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Nanoscience & Nanotechnology
Electrospinning is a versatile and scalable fabrication technique that is used to produce nanoscale fibers with diameters ranging from a few nanometers up to micrometers. In a typical electrospinning process, a high voltage is applied to a polymer solution or melt loaded in a syringe. When the electrical forces overcome the surface tension of the liquid or melt, a charged jet is ejected from the tip of the syringe. As the jet travels in the air, one of two things can occur. For techniques using a polymer solution, the solvent evaporates as the jet travels, leaving behind thin solid fibers. For melt electrospinning or other solvent-free techniques, the polymer jet undergoes solidification as it travels, without any solvent evaporation involved. In both cases, the solidified fibers are then deposited on the collector. The key differences are whether solvent evaporation plays a role (for solution electrospinning) or if only solidification occurs without solvents (for melt electrospinning).
- green electrospinning
- biopolymers
- nanofibers
- tissue engineering
- drug delivery
- biosensing
- environmental remediation
- controlled release
- cell
1. Applications in Biotechnology
1.1. Biosensors
Enzyme Immobilization
Green electrospinning produces nanofiber-based biosensors through enzyme immobilization. Cellulose and chitosan fibers entrap glucose oxidase and cholesterol oxidase, respectively, for detection. Nanoscale templating preserves enzyme activity through mild processing. Fibre geometry and reactive surface functionalities such as amine/carboxylate groups covalently tether biomolecules [126,127,128,129,130]. Enzyme-embedded conductive composite fibers electrically translate biological recognition into quantifiable signals. Applications include point-of-care testing and food analyses. Renewable materials avoid petrochemically derived sensor substrates, offering sustainable alternatives. Future work optimizing enzyme loadings and electrical conductivity would achieve faster, lower-cost diagnoses [131,132,133,134,135]. Core-shell and 3D nanostructure designs that spatially separate recognition/transmission elements present new detection mechanisms. Overall, these green sensing platforms demonstrate biocompatible, biodegradable matrices for developing applications in bioprocess monitoring and analytical biotechnology.
Immunosensors
Green electrospun nanofibers develop immunosensor platforms by functionalizing fibre surfaces. Collagen fibers immobilize capture antibodies through coordination bonds with secondary antibodies, facilitating analyte detection via antigen–antibody interactions. Sensitive, renewable gelatin/chitosan composites coprint antibodies and interdigitated electrodes onto a single substrate. Functionalized surfaces concentrate specific molecule recognition for amplified signals transduced electrically [136,137,138,139,140,141]. Applications involve disease diagnostics and food/water safety testing more quickly/affordably than laboratory techniques. Biopolymer surfaces stabilize fragile biomolecules while allowing molecular access. Future work may develop multiplexed detection of pathogen/toxin panels or optimization of the Optifin Reader for future personalized rapid diagnostics [142,143,144,145,146,147]. Overall, these green recognition interfaces coupled with miniaturized electronics offer biocompatible, integrated immunosensor systems for applications in point-of-care testing through portable device formats.
Cell Growth Substrates
Green electrospun nanofibers act as cell culture supports, controlling the microenvironment. Gelatin scaffolds with diverse fibre sizes/densities influence cell morphology, proliferation and differentiation signals. Amine-functionalized polyvinyl alcohol nanofibers covalently link cell adhesive peptides to interact with integrin receptors and modulate behavior. The 3D nanotopographies better mimic in vivo conditions compared to standard tissue culture plates. Applications involve constructing functional tissues such as skin and bone from expanded cell populations on renewable surfaces. Biodegradability allows recycling cell-seeded constructs as implantable scaffolds. Future work optimizing material-specific cues and developing complex 3D constructs could advance organ-on-a-chip platforms for more predictive toxicity/efficacy modelling [148,149,150]. Overall, tunable green electrospun substrates deliver customizable microenvironments, improving basic research methods through naturally derived engineered tissues.
Tissue Modelling
Green electrospun nanostructures aid in the construction of tissue models recreating organ architecture in vitro. Multilayered gelatin–collagen stacks incorporate combinations of endothelial cells, fibroblasts and keratinocytes on adjacent fibre sheets to emulate skin tissue barriers. Placed between fluid chambers, layered open-pore nanofiber membranes model intestinal microenvironments by culturing gut and blood endothelial populations on opposite surfaces. Biomimetic 3D topographies and tissue-selective cell seeding using renewable materials better simulate in vivo complex tissue interfaces than standard 2D cocultures [151,152,153,154,155,156]. Applications involve developing organ models for drug testing and regenerative therapies. Biodegradability facilitates downstream scaffold and implant development using tissue-engineered constructs. Future work may refine tissue structure fidelity and incorporate multiple cell and fluidic interaction dynamics for advanced organ and whole body-on-a-chip platforms. In summary, these controlled 3D tissue models advance disease and toxicology studies, replacing animal testing.
2. Environmental Remediation
2.1. Water Purification
Green electrospun nanofiber membranes enable contaminated water treatment through adsorption and filtration. Cellulose nanofiber mats effectively absorb pollutants such as dyes and heavy metals from wastewater via their high surface area and reactive hydroxyl groups. Composite chitosan–gellan gum nanowebs functionalized with metal-chelating groups capture specific toxic ions during filtration. High porosity maintains throughput without the application of renewable biomass and provides an eco-friendly alternative to petroleum-based purification methods [157,158,159,160]. Future work optimizing membrane thickness and multilayer designs could realize real-world applications addressing challenges such as desalination or industrial effluent remediation. In-line sensor integration would offer automated filtration monitoring as well [161,162,163,164,165]. Overall, these sustainable nanofibrous platforms present a green solution for water purification applications through nanomaterial-enabled adsorptive and sieving mechanisms.
2.2. Air Filters
Green electrospun nanofibers are effective air filtration media for industrial and medical applications. Nonwoven gelatin/PVA mats coated with antibacterial silver nanoparticles capture airborne pathogens in HVAC systems or hospitals. Loose nanofiber networks allow high flow rates while trapping particles/microbes >100 nm via tortuous diffusion paths. Composite chitosan/cellulose filters chemisorb industrial pollutants such as volatile organics and heavy metals from factory fumes [166,167,168,169,170]. As renewable materials, these filters offer sustainable alternatives to synthetic options such as HEPA filters. Optimizing fibre charges and developing self-cleaning properties may realize real-world industrial stack gas cleaning and sterile lab environments [171,172,173,174,175]. In summary, green electrospun air filters show promise for environmental and occupational applications through renewable, high-efficiency filtration of microbiological and chemical air pollutants.
2.3. Controlled Release Fertilizers/Pesticides
Green electrospinning develops agrochemical carriers that provide sustained nutrient/crop protection. Gelatin/clay composite fibers encapsulate fertilizer salts, releasing them gradually as gelatin degrades. This matches plant uptake over growth cycles. Biopesticide-loaded cellulose nanofibers incorporated as mesh barriers maintain insecticide levels for weeks to deter pests. Precisely metering agrochemicals optimizes yields while minimizing pollution from runoff. Renewable polymers substitute for nonbiodegradable formulations [1,176,177,178,179]. Controlled release also reduces application frequency/amounts applied. Future formulations tailoring release profiles address diverse soil/climate conditions. In summary, these green platforms balance agricultural productivity with environmental sustainability through customized nutrient/substance delivery from degradable fibre networks.
2.4. Food Packaging
Green electrospun nanofibers develop active food packaging with antimicrobial properties. Zinc oxide nanoparticle-loaded polyvinyl alcohol coatings on cellulose fibre substrates inhibit bacterial growth on perishable goods. Electrospun gelatin fibers incorporating grapefruit extract not only kill microbes, but also prevent resuspension through a protective physical network. These properties enhance shelf life through multifunctional antioxidant and antibacterial actions compared to passive storage containers [180,181,182,183,184]. Renewable materials replace conventional plastic packaging. Degradability ensures that materials do not persist in the environment upon disposal. Customization with essential oils tailored for specific produce types could optimize microbial inhibition effects [185,186,187,188]. In summary, green active nanofiber coatings provide a sustainable solution to reduce foodborne illness through natural, biodegradable preservation technologies.
2.5. Cell Encapsulation
Green electrospinning develops cell encapsulation platforms for therapeutic applications. Alginate microcapsules codeliver islet cells within chitosan–gelatin nanofiber coatings. Pore sizes allow metabolic exchange, while barriers prevent immune cell infiltration and transplant rejection. Encapsulation within collagen-HA fibers as cell-interactive hydrogels maintains the viability of encapsulated hepatocytes through innate signaling cues. Mild biomaterials advance cell therapies by preventing immune destruction without pharmaceuticals. Future work optimizing capsule mechanical/mass transport properties using advanced bioinking may scale production for treating diabetes or liver diseases [189,190,191,192]. These renewable encapsulation systems offer biocompatible, localized cell immunoprotection through customizable biomaterial–cell interactions.
2.6. Prodrug Activation
Green electrospun scaffolds integrate synthetic biology for controlled multidrug release. Polyester fibers coencapsulate enzyme-expressing E. coli and inactive prodrug conjugates. At infection sites, bacteria metabolize conjugates, activating drugs in sustained bursts. Conductive mixed-ligand hydrogels localize drug-resistant bacteria and anodes, killing cells through reactive oxygen species while releasing drugs [192,193,194,195,196,197,198]. Such living materials bypass many drug resistance challenges by coupling enzymatic activation with synergistic therapies. Biocompatible materials facilitate implantation of these engineered bacterial systems. Future work optimizing signals and population dynamics may realize advanced in vivo diagnostics and therapeutics. In summary, these platforms demonstrate the potential at the nexus of green materials and synthetic biology for developing personalized prodrug delivery strategies.
2.7. Fiber Diameter in Electrospinning
Fiber diameter is integral to the process and concept of electrospinning itself. Key factors like applied voltage, flow rate, tip-to-collector distance, and polymer properties have direct impacts on the attained diameter. For example, collagen fibers can range from 50 to 500 nm while PLA can achieve diameters from 200 nm up to 5 μm, varying over orders of magnitude simply by tweaking these parameters. This ability to engineer materials down to the nanoscale distinguishes electrospun fibers from those made by conventional microfiber production methods. Replicating naturally occurring dimensions, like collagen fibrils in the 50–500 nm range, is what underpins its biomedical relevance. Most fundamentally, it is the charge-induced bending instabilities imparted to the polymer jet as it travels under an applied electric field that enable the establishment of exceedingly thin fibers. Fiber diameter is thus a direct and defining output of the electrospinning process, governed by the very mechanism enabling diameters to be precisely controlled within the distinctive nanoscale regime. This capacity for genuine nanofiber generation is what endows electrospinning with its unique character and multidimensional application landscape compared to other fiber spinning techniques. In this way, fiber diameter is entirely intrinsic to the technology rather than an extrinsic consideration.
This entry is adapted from the peer-reviewed paper 10.3390/technologies11050150
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