabrics antibacterial, antiviral, anti-odor, and other biological functions. One of the most well-known and frequently used methods to create nanofibers is electrospinning. This technique is adaptable and effective for creating continuous nanofibers. In the field of biomaterials, new materials include nanofibers made of chitosan. Numerous medications, including antibiotics, chemotherapeutic agents, proteins, and analgesics for inflammatory pain, have been successfully loaded onto electro-spun nanofibers, according to recent investigations. Chitosan nanofibers have several exceptional qualities that make them ideal for use in important pharmaceutical applications, such as tissue engineering, drug delivery systems, wound dressing, and enzyme immobilization. The preparation of chitosan nanofibers, followed by a discussion of the biocompatibility and degradation of chitosan nanofibers, followed by a description of how to load the drug into the nanofibers, are the first issues highlighted by this review of chitosan nanofibers in drug delivery applications. The main uses of chitosan nanofibers in drug delivery systems will be discussed last.

Recent trends using natural polymeric nanofibers as supports for enzyme immobilization and catalysis

All the disciplines of science, especially biotechnology, have given continuous attention to the area of enzyme immobilization. However, the structural support made by material science intervention determines the performance of immobilized enzymes. Studies have proven that nanostructured supports can maintain better catalytic performance and improve immobilization efficiency. The recent trends in the application of nanofibers using natural polymers for enzyme immobilization have been addressed in this review article. A comprehensive survey about the immobilization strategies and their characteristics are highlighted. The natural polymers, e.g., chitin, chitosan, silk fibroin, gelatin, cellulose, and their blends with other synthetic polymers capable of immobilizing enzymes in their 1D nanofibrous form, are discussed. The multiple applications of enzymes immobilized on nanofibers in biocatalysis, biosensors, biofuels, antifouling, regenerative medicine, biomolecule degradation, etc.; some of these are discussed in this review article.

Fabrication and characterization of polycaprolactone/cellulose acetate blended nanofiber mats containing sericin and fibroin for biomedical application

Polycaprolactone/cellulose acetate blended nanofiber mats containing sericin and fibroin were fabricated by electrospinning process to study the effect of sericin and fibroin on the physical and structural properties, wettability, degradability, elastic modulus, cell adhesion, and cell cytotoxicity of the electrospun nanofibers. Polycaprolactone/cellulose acetate solution was prepared with different percentage ratio of sericin and fibroin to be the running solution. Nanofibers were spun at fixed solution flow rate, flying distance, and operating voltage. The diameter of the obtained nanofibers linearly increases with the increasing of the sericin ratio. The derivative structures of polycaprolactone, cellulose acetate, sericin, and fibroin of the obtained nanofibers were confirmed by FTIR analysis. All acquired nanofibers show superhydrophilicity with adequate time of degradation for L-929 cell adhesion and growth. More elasticity is gained when the sericin ratio decreases. Moreover, all fibers containing sericin/fibroin reveal more elasticity, cell adhesion, and cell growth than that with only polycaprolactone/cellulose acetate. Greater cell adhesion and growth develop when the sericin ratio is lower. All the fabricated nanofibers are low toxic to the cells. Fibers with a mixture of sericin and fibroin at 2.5:2.5 (% w/v) are the most promising and suitable for further clinical development due to their good results in each examination. The novelty found in this study is not only making more value of the sericin, silk industrial waste, and the fibroin, but also getting the preferable biomaterials, scaffold prototype, with much greater mechanical property and slower degradation, which are required and appropriate for cell attachment and proliferation of cell generation process, compared to that obtaining from polycaprolactone/cellulose acetate or sericin/fibroin nanofibers.

Biopolymer-based electrospun fibers in electrochemical devices: versatile platform for energy, environment, and health monitoring

Electrochemical power tools are regarded as essential keys in a world that is becoming increasingly reliant on fossil fuels in order to meet the challenges of rapidly depleting fossil fuel supplies. Additionally, due to the industrialization of societies and the growth of diseases, the need for sensitive, reliable, inexpensive, and portable sensors and biosensors for noninvasive monitoring of human health and environmental pollution is felt more than ever before. In recent decades, electrospun fibers have emerged as promising candidates for the fabrication of highly efficient electrochemical devices, such as actuators, batteries, fuel cells, supercapacitors, and biosensors. Meanwhile, the use of synthetic polymers in the fabrication of versatile electrochemical devices has raised environmental concerns, leading to an increase in the quest for natural polymers. Natural polymers are primarily derived from microorganisms and plants. Despite the challenges of processing bio-based electrospun fibers, employing natural nanofibers in the fabrication of electrochemical devices has garnered tremendous attention in recent years. Here, various natural polymers and the strategies employed to fabricate various electrospun biopolymers are briefly covered. The recent advances and research strategies used to apply the bio-based electrospun membranes in different electrochemical devices are carefully summarized, along with the scopes in various advanced technologies. A comprehensive and critical discussion about the use of biopolymer-based electrospun fibers as the potential alternative to non-renewable ones in future technologies is briefly highlighted. This review will serve as a field opening platform for using different biopolymer-based electrospun fibers to advance the electrochemical device-based renewable and sustainable technologies, which will be of high interest to a large community. Accordingly, future studies should focus on feasible and cost-effective extraction of biopolymers from natural resources as well as fabrication of high-performance nanofibrous biopolymer-based components applicable in various electrochemical devices.

Applications of Gelatin in Biosensors: Recent Trends and Progress

Gelatin is a natural protein from animal tissue with excellent biocompatibility, biodegradability, biosafety, low cost, and sol-gel property. By taking advantage of these properties, gelatin is considered to be an ideal component for the fabrication of biosensors. In recent years, biosensors with gelatin have been widely used for detecting various analytes, such as glucose, hydrogen peroxide, urea, amino acids, and pesticides, in the fields of medical diagnosis, food testing, and environmental monitoring. This perspective is an overview of the most recent trends and progress in the development of gelatin-based biosensors, which are classified by the function of gelatin as a matrix for immobilized biorecognition materials or as a biorecognition material for detecting target analytes.

Medical applications of biopolymer nanofibers

A wide array of biomedical applications, extending from the fabrication of implant materials to targeted drug delivery, can be attributed to polymers. The utilization of chemical monomers to form polymers, such as polypropylene, polystyrene, and polyethylene, can provide high mechanical stability to them and they can be utilized for diverse electronic or thermal applications. However, certain chemical-based synthetic polymers are toxic to humans, animals, plants, and microbial cells. Thus, biopolymers have been introduced as an alternative to make them utilizable for biomedical applications. Even though biopolymers possess beneficial biomedical applications, they are not stable in biological fluids and exhibit toxicity in certain cases. Recent advances in nanotechnology have expanded its applicational significance in various domains, especially in the evolution of biopolymers to transform them into nanoparticles for numerous biomedical applications. In particular, biopolymers are fabricated as nanofibers to enhance their biological properties and to be utilized for exclusive biomedical applications. The aim of this review is to present an overview of various biopolymer nanofibers and their distinct synthesis approaches. In addition, the medical applications of biopolymer nanofibers, including antimicrobial agents, drug delivery systems, biosensor production, tissue engineering, and implant fabrication, are also discussed.

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.

Hybrid Gelatin Hydrogels in Nanomedicine Applications

Gelatin based hydrogels are often incorporated with supporting materials such as chitosan, poly(vinyl alcohol), alginate, carbon nanotubes, and hyaluronic acid. These hybrid materials are specifically of interest in diversified nanomedicine fields as they exhibit unique physicochemical properties, antimicrobial activity, biodegradability, and biocompatibility. The applications include drug delivery, wound healing, cell culture, and tissue engineering. This paper reviews the various up-to-date methods to fabricate gelatin-based hydrogels, including UV photo-cross-linking, electrospinning, and 3D bioprinting. This paper also includes physical, chemical, mechanical, and biocompatibility characterization studies of several hybrid gelatin hydrogels and discusses their relevance in nanomedicine based applications. Challenges associated with the fabrication of hybrid materials for nanotechnology implementation, specifically in nanomedicine development, are critically discussed, and some future recommendations are provided.

A, Adnan AS, Alqadhi AM, Abdullah CK, A.K. AS, Olaiya NG, Abdat M. The Role of Biopolymer-Based Materials in Obstetrics and Gynecology Applications: A Review

Biopolymers have gained tremendous attention in many daily life applications, including medical applications, in the past few years. Obstetrics and gynecology are two fields dealing with sensitive parts of the woman's body and her newborn baby, which are normally associated with many issues such as toxicity, infections, and even gene alterations. Medical professions that use screening, examination, pre, and post-operation materials should benefit from a better understanding of each type of material's characteristics, health, and even environmental effects. The underlying principles of biopolymer-based materials for different obstetric and gynecologic applications may discover various advantages and benefits of using such materials. This review presents the health impact of conventional polymer-based materials on pregnant women's health and highlights the potential use of biopolymers as a safer option. The recent works on utilizing different biopolymer-based materials in obstetric and gynecologic are presented in this review, which includes suture materials in obstetric and gynecologic surgeries, cosmetic and personal care products, vaginal health, and drug delivery; as well as a wound dressing and healing materials. This review highlights the main issues and challenges of biopolymers in obstetric and gynecologic applications.

Nanostructured materials as a host matrix to develop robust peroxidases-based nanobiocatalytic systems

Nanostructured materials constitute an interesting and novel class of support matrices for the immobilization of peroxidase enzymes. Owing to the high surface area, robust mechanical stability, outstanding optical, thermal, and electrical properties, nanomaterials have been rightly perceived as immobilization matrices for enzyme immobilization with applications in diverse areas such as nano-biocatalysis, biosensing, drug delivery, antimicrobial activities, solar cells, and environmental protection. Many nano-scale materials have been employed as support matrices for the immobilization of different classes of enzymes. Nanobiocatalysts, enzymes immobilized on nano-size materials, are more stable, catalytically robust, and could be reused and recycled in multiple reaction cycles. In this review, we illustrate the unique structural/functional features and potentialities of nanomaterials-immobilized peroxidase enzymes in different biotechnological applications. After a comprehensive introduction to the immobilized enzymes and nanocarriers, the first section reviewed carbonaceous nanomaterials (carbon nanotube, graphene, and its derivatives) as a host matrix to constitute robust peroxidases-based nanobiocatalytic systems. The second half covers metallic nanomaterials (metals, and metal oxides) and some other novel materials as host carriers for peroxidases immobilization. The next section vetted the potential biotechnological applications of the resulted nanomaterials-immobilized robust peroxidases-based nanobiocatalytic systems. Concluding remarks, trends, and future recommendations for nanomaterial immobilized enzymes are also given.

Enzyme-like electrocatalysis from 2D gold nanograss-nanocube assemblies

Nanotechnology's rapid development of nanostructured materials with disruptive material properties has inspired research for their use as electrocatalysts to potentially substitute enzymes. Herein, a novel electrocatalytic nanomaterial was constructed by growing gold nanograss (AuNG) on 2D nanoassemblies of gold nanocubes (AuNC). The resulting structure (NG@NC) was used for the detection of H₂O₂via its electrochemical reduction. The NG@NC electrode displayed a large active surface area, resulting in improved electron transfer efficiency. On the nanoscale, AuNG maintained its structure, providing high stability and reproducibility of the sensing platform. Our nanostructured electrode showed excellent catalytic activity towards H₂O₂ at an applied potential of -0.5 V vs Ag/AgCl. This facilitated H₂O₂ detection with excellent selectivity in an environment like human urine, and a linear response from 50 µM to 30 mM, with a sensitivity of 100.66 ± 4.0 μA mM^-1 cm^-2. The NG@NC-based sensor hence shows great potential in nonenzymatic electrochemical sensing.

Tunable Polymeric Scaffolds for Enzyme Immobilization

The number of methodologies for the immobilization of enzymes using polymeric supports is continuously growing due to the developments in the fields of biotechnology, polymer chemistry, and nanotechnology in the last years. Despite being excellent catalysts, enzymes are very sensitive molecules and can undergo denaturation beyond their natural environment. For overcoming this issue, polymer chemistry offers a wealth of opportunities for the successful combination of enzymes with versatile natural or synthetic polymers. The fabrication of functional, stable, and robust biocatalytic hybrid materials (nanoparticles, capsules, hydrogels, or films) has been proven advantageous for several applications such as biomedicine, organic synthesis, biosensing, and bioremediation. In this review, supported with recent examples of enzyme-protein hybrids, we provide an overview of the methods used to combine both macromolecules, as well as the future directions and the main challenges that are currently being tackled in this field.

Electrochemical Sensor Based on Prussian Blue Electrochemically Deposited at ZrO2 Doped Carbon Nanotubes Glassy Carbon Modified Electrode

In this work, a new hydrogen peroxide (H₂O₂) electrochemical sensor was fabricated. Prussian blue (PB) was electrodeposited on a glassy carbon (GC) electrode modified with zirconia doped functionalized carbon nanotubes (ZrO₂-fCNTs), (PB/ZrO₂-fCNTs/GC). The morphology and structure of the nanostructured system were characterized by scanning and transmission electron microscopy (TEM), atomic force microscopy (AFM), specific surface area, X-ray diffraction (XRD), thermogravimetric analysis (TGA), Raman and Fourier transform infrared (FTIR) spectroscopy. The electrochemical properties were studied by cyclic voltammetry (CV) and chronoamperometry (CA). Zirconia nanocrystallites (6.6 ± 1.8 nm) with cubic crystal structure were directly synthesized on the fCNTs walls, obtaining a well dispersed distribution with a high surface area. The experimental results indicate that the ZrO₂-fCNTs nanostructured system exhibits good electrochemical properties and could be tunable by enhancing the modification conditions and method of synthesis. The fabricated sensor could be used to efficiently detect H₂O₂, presenting a good linear relationship between the H₂O₂ concentration and the peak current, with quantification limit (LQ) of the 10.91 μmol·L^-1 and detection limit (LD) of 3.5913 μmol·L^-1.

Peroxide Electrochemical Sensor and Biosensor Based on Nanocomposite of TiO2 Nanoparticle/Multi-Walled Carbon Nanotube Modified Glassy Carbon Electrode

A hydrogen peroxide (H₂O₂) sensor and biosensor based on modified multi-walled carbon nanotubes (CNTs) with titanium dioxide (TiO₂) nanostructures was designed and evaluated. The construction of the sensor was performed using a glassy carbon (GC) modified electrode with a TiO₂–CNT film and Prussian blue (PB) as an electrocalatyzer. The same sensor was also employed as the basis for H₂O₂ biosensor construction through further modification with horseradish peroxidase (HRP) immobilized at the TiO₂–fCNT film. Functionalized CNTs (fCNTs) and modified TiO₂–fCNTs were characterized by Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), and X-Ray DifFraction (XRD), confirming the presence of anatase over the fCNTs. Depending on the surface charge, a solvent which optimizes the CNT dispersion was selected: dimethyl formamide (DMF) for fCNTs and sodium dodecylsulfate (SDS) for TiO₂–fCNTs. Calculated values for the electron transfer rate constant (ks) were 0.027 s⁻¹ at the PB–fCNT/GC modified electrode and 4.7 × 10⁻⁴ s⁻¹ at the PB–TiO₂/fCNT/GC electrode, suggesting that, at the PB–TiO₂/fCNT/GC modified electrode, the electronic transfer was improved. According to these results, the PB–fCNT/GC electrode exhibited better Detection Limit (LD) and Quantification Limit (LQ) than the PB–TiO₂/fCNT/GC electrode for H₂O₂. However, the PB film was very unstable at the potentials used. Therefore, the PB–TiO₂/fCNT/GC modified electrode was considered the best for H₂O₂ detection in terms of operability. Cyclic Voltammetry (CV) behaviors of the HRP–TiO₂/fCNT/GC modified electrodes before and after the chronoamperometric test for H₂O₂, suggest the high stability of the enzymatic electrode. In comparison with other HRP/fCNT-based electrochemical biosensors previously described in the literature, the HRP–fCNTs/GC modified electrode did not show an electroanalytical response toward H₂O₂.

"Fishing and Hunting"-Selective Immobilization of a Recombinant Phenylalanine Ammonia-Lyase from Fermentation Media

This article overviews the numerous immobilization methods available for various biocatalysts such as whole-cells, cell fragments, lysates or enzymes which do not require preliminary enzyme purification and introduces an advanced approach avoiding the costly and time consuming downstream processes required by immobilization of purified enzyme-based biocatalysts (such as enzyme purification by chromatographic methods and dialysis). Our approach is based on silica shell coated magnetic nanoparticles as solid carriers decorated with mixed functions having either coordinative binding ability (a metal ion complexed by a chelator anchored to the surface) or covalent bond-forming ability (an epoxide attached to the surface via a proper linker) enabling a single operation enrichment and immobilization of a recombinant phenylalanine ammonia-lyase from parsley fused to a polyhistidine affinity tag.

Naturally-derived biopolymers: Potential platforms for enzyme immobilization

Naturally-derived biopolymers such as alginate, chitosan, cellulose, agarose, guar gum/guaran, agar, carrageenan, gelatin, dextran, xanthan, and pectins, etc. have appealed significant attention over the past several years owing to their natural abundance and availability all over the years, around the globe. In addition, their versatile properties such as non-toxicity, biocompatibility, biodegradability, flexibility, renewability, and the availability of numerous reactive sites offer significant functionalities with multipurpose applications. At present, intensive research efforts have been focused on engineering enzymes using natural biopolymers as novel support/composite materials for diverse applications in biomedical, environmental, pharmaceutical, food and biofuel/energy sectors. Immobilization appears as a straightforward and promising approach to developing biocatalysts with improved catalytic properties as compared to their free counterparts. Biopolymers-assisted enzymes are more stable, robust, and recoverable than that of free forms, and can be employed for continuous biocatalytic reactions. The present review highlights the recent developments and use of biopolymers and their advanced composites as support carriers for the immobilization of a variety of different enzymes to develop biocatalysts with desired catalytic activity and stability characteristics for emerging applications.

Chitin/Chitosan: Versatile Ecological, Industrial, and Biomedical Applications

Chitin is a linear polysaccharide of N-acetylglucosamine, which is highly abundant in nature and mainly produced by marine crustaceans. Chitosan is obtained by hydrolytic deacetylation. Both polysaccharides are renewable resources, simply and cost-effectively extracted from waste material of fish industry, mainly crab and shrimp shells. Research over the past five decades has revealed that chitosan, in particular, possesses unique and useful characteristics such as chemical versatility, polyelectrolyte properties, gel- and film-forming ability, high adsorption capacity, antimicrobial and antioxidative properties, low toxicity, and biocompatibility and biodegradability features. A plethora of chemical chitosan derivatives have been synthesized yielding improved materials with suggested or effective applications in water treatment, biosensor engineering, agriculture, food processing and storage, textile additives, cosmetics fabrication, and in veterinary and human medicine. The number of studies in this research field has exploded particularly during the last two decades. Here, we review recent advances in utilizing chitosan and chitosan derivatives in different technical, agricultural, and biomedical fields.