Electrospinning-based (bio)sensors for food and agricultural applications: A review

Incorporation of fucoidan into zein-based electrospun fibers: A promising material for biotechnological applications

Ultrafine fibers are gaining attention for their unique properties and wide-ranging applications. Among production techniques, electrospinning stands out for its cost-effectiveness, simplicity, and control over fiber structure and diameter. This study reports for the first time the development of ultrafine fibers using zein, a renewable protein, with the addition of fucoidan, a bioactive polysaccharide from brown algae, through electrospinning. Polymeric solutions of 30 % zein and varying concentrations of fucoidan (0 %, 25 %, 30 %, 35 %) were produced, with viscosity and electrical conductivity analyzed. Solutions with 25 % and 30 % fucoidan showed higher viscosity, while conductivity remained relatively stable. The hydrophilic nature of the solutions, indicated by contact angle analysis, favors cell adhesion and proliferation. Fourier transform infrared and X-ray diffraction analyses confirmed the material characteristics and amorphous nature of the fibers. Ultrafine fibers distribution averaged 540 ± 130 nm, with those incorporating 25 % and 30 % fucoidan forming ribbon shapes and smaller diameters (234 ± 54 nm and 276 ± 54 nm), which suggests improved fiber structure, potentially enhancing biological activity. Cytotoxicity tests on mouse fibroblast cells showed no toxic effects after 24 and 48 h, supporting the feasibility of further biological studies, including the potential use of these fibers as skin healing adhesives.

Polymeric Nanofibers via Green Electrospinning for Safe Food Engineering

Electrospun functional nanofibers enable controlled release of the loaded active ingredient and an adjustable dissolution rate. However, the widespread use of toxic organic solvents in electrospinning poses risks to human health and the environment whereas increasing production costs and complexity. This article examines the application of eco-friendly electrospinning technologies in food engineering, with a focus on water-based and melt electrospinning methods. It provides a detailed analysis of water-soluble biopolymers and synthetic polymers, highlighting their current applications and challenges in food engineering. Water-based electrospinning is proposed as a sustainable alternative, offering scalability and reduced environmental impact. This transition is essential for advancing food engineering toward more sustainable and environmentally responsible practices.

Advancing Frontiers: Graphene-Based Nano-biosensor Platforms for Cutting-Edge Research and Future Innovations

Graphene and its derivatives have excellent electrical, mechanical, and optical capabilities, making it the perfect foundation for sensing living things. Graphene-based nano biosensors have shown exceptional sensitivity, selectivity, and quick response times when used to detect a range of analytes, such as biomolecules, cells, and pathogens. The main uses of graphene-based nano biosensors are disease diagnosis, environmental monitoring, food safety, and drug development. It also explores prospective future strategies, such as methods for functionalizing nanomaterials, their incorporation with other nanomaterials, and the creation of wearable and implantable gadgets. Various signalling techniques, such as fluorescence, electrochemistry, surface plasmon resonance, surface-enhanced Raman scattering, etc., can be coupled with graphene-based biosensors to quantitatively detect disease-associated DNA, RNA, and protein biomarkers quantitatively. Graphene-based nano biosensors, combined with cutting-edge innovations like artificial intelligence and the Internet of Things, can completely transform industries like healthcare and environmental monitoring. Developing these biosensors with high sensitivity and low detection limits provides a new direction in medical and personal care. The later portion of the review covers the difficulties, prospective fixes, and opportunities of graphene-based biosensors.

Colorimetric core/shell ZIF-8/PEO/PDA nanofibers for detection of fish spoilage

Here, colorimetric nanofibers (NFs) based on polydiacetylene (PDA), zeolitic imidazolate framework-8 (ZIF-8), and poly(ethylene) oxide (PEO) were developed. First, the successful synthesis of ZIF-8 was illustrated with structural and morphological analysis. Next, shell/core PDA/PEO/ZIF-8 NFs, namely PPZ0, PPZ5, PPZ15, and PPZ25, were fabricated by coaxial electrospinning at various ZIF-8 concentrations in the core. PPZ5 NFs exhibited a 63 % increase in tensile strength while PPZ25 NFs showed the highest thermal resistance. PPZ15 NFs with the best physicochemical and colorimetric properties were selected to evaluate food spoilage. The change in color difference values of PPZ15 NFs was correlated well with total viable count (TVC) and total volatile basic nitrogenous (TVB-N) in fish samples during chilled storage, reaching TVC to 6.69 log CFU/g, and TVB-N to 33.13 mg N/100 g on day 6. Ultimately, the PPZ15 NFs were successfully utilized to provide a real-time, quantitative assessment of fish freshness.

Fluorescent sensing copolymers: Synthesis, nanofiber fabrication and application in picric acid sensors

Increasing attention has been paid to the detection of explosives due to the occurrence of terrorist attacks around the world. Here, we used free radical polymerization to develop two different types of fluorescent copolymers for use in detecting picric acid. One exhibits aggregation-caused quenching (ACQ) and is called PNNS [poly (N-isopropyl acrylamide-co-N-hydroxymethyl acrylamide -co-styrene-pyrene), poly (NIPAAm-co-NMA-co-St-Py)]. The other possesses aggregation-induced emission (AIE) properties and is called PNNP [poly (N-isopropyl acrylamide-co-N-hydroxymethyl acrylamide-co-2-(1,2,3,4,5-pentaphenyl-1H-silol-1-yloxy) ethyl methacrylate), poly (NIPAAm-co-NMA-co-PPS-HEMA)]. Nanofibrous thin films of these copolymers were obtained by electrospinning. Upon interaction with picric acid, the fluorescence intensity of each copolymer was quenched due to photo-induced electron transfer (PET). The average diameters of PNNS and PNNP nanofibers were 179 ± 28 nm and 235 ± 143 nm, respectively. Sensing performance was evaluated by Stern-Volmer analysis. The Stern-Volmer constant (Ksv) values for PNNS and PNNP nanofibers were 0.012 μΜ-1 and 0.119 μΜ-1, respectively. Since the aggregated state of PNNP nanofibrous thin films can increase dramatically, the AIE property of this material provides a large dynamic range. Finally, the reusability of water- and methanol-washed nanofiber thin films was tested, revealing that the nanofiber sensors were reusable for detecting picric acid.

Electrospinning-based sensing technologies: Opportunities for food applications

The article explores the science and practice of electrospinning, tracing its history and examining the factors that influence fiber morphology, including the solution composition, processing conditions, and environmental conditions. It offers a thorough examination of electrospinning fundamentals geared toward generating an appropriate platform for creating tailored nanofibers for sensing applications in the food industry. These nanofibers play a critical role in food analysis, sensing, and traceability, and we highlight their effectiveness in identifying pesticide residues, food components, antibiotics, heavy metals, and foodborne pathogens as well as in monitoring the freshness and spoilage of food. The use of electrospinning technology is poised to make sensing platforms more accessible, affordable, and widespread, thereby significantly contributing to the improvement of food quality and safety monitoring practices.

Electrospun Fiber Membrane with the Dual Affinity of Chelation and Covalent Interactions for the Efficient Enrichment of Glycoproteins

As important biomarkers of many diseases, glycoproteins are of great significance to biomedical science. It is essential to develop efficient glycoprotein enrichment platforms and investigate their adsorption mechanism. In this work, a conspicuous enrichment strategy for glycoproteins was developed by using an electrospun fiber membrane wrapped with polydopamine (PDA) and modified with 3-aminophenylboronic acid and nickel ions, named PAN/DA@PDA@APBA/Ni. The enrichment characteristics of PAN/DA@PDA@APBA/Ni toward glycoproteins were explored through adsorption behavior. Thanks to the existence of two sites of interaction (metal ion chelation and boronate affinity), PAN/DA@PDA@APBA/Ni exhibited significant enrichment capacity for glycoproteins, ovalbumin (604.6 mg/g), and human immunoglobulin G (331.0 mg/g). The adsorption kinetic results of glycoprotein ovalbumin on PAN/DA@PDA@APBA/Ni conform to the pseudo-first-order kinetic model in the first adsorption stage, while the second half adsorption stage is more in line with the pseudo-second-order kinetic model. Moreover, the physical characteristics of PAN/DA@PDA@APBA/Ni and subsequent adsorption experiments on electrospun fiber modified with only phenylboronic acid or nickel ions both confirmed two sites of interaction (metal ion chelation and boronate affinity, respectively). Furthermore, a stepwise elution method with dual-affinity interaction was designed and successfully applied to enrich glycoproteins in real biological samples. This work provides an idea for sample pretreatment, especially for the design of dual-affinity materials in glycoproteins enrichment.

Nano-fibre matrix loaded with multi-nutrients to achieve balanced crop nutrition in greengram (Vigna radiata L.)

This research paper focuses on exploring the possibility of delivering macro, micro and trace elements using seed encapsulation through nano-fibres that are known to improve the nutrient use efficiencies while reducing the loss of nutrients. The nano-fibres were developed using an electrospinning machine by subjecting the polymer solution (10% polyvinyl alcohol PVA) loaded with recommended quantities of nutrients under optimal solution (pH, concentration, viscosity) and process (voltage, flow rate, tip-to-collector distance) parameters. The nano-fibres were characterized using SEM, TEM, FT-IR, XRD, TGA and Impedance spectra besides nutrient release pattern by ICP-MS. The data have clearly shown that nano-fibres retained nutrients and released slowly up to 35 days. After the characterization, green gram (Vigna radiata L) seeds were encapsulated with nano-fibres loaded with multi-nutrients and each seed was coated with approximately 20-25 mg of nano-fibres, dibbled into the soil and the physiological, nutritional, growth and yield responses were assessed. Seeds encapsulated with nano-fibres fortified with nutrients (NF) had registered significantly higher crop emergence percentage (C 62%; NF 99.8%), root length (C 12.3; NF 27.1 cm), shoot length (C 28.7; NF 47.7 cm), dry matter production (C 16.2; NF 27.5 g) and grain yield (C 621.6; NF 796.3 kg ha-1). All the parameters measured in nano-fibre encapsulated seeds fortified with 100% of recommended dose of nutrients (NF) were higher than uncoated control (C) seeds but comparable with 100 % conventional fertilizer applied ones (RDF). Such phenomenal increase in growth and yield parameters associated with the extensive surface area of nano-fibres that is capable of retaining and releasing nutrients in a regulated pattern and assist in improving the pulses productivity by achieving balance crop nutrition which alleviating multi-nutrient deficiencies.

Carbon-Based Nanomaterials Decorated Electrospun Nanofibers in Biosensors: A Review

Nanomaterials have revolutionized scientific research due to their exceptional physical and chemical capabilities. Carbon-based nanomaterials such as graphene and its derivates have excellent electrical, optical, thermal, physical, and chemical properties that have made them indispensable in several industries worldwide, including medicine, electronics, and energy. By incorporating carbon-based nanomaterials as nanofillers in electrospun nanofibers (ESNFs), smoother and highly conductive nanofibers can be achieved that possess a large surface area and porosity. This approach provides a superior alternative to traditional materials in the development of improved biosensors. Carbon-based ESNFs, among the most exciting new-generation materials, have many applications, including filtration, pharmaceuticals, biosensors, and membranes. The electrospinning technique is a highly efficient and cost-effective method for producing desired nanofibers compared to other methods. Various types of natural and synthetic organic polymers have been successfully utilized in solution electrospinning to produce nanofibers directly. To create diagnostics devices, various biomolecules like antibodies, enzymes, aptamers, ligands, and even cells can be bound to the surface of nanofibers. Electrospun nanofibers can serve as an immobilization matrix to create a biofunctional surface. Thus, biosensors with desired features can be produced in this way. This study comprehensively reviews biosensors that integrate nanodiamonds, fullerenes, carbon nanotubes, graphene oxide, and carbon dots into electrospun nanofibers.

Construction of a point-of-care electrochemical biosensor for Escherichia coli 16S rRNA analysis based on MoS2 nanoprobes

Foodborne pathogens are harmful to human health because they can contaminate food and induce diseases. To efficiently distinguish and determine foodborne bacteria, an ultrasensitive point-of-care electrochemical biosensor was designed for 16S rRNA detection by coupling a signal amplification strategy with MoS2-based nanoprobes. Gold nanoparticles and thionine co-functionalized molybdenum disulfide (MoS2) nanocomposites (MoS2-Thi-AuNPs) were used to construct nanoprobes, which can efficiently monitor the detection process and amplify the detection signal. In the presence of Escherichia coli (E. coli) 16S rRNA, a classical sandwiched DNA structure was formed on the surface of a hierarchical flower-like gold nanostructure-decorated screen-printed carbon electrode (HFGN-SPCE), generating an obvious electrochemical signal from Thi. Under optimal conditions, this designed electrochemical biosensor showed a wide dynamic range (0-1.0 × 106 fM), low detection limit (2.8 fM), high selectivity and accepted stability for E. coli 16S rRNA detection in ideal buffers. Moreover, this biosensor can efficiently determine 16S rRNA in milk samples and 10 CFU mL-1 bacterial lysate. All experimental results suggested that this biosensor has a promising application in the detection of foodborne pathogens.

Electrospun Nanofibers: Shaping the Future of Controlled and Responsive Drug Delivery

Electrospun nanofibers for drug delivery systems (DDS) introduce a revolutionary means of administering pharmaceuticals, holding promise for both improved drug efficacy and reduced side effects. These biopolymer nanofiber membranes, distinguished by their high surface area-to-volume ratio, biocompatibility, and biodegradability, are ideally suited for pharmaceutical and biomedical applications. One of their standout attributes is the capability to offer the controlled release of the active pharmaceutical ingredient (API), allowing custom-tailored release profiles to address specific diseases and administration routes. Moreover, stimuli-responsive electrospun DDS can adapt to conditions at the drug target, enhancing the precision and selectivity of drug delivery. Such localized API delivery paves the way for superior therapeutic efficiency while diminishing the risk of side effects and systemic toxicity. Electrospun nanofibers can foster better patient compliance and enhanced clinical outcomes by amplifying the therapeutic efficiency of routinely prescribed medications. This review delves into the design principles and techniques central to achieving controlled API release using electrospun membranes. The advanced drug release mechanisms of electrospun DDS highlighted in this review illustrate their versatility and potential to improve the efficacy of medical treatments.

Recent Progress in Stimuli-Responsive Antimicrobial Electrospun Nanofibers

Electrospun nanofibrous membranes have garnered significant attention in antimicrobial applications, owing to their intricate three-dimensional network that confers an interconnected porous structure, high specific surface area, and tunable physicochemical properties, as well as their notable capacity for loading and sustained release of antimicrobial agents. Tailoring polymer or hybrid-based nanofibrous membranes with stimuli-responsive characteristics further enhances their versatility, enabling them to exhibit broad-spectrum or specific activity against diverse microorganisms. In this review, we elucidate the pivotal advancements achieved in the realm of stimuli-responsive antimicrobial electrospun nanofibers operating by light, temperature, pH, humidity, and electric field, among others. We provide a concise introduction to the strategies employed to design smart electrospun nanofibers with antimicrobial properties. The core section of our review spotlights recent progress in electrospun nanofiber-based systems triggered by single- and multi-stimuli. Within each stimulus category, we explore recent examples of nanofibers based on different polymers and antimicrobial agents. Finally, we delve into the constraints and future directions of stimuli-responsive nanofibrous materials, paving the way for their wider application spectrum and catalyzing progress toward industrial utilization.

Nanocellulose-based porous materials: Regulation and pathway to commercialization in regenerative medicine

We review the recent progress that have led to the development of porous materials based on cellulose nanostructures found in plants and other resources. In light of the properties that emerge from the chemistry, shape and structural control, we discuss some of the most promising uses of a plant-based material, nanocellulose, in regenerative medicine. Following a brief discussion about the fundamental aspects of self-assembly of nanocellulose precursors, we review the key strategies needed for material synthesis and to adjust the architecture of the materials (using three-dimensional printing, freeze-casted porous materials, and electrospinning) according to their uses in tissue engineering, artificial organs, controlled drug delivery and wound healing systems, among others. For this purpose, we map the structure-property-function relationships of nanocellulose-based porous materials and examine the course of actions that are required to translate innovation from the laboratory to industry. Such efforts require attention to regulatory aspects and market pull. Finally, the key challenges and opportunities in this nascent field are critically reviewed.

Electrospun nanofiber-based indicatorpaper sensing platform for fluorescence and visualization detection of norfloxacin

Norfloxacin (NOR) residues in water pose a serious threat to human health via the food chain, necessitating the development of a rapid on-site antibiotic detection technique. In this work, we utilize electrostatic spinning technology that combines polyacrylonitrile (PAN) fibers and adenosine triphosphate (ATP)-rare earth metal Tb3+ complexes (ATP/Tb) to construct a new ternary film-based sensor for sensitive, quick, and convenient field testing of NOR in water. The operating mechanism is that the ternary system produces gradually enhanced bright green fluorescence at increasing concentrations of NOR. The unique fluorescence property of the ternary systems is attributed to the use of ATP, rather than the commonly used adenosine monophosphate (AMP), to coordinate with Tb3+, which avoided the possible fluorescence quenching from competitive water binding. Benefiting from the PAN nanofiber's superior stability, acid, and alkali resistance, and flexibility as support, the ternary system exhibited a good linear response to NOR in a wide dynamic range of 0.04-30 μM at the detection limit of 16 nM. Additionally, the combination of a smartphone color recognition app allows for quick on-scene NOR detection. This film sensing strategy is instructive for the development of smart and portable sensing platforms for real-time detection of analytes such as antibiotics, pesticide residues, and hazardous materials in water bodies.

Cryo-Electrospinning Generates Highly Porous Fiber Scaffolds Which Improves Trabecular Meshwork Cell Infiltration

Human trabecular meshwork is a sieve-like tissue with large pores, which plays a vital role in aqueous humor outflow. Dysfunction of this tissue can occur, which leads to glaucoma and permanent vision loss. Replacement of trabecular meshwork with a tissue-engineered device is the ultimate objective. This study aimed to create a biomimetic structure of trabecular meshwork using electrospinning. Conventional electrospinning was compared to cryogenic electrospinning, the latter being an adaptation of conventional electrospinning whereby dry ice is incorporated in the fiber collector system. The dry ice causes ice crystals to form in-between the fibers, increasing the inter-fiber spacing, which is retained following sublimation. Structural characterization demonstrated cryo-scaffolds to have closer recapitulation of the trabecular meshwork, in terms of pore size, porosity, and thickness. The attachment of a healthy, human trabecular meshwork cell line (NTM5) to the scaffold was not influenced by the fabrication method. The main objective was to assess cell infiltration. Cryo-scaffolds supported cell penetration deep within their structure after seven days, whereas cells remained on the outer surface for conventional scaffolds. This study demonstrates the suitability of cryogenic electrospinning for the close recapitulation of trabecular meshwork and its potential as a 3D in vitro model and, in time, a tissue-engineered device.

A Sequential Electrospinning of a Coaxial and Blending Process for Creating Double-Layer Hybrid Films to Sense Glucose

This study presents a glucose biosensor based on electrospun core-sheath nanofibers. Two types of film were fabricated using different electrospinning procedures. Film F1 was composed solely of core-sheath nanofibers fabricated using a modified coaxial electrospinning process. Film F2 was a double-layer hybrid film fabricated through a sequential electrospinning and blending process. The bottom layer of F2 comprised core-sheath nanofibers fabricated using a modified process, in which pure polymethacrylate type A (Eudragit L100) was used as the core section and water-soluble lignin (WSL) and phenol were loaded as the sheath section. The top layer of F2 contained glucose oxidase (GOx) and gold nanoparticles, which were distributed throughout the polyvinylpyrrolidone K90 (PVP K90) nanofibers through a single-fluid blending electrospinning process. The study investigated the sequential electrospinning process in detail. The experimental results demonstrated that the F2 hybrid film had a higher degradation efficiency of β-D-glucose than F1, reaching a maximum of over 70% after 12 h within the concentration range of 10-40 mmol/L. The hybrid film F2 is used for colorimetric sensing of β-D-glucose in the range of 1-15 mmol/L. The solution exhibited a color that deepened gradually with an increase in β-D-glucose concentration. Electrospinning is flexible in creating structures for bio-cascade reactions, and the double-layer hybrid film can provide a simple template for developing other sensing nanomaterials.

Application of Electrospun Water-Soluble Synthetic Polymers for Multifunctional Air Filters and Face Masks

The worsening of air quality is an urgent human health issue of modern society. The outbreak of COVID-19 has made the improvement of air quality even more imperative, both for the general achievement of major health gains and to reduce the critical factors in the transmission of airborne diseases. Thus, the development of solutions for the filtration of airborne pollutants is pivotal. Electrospinning has gained wide attention as an effective fabrication technique for preparing ultrafine fibers which are specifically tailored for air filtration. Nevertheless, the utilization of harmful organic solvents is the major barrier for the large-scale applicability of electrospinning. The use of water-soluble synthetic polymers has attracted increasing attention as a 'green' solution in electrospinning. We reported an overview of the last five years of the scientific literature on the use of water-soluble synthetic polymers for the fabrication of multifunctional air filters layers. Most of recent studies have focused on polyvinyl alcohol (PVA). Various modifications of electrospun polymers have been also described. The use of water-soluble synthetic polymers can contribute to the scalability of electrospinning and pave the way to innovative applications. Further studies will be required to fully harness the potentiality of these 'greener' electrospinning processes.

A Review on Electrospinning as Versatile Supports for Diverse Nanofibers and Their Applications in Environmental Sensing

Rapid industrialization is accompanied by the deterioration of the natural environment. The deepening crisis associated with the ecological environment has garnered widespread attention toward strengthening environmental monitoring and protection. Environmental sensors are one of the key technologies for environmental monitoring, ultimately enabling environmental protection. In recent decades, micro/nanomaterials have been widely studied and applied in environmental sensing owing to their unique dimensional properties. Electrospinning has been developed and adopted as a facile, quick, and effective technology to produce continuous micro- and nanofiber materials. The technology has advanced rapidly and become one of the hotspots in the field of nanomaterials research. Environmental sensors made from electrospun nanofibers possess many advantages, such as having a porous structure and high specific surface area, which effectively improve their performance in environmental sensing. Furthermore, by introducing functional nanomaterials (carbon nanotubes, metal oxides, conjugated polymers, etc.) into electrospun fibers, synergistic effects between different materials can be utilized to improve the catalytic activity and sensitivity of the sensors. In this review, we aimed to outline the progress of research over the past decade on electrospinning nanofibers with different morphologies and functional characteristics in environmental sensors.

Electrospun hybrid nanofibers: Fabrication, characterization, and biomedical applications

Nanotechnology is one of the most promising technologies available today, holding tremendous potential for biomedical and healthcare applications. In this field, there is an increasing interest in the use of polymeric micro/nanofibers for the construction of biomedical structures. Due to its potential applications in various fields like pharmaceutics and biomedicine, the electrospinning process has gained considerable attention for producing nano-sized fibers. Electrospun nanofiber membranes have been used in drug delivery, controlled drug release, regenerative medicine, tissue engineering, biosensing, stent coating, implants, cosmetics, facial masks, and theranostics. Various natural and synthetic polymers have been successfully electrospun into ultrafine fibers. Although biopolymers demonstrate exciting properties such as good biocompatibility, non-toxicity, and biodegradability, they possess poor mechanical properties. Hybrid nanofibers from bio and synthetic nanofibers combine the characteristics of biopolymers with those of synthetic polymers, such as high mechanical strength and stability. In addition, a variety of functional agents, such as nanoparticles and biomolecules, can be incorporated into nanofibers to create multifunctional hybrid nanofibers. Due to the remarkable properties of hybrid nanofibers, the latest research on the unique properties of hybrid nanofibers is highlighted in this study. Moreover, various established hybrid nanofiber fabrication techniques, especially the electrospinning-based methods, as well as emerging strategies for the characterization of hybrid nanofibers, are summarized. Finally, the development and application of electrospun hybrid nanofibers in biomedical applications are discussed.

Electrospun nanofibers fabricated by natural biopolymers for intelligent food packaging

An "intelligent" or smart packaging is able to continuously monitor physicochemical and/or biological variations of packaged food materials, providing real-time information concerning their quality, maturity, and safety. Electrospun nanofiber (ENF) structures, nowadays, reckon as versatile biomaterial platforms in designing intelligent packaging (IP) systems. Natural biopolymer-based ENF traits, for example, surface chemistry, rate of degradation, fiber diameter, and degree of alignment, facilitate the development of unique, tunable IP, enhancing food quality, and safety. In this review, after a brief overview of the electrospinning process, we review food IP systems, which can be utilized to detect variations in food features, for example, those based on alterations in temperature, O2 level, time, humidity, pH, or microbial contamination. Different intelligent approaches that are applicable in engineering IP materials are then highlighted, that is, indicators, data carriers, and sensors. The latest research on the application of ENFs made with natural biopolymers in food IP and their performance on different packaged food types (i.e. meat, fruits and vegetables, dairy products, etc.) are underlined. Finally, the challenges and outlook of these systems in the food industry are discussed.

Graphene Incorporated Electrospun Nanofiber for Electrochemical Sensing and Biomedical Applications: A Critical Review

The extraordinary material graphene arrived in the fields of engineering and science to instigate a material revolution in 2004. Graphene has promptly risen as the super star due to its outstanding properties. Graphene is an allotrope of carbon and is made up of sp²-bonded carbon atoms placed in a two-dimensional honeycomb lattice. Graphite consists of stacked layers of graphene. Due to the distinctive structural features as well as excellent physico-chemical and electrical conductivity, graphene allows remarkable improvement in the performance of electrospun nanofibers (NFs), which results in the enhancement of promising applications in NF-based sensor and biomedical technologies. Electrospinning is an easy, economical, and versatile technology depending on electrostatic repulsion between the surface charges to generate fibers from the extensive list of polymeric and ceramic materials with diameters down to a few nanometers. NFs have emerged as important and attractive platform with outstanding properties for biosensing and biomedical applications, because of their excellent functional features, that include high porosity, high surface area to volume ratio, high catalytic and charge transfer, much better electrical conductivity, controllable nanofiber mat configuration, biocompatibility, and bioresorbability. The inclusion of graphene nanomaterials (GNMs) into NFs is highly desirable. Pre-processing techniques and post-processing techniques to incorporate GNMs into electrospun polymer NFs are precisely discussed. The accomplishment and the utilization of NFs containing GNMs in the electrochemical biosensing pathway for the detection of a broad range biological analytes are discussed. Graphene oxide (GO) has great importance and potential in the biomedical field and can imitate the composition of the extracellular matrix. The oxygen-rich GO is hydrophilic in nature and easily disperses in water, and assists in cell growth, drug delivery, and antimicrobial properties of electrospun nanofiber matrices. NFs containing GO for tissue engineering, drug and gene delivery, wound healing applications, and medical equipment are discussed. NFs containing GO have importance in biomedical applications, which include engineered cardiac patches, instrument coatings, and triboelectric nanogenerators (TENGs) for motion sensing applications. This review deals with graphene-based nanomaterials (GNMs) such as GO incorporated electrospun polymeric NFs for biosensing and biomedical applications, that can bridge the gap between the laboratory facility and industry.

Green Chemistry for Biomimetic Materials: Synthesis and Electrospinning of High-Molecular-Weight Polycarbonate-Based Nonisocyanate Polyurethanes

Conventional synthesis routes for thermoplastic polyurethanes (TPUs) still require the use of isocyanates and tin-based catalysts, which pose considerable safety and environmental hazards. To reduce both the ecological footprint and human health dangers for nonwoven TPU scaffolds, it is key to establish a green synthesis route, which eliminates the use of these toxic compounds and results in biocompatible TPUs with facile processability. In this study, we developed high-molecular-weight nonisocyanate polyurethanes (NIPUs) through transurethanization of 1,6-hexanedicarbamate with polycarbonate diols (PCDLs). Various molecular weights of PCDL were employed to maximize the molecular weight of NIPUs and consequently facilitate their electrospinnability. The synthesized NIPUs were characterized by nuclear magnetic resonance, Fourier-transform infrared spectroscopy, gel permeation chromatography, and differential scanning calorimetry. The highest achieved molecular weight (M _w) was 58,600 g/mol. The NIPUs were consecutively electrospun into fibrous scaffolds with fiber diameters in the submicron range, as shown by scanning electron microscopy (SEM). To assess the suitability of electrospun NIPU mats as a possible biomimetic load-bearing pericardial substitute in cardiac tissue engineering, their cytotoxicity was investigated in vitro using primary human fibroblasts and a human epithelial cell line. The bare NIPU mats did not need further biofunctionalization to enhance cell adhesion, as it was not outperformed by collagen-functionalized NIPU mats and hence showed that the NIPU mats possess a great potential for use in biomimetic scaffolds.

Antimutagenic and Antiproliferative Activity of the Coccoloba uvifera L. Extract Loaded in Nanofibers of Gelatin/Agave Fructans Elaborated by Electrospinning

BACKGROUND

The Coccoloba uvifera L. species is currently considered an important source of compounds of high biological value such as lupeol, this is related to different biological activities of importance to human health.

OBJECTIVE

The objective of this study was to encapsulate the C. uvifera extract in nanofibers made with the biopolymers gelatin (G)/high-grade polymerization agave fructans (HDPAF) in the proportions 1:0, 1:1, 1:2, 1:3 and 0:1, through the electrospinning process, in addition to evaluating the antimutagenic and antiproliferative properties of the encapsulated extract.

METHOD

The physicochemical characteristics of the nanofibers were evaluated, as well as the antiproliferative and antimutagenic activities of the encapsulated and unencapsulated extract. SEM evaluation shows nanofibers of smooth, continuous morphology and nanometric size (50-250 nm). The TGA, FTIR-ATR, HPLC-MS analyzes reveal the presence of the extract in the nanofibers.

RESULTS

The extract did not show a mutagenic effect during the development of the Ames test, on the other hand, the MTT test showed the antiproliferative effect at the concentrations of 50 and 100 µg/mL of extract.

CONCLUSION

the extract of C. uvifera loaded in nanofibers elaborated by electrospinning with the G/HDPAF biopolymers, conserves its antimutagenic and antiproliferative properties.

Bio-nano-composites containing at least two components, chitosan and zein, for food packaging applications: A review of the nano-composites in comparison with the conventional counterparts

Both chitosan and zein are safe industrial biopolymers for the 21St century, respecting environmentally concerns. This review mainly is focused on preparations, properties and applications of a promising food packaging material, chitosan-zein nano-composite (NC). The properties and applications of the NCs were compared with their conventional counterparts. The structure of chitosan- zein composites was proposed. A procedure for preparations of conventional and nano zein-chitosan composites was proposed. The sizes of composites depend on molecular weight of chitosan and zein, the ratio of chitosan/zein, and pH of chitosan-zein solutions. The NCs had superior mechanical, antimicrobial, antioxidant, and barrier properties compared with the conventional ones. The properties of the composites were further improved by introduction of bioactive compounds, fillers or plasticizers. The composites have potential to employ as coatings/packaging materials to protect mushroom, meats, and fresh fruits and vegetables.

Electrospun Nanofibers: Current Progress and Applications in Food Systems

Electrospinning has the advantages of simple manufacturing equipment, a low spinning cost, wide range of spinnable materials, and a controllable mild process, which can continuously fabricate submicron or nanoscale ultrafine polymer fibers without high temperature or high pressure. The obtained nanofibrous films may have a large specific surface area, unique pore structure, and easy-to-modify surface characteristics. This review briefly introduces the types and fiber structures of electrospinning and summarizes the applications of electrospinning for food production (e.g., delivery systems for functional food, filtration of beverages), food packaging (e.g., intelligent packaging, antibacterial packaging, antioxidant packaging), and food analysis (e.g., pathogen detection, antibiotic detection, pesticide residue detection, food compositions analysis), focusing on the advantages of electrospinning applications in food systems. Furthermore, the limitations and future research directions of the technique are discussed.

Fabrication of stable electrospun blended chitosan-poly(vinyl alcohol) nanofibers for designing naked-eye colorimetric glucose biosensor based on GOx/HRP

In this study, designing of a stable electrospun blended chitosan (CS)-poly(vinyl alcohol) (PVA) nanofibers for colorimetric glucose biosensing in an aqueous medium was investigated. CS and PVA solutions were blended to acquire an optimum content (CS/PVA:1/4) and electrospunned to obtain uniform and bead-free CS/PVA nanofiber structures following the optimization of the electrospinning parameters (33 kV, 20 cm, and 1.2 ml.h^-1). Crosslinking process applied subsequently provided mechanically and chemically stable nanofibers with an average diameter of 378 nm. The morphological homogeneity, high fluid absorption ability (>%50), thermal (<230 °C) and morphological stability, surface hydrophilicity and degrability properties of cross-linked CS/PVA nanofiber demonstrated their great potential to be developed as an eye-readable strip for biosensing applications. The glucose oxidase (GOx) and horseradish peroxidase (HRP) was immobilized by physical adsorption on the cross-linked CS/PVA nanofiber. The glucose assay analysis by ultraviolet-visible (UV-Vis) spectrophotometry using the same enzymatic system of the proposed glucose strips in form of absorbance versus concentration plot was found to be linear over a glucose concentration range of 2.7 to 13.8 mM. The prepared naked eye colorimetric glucose detection strips, with lower detection limit of 2.7 mM, demonstrated dramatic color change from white (0 mM) to brownish-orange (13.8 mM). The developed cross-linked CS/PVA nanofiber strips, prepared by electrospinnig procedure, could be easily adapted to a color map, as an alternative material for glucose sensing. Design of a practical, low-cost, and environmental-friendly bio-based CS/PVA testing strips for eye readable detection were presented and suggested as an applicable medium for a wide range of glucose concentrations.

Physical and biological properties of electrospun poly(d,l-lactide)/nanoclay and poly(d,l-lactide)/nanosilica nanofibrous scaffold for bone tissue engineering

Electrospun scaffolds exhibiting high physical performances with the ability to support cell attachment and proliferation are attracting more and more scientific interest for tissue engineering applications. The inclusion of inorganic nanoparticles such as nanosilica and nanoclay into electrospun biopolymeric matrices can meet these challenging requirements. The silica and clay incorporation into polymeric nanofibers has been reported to enhance and improve the mechanical properties as well as the osteogenic properties of the scaffolds. In this work, for the first time, the physical and biological properties of polylactic acid (PLA) electrospun mats filled with different concentrations of nanosilica and nanoclay were evaluated and compared. The inclusion of the particles was evaluated through morphological investigations and Fourier transform infrared spectroscopy. The morphology of nanofibers was differently affected by the amount and kind of fillers and it was correlated to the viscosity of the polymeric suspensions. The wettability of the scaffolds, evaluated through wet contact angle measurements, slightly increased for both the nanocomposites. The crystallinity of the systems was investigated by differential scanning calorimetry highlighting the nucleating action of both nanosilica and nanoclay on PLA. Scaffolds were mechanically characterized with tensile tests to evaluate the reinforcing action of the fillers. Finally, cell culture assays with pre-osteoblastic cells were conducted on a selected composite scaffold in order to compare the cell proliferation and morphology with that of neat PLA scaffolds. Based on the results, we can convince that nanosilica and nanoclay can be both considered great potential fillers for electrospun systems engineered for bone tissue regeneration.

The Food-Materials Nexus: Next Generation Bioplastics and Advanced Materials from Agri-Food Residues

The most recent strategies available for upcycling agri-food losses and waste (FLW) into functional bioplastics and advanced materials are reviewed and the valorization of food residuals are put in perspective, adding to the water-food-energy nexus. Low value or underutilized biomass, biocolloids, water-soluble biopolymers, polymerizable monomers, and nutrients are introduced as feasible building blocks for biotechnological conversion into bioplastics. The latter are demonstrated for their incorporation in multifunctional packaging, biomedical devices, sensors, actuators, and energy conversion and storage devices, contributing to the valorization efforts within the future circular bioeconomy. Strategies are introduced to effectively synthesize, deconstruct and reassemble or engineer FLW-derived monomeric, polymeric, and colloidal building blocks. Multifunctional bioplastics are introduced considering the structural, chemical, physical as well as the accessibility of FLW precursors. Processing techniques are analyzed within the fields of polymer chemistry and physics. The prospects of FLW streams and biomass surplus, considering their availability, interactions with water and thermal stability, are critically discussed in a near-future scenario that is expected to lead to next-generation bioplastics and advanced materials.

Exploring the impact of calcination parameters on the crystal structure, morphology, and optical properties of electrospun Fe2TiO5 nanofibers

Nanostructured Fe₂TiO₅ (pseudobrookite), a mixed metal oxide material holds significant promise for utilization in energy and environmental applications. However, its full application is still hindered due to the difficulty to synthesize monophasic Fe₂TiO₅ with high crystallinity and a large specific surface area. Herein, Fe₂TiO₅ nanofibers were synthesized via a versatile and low-cost electrospinning method, followed by a calcination process at different temperatures. We found a significant effect of the calcination process and its duration on the crystalline phase in the form of either pseudobrookite or pseudobrookite–hematite–rutile and the morphology of calcined nanofibers. The crystallite size increased whereas the specific surface area decreased with an increase in calcination temperature. At higher temperatures, the growth of Fe₂TiO₅ nanoparticles and simultaneous coalescence of small particles was noted. The highest specific surface area was obtained for the sample calcined at 500 °C for 6 h (S_BET = 64.4 m² g⁻¹). This work opens new opportunities in the synthesis of Fe₂TiO₅ nanostructures using the electrospinning method and a subsequent optimized calcination process for energy-related applications.

Nanostructured Fe₂TiO₅ (pseudobrookite), a mixed metal oxide material holds significant promise for utilization in energy and environmental applications.

Graphene Quantum Dots-Based Nanocomposites Applied in Electrochemical Sensors: A Recent Survey

Graphene quantum dots (GQDs) have been widely investigated in recent years due to their outstanding physicochemical properties. Their remarkable characteristics allied to their capability of being easily synthesized and combined with other materials have allowed their use as electrochemical sensing platforms. In this work, we survey recent applications of GQDs-based nanocomposites in electrochemical sensors and biosensors. Firstly, the main characteristics and synthesis methods of GQDs are addressed. Next, the strategies generally used to obtain the GQDs nanocomposites are discussed. Emphasis is given on the applications of GQDs combined with distinct 0D, 1D, 2D nanomaterials, metal-organic frameworks (MOFs), molecularly imprinted polymers (MIPs), ionic liquids, as well as other types of materials, in varied electrochemical sensors and biosensors for detecting analytes of environmental, medical, and agricultural interest. We also discuss the current trends and challenges towards real applications of GQDs in electrochemical sensors.

Morphological, Thermal, and Mechanical Properties of Electrospun Recycled Poly(ethylene terephthalate)/Graphene Oxide Composite Nanofiber Membranes

This study investigates the influence of graphene oxide (GO) on the properties of electrospun recycled poly(ethylene terephthalate) (rPET) composite nanofiber membranes. GO nanosheet layers, with good hydrophilic properties, were incorporated at various loadings (0-8 wt %) during electrospinning. The surface morphological analysis revealed that GO loadings of less than 0.5 wt % lead to smoother fiber surfaces due to less agglomeration, as shown by the scanning electron microscope images. The smooth fiber surface shows that the nanosheets are intact within the rPET polymer matrix at low GO loadings. The differential scanning calorimetry results reveal that nucleation increases linearly with GO content as observed by the change in crystallization peak temperature (T _c) of rPET from 184 to 200 °C. Both the T _c and characteristic rPET crystallization peak in the X-ray diffraction pattern indicate the presence of a physical interaction between the GO sheets and the rPET polymer matrix. A decrease of up to 10° in the water contact angle at 0.5 wt % GO loading; beyond this, it starts to increase due to the agglomeration of GO sheets. From this study, it is preferable to maintain the GO content to a maximum of 0.5 wt % to maximize hydrophilicity. This has the implication of enhanced filtration permeation flux in applications where hydrophilic membranes are desired.

Engineered tyrosinases with broadened bio-catalysis scope: immobilization using nanocarriers and applications

Enzyme immobilization is a widely used technology for creating more stable, active, and reusable biocatalysts. The immobilization process also improves the enzyme's operating efficiency in industrial applications. Various support matrices have been designed and developed to enhance the biocatalytic efficiency of immobilized enzymes. Given their unique physicochemical attributes, including substantial surface area, rigidity, semi-conductivity, high enzyme loading, hyper catalytic activity, and size-assisted optical properties, nanomaterials have emerged as fascinating matrices for enzyme immobilization. Tyrosinase is a copper-containing monooxygenase that catalyzes the o-hydroxylation of monophenols to catechols and o-quinones. This enzyme possesses a wide range of uses in the medical, biotechnological, and food sectors. This article summarizes an array of nanostructured materials as carrier matrices for tyrosinase immobilization. Following a detailed background overview, various nanomaterials, as immobilization support matrices, including carbon nanotubes (CNTs), carbon dots (CDs), carbon black (CB), nanofibers, Graphene nanocomposite, platinum nanoparticles, nano-sized magnetic particles, lignin nanoparticles, layered double hydroxide (LDH) nanomaterials, gold nanoparticles (AuNPs), and zinc oxide nanoparticles have been discussed. Next, applied perspectives have been spotlights with particular reference to environmental pollutant sensing, phenolic compounds detection, pharmaceutical, and food industry (e.g., cereal processing, dairy processing, and meat processing), along with other miscellaneous applications.

A Review on the Role and Performance of Cellulose Nanomaterials in Sensors

Sensors and biosensors play a key role as an analytical tool for the rapid, reliable, and early diagnosis of human diseases. Such devices can also be employed for monitoring environmental pollutants in air and water in an expedited way. More recently, nanomaterials have been proposed as an alternative in sensor fabrication to achieve gains in performance in terms of sensitivity, selectivity, and portability. In this direction, the use of cellulose nanomaterials (CNM), such as cellulose nanofibrils (CNF), cellulose nanocrystals (CNC), and bacterial cellulose (BC), has experienced rapid growth in the fabrication of varied types of sensors. The advantageous properties are related to the supramolecular structures that form the distinct CNM, their biocompatibility, and highly reactive functional groups that enable surface functionalization. The CNM can be applied as hydrogels and xerogels, thin films, nanopapers and other structures interesting for sensor design. Besides, CNM can be combined with other materials (e.g., nanoparticles, enzymes, carbon nanomaterials, etc.) and varied substrates to advanced sensors and biosensors fabrication. This review explores recent advances on CNM and composites applied in the fabrication of optical, electrical, electrochemical, and piezoelectric sensors for detecting analytes ranging from environmental pollutants to human physiological parameters. Emphasis is given to how cellulose nanomaterials can contribute to enhance the performance of varied sensors as well as expand novel sensing applications, which could not be easily achieved using standard materials. Finally, challenges and future trends on the use of cellulose-based materials in sensors and biosensors are also discussed.

Catalytic and Photocatalytic Electrospun Nanofibers for Hydrogen Generation from Ammonia Borane Complex: A Review

Hydrogen (H₂) is a promising renewable energy source that can replace fossil fuels since it can solve several environmental and economic issues. However, the widespread usage of H₂ is constrained by its storage and safety issues. Many researchers consider solid materials with an excellent capacity for H₂ storage and generation as the solution for most H₂-related issues. Among solid materials, ammonia borane (abbreviated hereafter as AB) is considered one of the best hydrogen storage materials due to its extraordinary H₂ content and small density. However, the process must be conducted in the presence of efficient catalysts to obtain a reasonable amount of generated H₂. Electrospun nanofibrous catalysts are a new class of efficient catalysts that involves the usage of polymers. Here, a comprehensive review of the ceramic-supported electrospun NF catalysts for AB hydrolysis is presented, with a special focus on catalytic and photolytic performance and preparation steps. Photocatalytic AB hydrolysis was discussed in detail due to its importance and promising results. AB photocatalytic hydrolysis mechanisms under light were also explained. Electrospun catalysts show excellent activity for AB hydrolysis with good recyclability. Kinetics studies show that the AB hydrolysis reaction is independent of AB concentration and the first-order reaction of NF catalysts.

High Performance Mixed-Matrix Electrospun Membranes for Ammonium Removal from Wastewaters

Mixed-matrix electrospun membranes were developed to investigate ammonium removal from low ammonium concentration wastewaters for the first time. Particles derived from the inexpensive zeolite 13X were successfully incorporated into polyethersulfone (PES) matrices. The fabricated mixed-matrix electrospun membranes demonstrate high ammonium removal capacity reaching over 55 mg/g_zeolite, more than 2.5 times higher than the previously fabricated mixed-matrix membranes via non-solvent induced phase inversion. Moreover, the membranes fabricated exhibit high permeability and ease of regeneration. Over 90% of total ammonium nitrogen (TAN) can be removed from low TAN wastewaters such as aquaculture wastewaters. In addition to zeolite 13X, other zeolite particles including zeolite Y, zeolite 3A and 4A were also incorporated into the membrane matrix. The inexpensive zeolite 13X show the highest ammonium exchange capacity. Particle type, loading and the level of its dispersion all affect TAN removal capacity.

In Situ Photopolymerization of Acrylamide Hydrogel to Coat Cellulose Acetate Nanofibers for Drug Delivery System

In this study we developed electrospun cellulose acetate nanofibers (CANFs) that were loaded with a model non-steroidal anti-inflammatory drug (NSAID) (ibuprofen, Ib) and coated with poly(acrylamide) (poly-AAm) hydrogel polymer using two consecutive steps: an electrospinning process followed by photopolymerization of AAm. Coated and non-coated CANF formulations were characterized by several microscopic and spectroscopic techniques to evaluate their physicochemical properties. An analysis of the kinetic release profile of Ib showed noticeable differences due to the presence or absence of the poly-AAm hydrogel polymer. Poly-AAm coating facilitated a constant release rate of drug as opposed to a more conventional burst release. The non-coated CANFs showed low cumulative drug release concentrations (ca. 35 and 83% at 5 and 10% loading, respectively). Conversely, poly-AAm coated CANFs were found to promote the release of drug (ca. 84 and 99.8% at 5 and 10% loading, respectively). Finally, the CANFs were found to be superbly cytocompatible.

Composite Poly(vinyl alcohol)-Based Nanofibers Embedding Differently-Shaped Gold Nanoparticles: Preparation and Characterization

Poly(vinyl alcohol) nanofibrous mats containing ad hoc synthesized gold nanostructures were prepared via a single-step electrospinning procedure and investigated as a novel composite platform with several potential applications. Specifically, the effect of differently shaped and sized gold nanostructures on the resulting mat physical-chemical properties was investigated. In detail, nearly spherical nanoparticles and nanorods were first synthesized through a chemical reduction of gold precursors in water by using (hexadecyl)trimethylammonium bromide as the stabilizing agent. These nanostructures were then dispersed in poly(vinyl alcohol) aqueous solutions to prepare nanofibrous mats, which were then stabilized via a humble thermal treatment able to enhance their thermal stability and water resistance. Remarkably, the nanostructure type was proven to influence the mesh morphology, with the small spherical nanoparticles and the large nanorods leading to thinner well defined or bigger defect-rich nanofibers, respectively. Finally, the good mechanical properties shown by the prepared composite mats suggest their ease of handleability thereby opening new perspective applications.