Electrospinning of Cyclodextrin Functional Nanofibers for Drug Delivery Applications

Antimicrobial cyclodextrin-assisted electrospun fibers loaded with carvacrol, citronellol and cinnamic acid for wound healing

This work aimed to explore an alternative to the use of antibiotics for prevention and treatment of wounds infection caused by two common bacterial pathogens Staphylococcus aureus and Pseudomonas aeruginosa. For this purpose, three different essential oil components (EOCs), namely carvacrol, citronellol and cinnamic acid, were loaded into electrospun fibers of poly-ε-caprolactone (PCL) aided by alpha-cyclodextrin (αCD) and hydroxypropyl-β-cyclodextrin (HPβCD). Electrospun-fibers prepared with each EOC and their mixtures were screened for antimicrobial capability and characterized regarding morphological, mechanical, thermal, surface polarity, antibiofilm and antioxidant properties. αCD formed poly(pseudo)rotaxanes with PCL and weakly interacted with EOCs, while HPβCD facilitated EOC encapsulation and formation of homogeneous fibers (500-1000 nm diameter) without beads. PCL/HPβCD fibers with high concentration of EOCs (mainly carvacrol and cinnamic acid) showed strong antibiofilm (>3 log CFU reduction) and antioxidant activity (10-50% DPPH scavenging effects). Different performances were recorded for the EOCs and their mixtures; cinnamic acid migrated to fiber surface and was released faster. Fibers biocompatibility was verified using hemolysis tests and in ovo tissue integration and angiogenesis assays. Overall, HPβCD facilitates complete release of EOCs from the fibers to the aqueous medium, being an environment-friendly and cost-effective strategy for the treatment of infected wounds.

Enrofloxacin Pharmaceutical Formulations through the Polymer-Free Electrospinning of β-Cyclodextrin-oligolactide Derivatives

Enrofloxacin (ENR), a member of the fluoroquinolone class of antibiotics, is widely used in veterinary medicine to treat bacterial infections. Like many antibiotics, ENR has limited water solubility and low bioavailability. To address these challenges, drug formulations using solid dispersions, nanosuspensions, surfactants, cocrystal/salt formation, and inclusion complexes with cyclodextrins may be employed. The approach described herein proposes the development of ENR formulations by co-electrospinning ENR with custom-prepared cyclodextrin-oligolactide (CDLA) derivatives. This method benefits from the high solubility of these derivatives, enabling polymer-free electrospinning. The electrospinning parameters were optimized to incorporate significant amounts of ENR into the CDLA nanofibrous webs, reaching up to 15.6% by weight. The obtained formulations were characterized by FTIR and NMR spectroscopy methods and evaluated for their antibacterial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. This study indicates that the presence of CDLA derivative does not inhibit the antibacterial activity of ENR, recommending these formulations for further development.

Cyclodextrins and their potential applications for delivering vitamins, iron, and iodine for improving micronutrient status

Cyclodextrins (CDs) have been investigated as potential biopolymeric carriers that can form inclusion complexes with numerous bioactive ingredients. The inclusion of micronutrients (e.g. vitamins or minerals) into cyclodextrins can enhance their solubility and provide oxidative or thermal stability. It also enables the formulation of products with extended shelf-life. The designed delivery systems with CDs and their inclusion complexes including electrospun nanofibers, emulsions, liposomes, and hydrogels, show potential in enhancing the solubility and oxidative stability of micronutrients while enabling their controlled and sustained release in applications including food packaging, fortified foods and dietary supplements. Nano or micrometer-sized delivery systems capable of controlling burst release and permeation, or moderating skin hydration have been reported, which can facilitate the formulation of several personal and skin care products for topical or transdermal delivery of micronutrients. This review highlights recent developments in the application of CDs for the delivery of micronutrients, i.e. vitamins, iron, and iodine, which play key roles in the human body, emphasizing their existing and potential applications in the food, pharmaceuticals, and cosmeceuticals industries.

Optimizing the fabrication of electrospun nanofibers of prochlorperazine for enhanced dissolution and permeation properties

Despite being an approved antiemetic for more than five decades, the clinical usefulness of prochlorperazine is limited by its low solubility and inconsistent absorption in the gastrointestinal tract, which presents challenges for nanotherapeutic interventions. Here, we report the preparation of a highly soluble and permeable nanofiber formulation of prochlorperazine using the Quality-by-Design approach. The final nanofiber formulation with drug entrapment of 88.02 ± 1.14 % was obtained at 20.0 kV, with a flow rate of 0.5 ml/h and tip-to-collector distance of 19.9 cm. Physio-mechanical properties, such as thickness (0.42 ± 0.02 mm), pH resistance (7.04 ± 0.08), folding endurance (54 ± 5), and tensile strength (0.244 ± 0.02 N.mm-2), were appropriate for packaging and application to oromucosal surfaces. The content uniformity (93.48-106.63 %) and weight variation (<1.8 mg) of the optimal nanofiber formulation were within the permissible limits prescribed for orodispersible films. Microscopical investigations confirm a randomly deposited and dense network of woven nanofibers with an average diameter of 363 ± 5.66 nm. The drug particles were embedded homogeneously on the fiber in the nanoform (4.27 ± 1.34 nm). The spectral analysis using TEM-EDS shows diffraction peaks of sulfur and chlorine, the elemental constituents of prochlorperazine. The drug was amorphized in the nanofiber formulation, as led by the decline of the crystallinity index from 87.25 % to 7.93 % due to electrostatic destabilization and flash evaporation of the solvent. The enthalpy of fusion values of the drug in the nanofiber mat decreased significantly to 23.6 J/g compared to its pristine form, which exhibits a value of 260.7 J/g. The nanofibers were biocompatible with oral mucosal cells, and there were no signs of mucosal irritation compared to 1 % sodium lauryl sulfate. The fiber mats rapidly disintegrated within <1 s and released ≈91.49 ± 2.1 % of the drug within 2 min, almost 2-fold compared to the commercial Stemetil MD® tablets. Similarly, the cumulative amount of the drug permeated across the unit area of the oromucosal membrane was remarkably high (31.28 ± 1.30 μg) compared to 10.17 ± 1.11 μg and 13.10 ± 1.79 μg from the cast film and drug suspension. Our results revealed these nanofiber formulations have the potential to be fast-dissolving oromucosal delivery systems, which can result in enhanced bioavailability with an early onset of action due to rapid disintegration, dissolution, and permeation.

The synergistic effect of metal ions and amino acids on the fermentation of β-CGTase-producing statin DF257

To meet the growing demand of β-cyclodextrin (CD), innovative approaches are being developed to improve the production of β-CD by β-cyclodextrin glucose-transferase (CGTase). Considering the low production and efficacy of wild-type β-CGTase-producing strains, to obtain the strains suitable for industrial production of β-CGTase, the recombinant engineered bacteria strain DF257 is constructed by transfecting with the plasmid expressing His tagged β-CGTase. The fermentation of β-CGTase-expressing DF257 was optimized in the presence of different metal ions, amino acids, and incubated at a certain temperature and pH condition. The results showed that when Mg2+ and isoleucine were added into the culture medium at 0.5 mM and 0.5 g/L, respectively, the enzyme activity of β-CGTase increased significantly after incubation at 37 °C with the initial pH of 7.5. In addition, the optimal temperature for β-CGTase with the addition of Mg2+ and isoleucine was also determined. The T half of β-CGTase under 50, 55, 60 and 65 °C was 9.5, 8.8, 6.2 and 1.2 h, respectively. Further investigation showed that β-CGTase kept stable under the pH 6.0-10.0, and pH 7.5 was identified as the optimal pH condition of β-CGTase. With the addition of Mg2+ and isoleucine, the kinetic properties of β-CGTase in the cyclization reaction had a similar form with Michaelis equation under 50 °C and pH 7.5, and Vmax, Km, and Kcat was 3.74 mg/mL/min, 3.28 mg/mL, and 31.17/s, respectively. The possible underlying mechanism by which Mg2+ and isoleucine synergistically improved the thermostability of β-CGTase was investigated by the surface hydrophobicity index analysis, Fourier transform infrared spectroscopy and differential scanning calorimetry (DSC) analysis. The results indicated that addition of Mg2+ and isoleucine maintained the spatial structure and enhanced the thermostability of β-CGTase. These findings provided a theoretical basis for realizing the industrialization application of β-CGTase in promoting the generation of β-CD.

Biobran-loaded core/shell nanofibrous scaffold: a promising wound dressing candidate

This research examined the effectiveness of Biobran as a bioactive substance that could potentially improve wound healing. It also looked at how Biobran affects the properties of a nanofibrous scaffold made through coaxial electrospinning. This is the first study exploring the use of Biobran in this context and its interaction with nanofibrous scaffolds. The scaffolds were composed of poly(ε-caprolactone) (PCL) in the shell and various concentrations of Biobran blended with polyvinyl alcohol (PVA) in the core. The properties of the scaffolds were characterized by SEM, TEM, FTIR, XRD, TGA, DSC, stress-strain test, WCA, release test, MTT cytotoxicity assay, wound scratching assay, and the dye exclusion method using trypan blue. The scaffolds loaded with Biobran exhibited a more compact and smooth morphology compared with the scaffold without Biobran. The physical interaction and crystallinity of the polymers in the scaffolds were also affected by Biobran in a concentration-dependent manner. This positively influenced their tensile strength, elongation at break, thermal stability, and hydrophilicity. The porosity, water uptake capacity, and WVTR of the nanofibrous scaffolds are within the optimal ranges for wound healing. The release rate of Biobran, which revealed a biphasic release pattern, decreased with increasing Biobran concentration, resulting in controlled and sustained delivery of Biobran from the nanofiber scaffolds. The cell viability assays showed a dose-dependent effect of Biobran on WISH cells, which might be attributed to the positive effect of Biobran on the physicochemical properties of the nanofibrous scaffolds. These findings suggest that Biobran-loaded core/shell nanofiber scaffolds have a potential application in wound healing as an ideal multifunctional wound dressing.

Development, Characterization, and Burn Wound-Healing Potential of Neomycin-Loaded Clay-Reinforced Nanofibers

Background: Skin wounds affect millions of individuals around the world, and their treatment is expensive. Objective: The purpose of this study was to make neomycin-loaded CG/PVA/PAN (NCPP) nanofibers to improve wound healing. Methods: The NCPP nanofibers were characterized by using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and X-ray diffraction. Drug solubility, dissolution, swelling ratio, erosion, and antibacterial studies were performed. The in vivo wound healing study of nanofibers was performed in a rabbit model and was supported by % age wound closure and histopathology. Results: The results of SEM showed some sort of agglomeration on the surface of fibers, while TGA showed 10% more stability for drug-loaded nanofibers. The drug permeation study indicated that the formulation with 15% PVA showed a controlled release profile of the drug. The NCPP nanofibers had an appreciable water retention capability. The NCPP nanofibers showed appreciable antibacterial activity against Enterococcus faecalis (Gram-positive bacteria) and Klebsiella pneumonia (Gram-negative bacteria). The wound healing study showed the better healing properties of NCPP nanofibers within 15 days. Conclusion: The findings helped us to conclude that the NCPP nanofibers were successfully fabricated and found to have a promising role in infected wound healing.

Cyclodextrin Inclusion Complexes for Improved Drug Bioavailability and Activity: Synthetic and Analytical Aspects

Many active pharmaceutical ingredients show low oral bioavailability due to factors such as poor solubility and physical and chemical instability. The formation of inclusion complexes with cyclodextrins, as well as cyclodextrin-based polymers, nanosponges, and nanofibers, is a valuable tool to improve the oral bioavailability of many drugs. The microencapsulation process modifies key properties of the included drugs including volatility, dissolution rate, bioavailability, and bioactivity. In this context, we present relevant examples of the stabilization of labile drugs through the encapsulation in cyclodextrins. The formation of inclusion complexes with drugs belonging to class IV in the biopharmaceutical classification system as an effective solution to increase their bioavailability is also discussed. The stabilization and improvement in nutraceuticals used as food supplements, which often have low intestinal absorption due to their poor solubility, is also considered. Cyclodextrin-based nanofibers, which are polymer-free and can be generated using environmentally friendly technologies, lead to dramatic bioavailability enhancements. The synthesis of chemically modified cyclodextrins, polymers, and nanosponges based on cyclodextrins is discussed. Analytical techniques that allow the characterization and verification of the formation of true inclusion complexes are also considered, taking into account the differences in the procedures for the formation of inclusion complexes in solution and in the solid state.

Electrospun Nanofiber-Based Drug Carrier to Manage Inflammation

Significance: Nonsteroidal anti-inflammatory drugs (NSAIDs) are one of the most widely prescribed drugs to treat inflammation and related ailments. In recent years, loading these drugs onto nanodevices like nanoparticles, nanofibers, etc. as a drug delivery system has gained momentum due to its desirable properties and advantages. The purpose of this review is to examine the existing research on the potential and novel use of nanofiber-assisted delivery of NSAIDs. Recent Advances: Electrospun nanofibers have recently garnered considerable attention from researchers in a variety of sectors. They have proved to be promising vehicles for drug delivery systems because of their exceptional and favorable features like prolonged drug release, controllable porosity, and high surface area. In this article, various polymers and even combinations of polymers loaded with single or multiple drugs were analyzed to achieve the desired drug release rates (burst, sustained, and biphasic) from the electrospun nanofibers. Critical Issues: The administration of these medications can induce major adverse effects, causing patients discomfort. Thus, encapsulating these drugs within electrospun nanofibers helps to reduce the severity of side effects while also providing additional benefits such as targeted and controlled drug release, reduced toxicity, and long-lasting effects of the drug with lower amounts of administration. Future Directions: This review covers previous research on the delivery of NSAIDs using electrospun nanofibers as the matrix. Also, this study intends to aid in the development of enhanced drug delivery systems for the treatment of inflammation and related issues.

Electrospun Food Polysaccharides Loaded with Bioactive Compounds: Fabrication, Release, and Applications

Food polysaccharides are well acclaimed in the field of delivery systems due to their natural safety, biocompatibility with the human body, and capability of incorporating/releasing various bioactive compounds. Electrospinning, a straightforward atomization technique that has been attracting researchers worldwide, is also versatile for coupling food polysaccharides and bioactive compounds. In this review, several popular food polysaccharides including starch, cyclodextrin, chitosan, alginate, and hyaluronic acid are selected to discuss their basic characteristics, electrospinning conditions, bioactive compound release characteristics, and more. Data revealed that the selected polysaccharides are capable of releasing bioactive compounds from as rapidly as 5 s to as prolonged as 15 days. In addition, a series of frequently studied physical/chemical/biomedical applications utilizing electrospun food polysaccharides with bioactive compounds are also selected and discussed. These promising applications include but are not limited to active packaging with 4-log reduction against E. coli, L. innocua, and S. aureus; removal of 95% of particulate matter (PM) 2.5 and volatile organic compounds (VOCs); heavy metal ion removal; increasing enzyme heat/pH stability; wound healing acceleration and enhanced blood coagulation, etc. The broad potentials of electrospun food polysaccharides loaded with bioactive compounds are demonstrated in this review.

Nanofiber-based sorbents: Current status and applications in extraction methods

Advanced sorbents gradually become a research hotspot on account of the increasing attention paid to environmental problems. Due to the prominent physicochemical features of nanofibers (NFs), such as high porosity, large surface area, favorable interconnectivity, high adsorption capacity, wettability, and the possibility of surface modification using functional groups, these nanostructures are regarded as excellent candidates for extraction applications. Therefore, the research in the field of NFs and their nanocomposites has been increasing in recent years. In the present review, we summarize the most recent studies on NFs-based sorbents focusing on strategies for preparation, characterization, and their unique capabilities as porous sorbents in various sorbent-based extraction methods. Moreover, we further described the performance and selectivity of sorbents to achieve improved extraction efficiency. Finally, some perspectives on the challenges and outlook are provided to aid future investigations related to this topic.

Lactone Stabilized by Crosslinked Cyclodextrin Metal-Organic Frameworks to Improve Local Bioavailability of Topotecan in Lung Cancer

The protection of unstable anticancer molecules and their delivery to lesions are challenging issues in cancer treatment. Topotecan (TPT), a classic cytotoxic drug, is widely used for treating refractory lung cancer. However, the therapeutic effects of TPT are jeopardized by its active lactone form that is intrinsically hydrolyzed in physiological fluids, resulting in low bioavailability. Herein, the TPT-loaded crosslinked cyclodextrin metal-organic framework (TPT@CL-MOF) was engineered to improve the local bioavailability of TPT for the treatment of lung cancer. CL-MOF exhibited the efficient loading (12.3 wt%) of TPT with sustained release characteristics. In particular the formulation offered excellent protection in vitro against hydrolysis and increased the half-life of TPT from approximately 0.93 h to 22.05 h, which can be attributed to the host-guest interaction between cyclodextrin and TPT, as confirmed by molecular docking. The TPT@CL-MOF could effectively kill the cancer cells and inhibit the migration and invasion of B16F10 cells in vitro. Moreover, TPT@CL-MOF was efficiently distributed in the lungs after intravenous administration. In an in vivo study using a B16F10 pulmonary metastatic tumor model, TPT@CL-MOF significantly reduced the number and size of metastatic lung nodules at a reduced low dose by five times, and no noticeable side effects were observed. Therefore, this study provides a possible alternative therapy for the treatment of lung cancer with the camptothecin family drugs or other unstable therapeutically significant molecules.

PDMS/PVDF Electrospinning Membranes for Water-in-Oil Emulsion Separation and UV Protection

With industry development, the separation of oily wastewater is becoming more critical. Inspired by organisms such as lotus leaves, biomimetic superhydrophobic surfaces with micro-nano structures have shown great potential in this regard. In this work, PDMS/PVDF oil-water separation membranes with designed microstructures were prepared by electrospinning technology. The membrane-forming effect of electrospinning with different ratios of PDMS and PVDF was studied. The study found that membranes with high PDMS content were more likely to form microspheres, and PDMS tended to concentrate on the microspheres. The results also showed that the microspheres would bring better hydrophobicity to the membrane. When the ratio of PDMS to PVDF is 1:2, the membrane has a water contact angle of up to 150° and an oil contact angle of 0°. At this ratio, the separation efficiency of the membrane for the water-in-oil emulsion is 98.7%, and it can still maintain more than 98% after ten separation cycles, which is a good candidate for oil-water separation. Furthermore, microspheres enable the membrane to achieve macroscopic uniformity and microscopic phase separation so that the membranes have both good elongation and fracture strength. In addition, the PDMS/PVDF membranes also exhibit excellent UV resistance, and their UV protection factor is greater than 185, making them a potential UV protective material.

Surface Functionalization of Nanofibers: The Multifaceted Approach for Advanced Biomedical Applications

Nanocarriers are gaining significant importance in the modern era of drug delivery. Nanofiber technology is one of the prime paradigms in nanotechnology for various biomedical and theranostic applications. Nanofibers obtained after successful electrospinning subjected to surface functionalized for drug delivery, biomedical, tissue engineering, biosensing, cell imaging and wound dressing application. Surface functionalization entirely changes physicochemical and biological properties of nanofibers. In physicochemical properties, wettability, melting point, glass transition temperature, and initial decomposition temperature significantly change offer several advantageous for nanofibers. Similarly, biological properties include cell adhesion, biocompatibility, and proliferation, also changes by functionalization of nanofibers. Various natural and synthetic materials polymers, metals, carbon materials, functional groups, proteins, and peptides, are currently used for surface modification of nanofibers. Various research studies across the globe demonstrated the usefulness of surface functionalized nanofibers in tissue engineering, wound healing, skin cancers, melanoma, and disease diagnosis. The delivery of drug through surface functionalized nanofibers results in improved permeation and bioavailability of drug which is important for better targeting of disease and therapeutic efficacy. This review provides a comprehensive insight about various techniques of surface functionalization of nanofibers along with its biomedical applications, toxicity assessment and global patent scenario.

Rapid Sublingual Delivery of Piroxicam from Electrospun Cyclodextrin Inclusion Complex Nanofibers

Piroxicam (Px) is a nonsteroidal anti-inflammatory drug (NSAID) used for the treatment of osteoarthritis and rheumatoid arthritis. It is administered orally; however, its poor water solubility causes low loading to the nonconventional drug delivery systems (DDSs), such as electrospun fibers. Furthermore, the rapid dissolution of DDS and fast release of the embedded drugs are crucial for oral delivery of drugs to patients who are unconscious or suffering from dysphagia. In this regard, this study reports the development of rapidly dissolving cyclodextrin (CD)-based inclusion complex (IC) nanofibers by waterborne electrospinning for fast oral delivery of Px. Scanning electron microscopy analysis revealed the formation of bead-free fibers with a mean diameter range of 170-500 nm at various concentrations of Px; increasing the Px loading decreased the fiber diameter. The formation of IC was demonstrated by X-ray diffraction (XRD) analysis by the disappearance of crystalline peaks of Px. Likewise, differential scanning calorimetry (DSC) analysis showed the disappearance of the melting peak of the embedded Px due to IC formation. Both Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA) confirmed the presence of Px within the fibers. ¹H NMR experiments demonstrated Px preservation in the fibers after six months. Px-loaded nanofibers were employed for sublingual drug delivery. To mimic the environment of the mouth, the nanofibers were treated with artificial saliva, which revealed the instant dissolution of the nanofibers. Furthermore, dissolution experiments were performed on the tissues wetted with artificial saliva, where the dissolution of the fibers could be extended to a few seconds, demonstrating the suitability of the materials for sublingual oral drug delivery. Overall, this paper, for the first time, reports the rapid oral delivery of Px from polymer-free CD fibers produced by waterborne electrospinning without the requirement of any carrier polymer and toxic solvent.

Fabrication and Characterization of Antifungal Hydroxypropyl-β-Cyclodextrin/Pyrimethanil Inclusion Compound Nanofibers Based on Electrospinning

Pyrimethanil (PMT) is an anilinopyrimidine bactericide with poor water solubility, which limits its applications. To improve the physical and chemical properties of PMT, hydroxypropyl-β-cyclodextrin/pyrimethanil inclusion compound nanofibers (HPβCD/PMT-IC-NFs) were fabricated via electrospinning. A variety of analytical techniques were used to confirm the formation of the inclusion compound. Scanning electron microscopy image displayed that HPβCD/PMT-IC-NF was homogeneous without particles. Thermogravimetric analysis indicated that the formation of the inclusion compound improved the thermostability of PMT. In addition, the phase solubility test illustrated that the inclusion compound formed by PMT and HPβCD had a stronger water solubility. The antifungal effect test exhibited that HPβCD/PMT-IC-NF had better antifungal properties. The release experiment confirmed that HPβCD/PMT-IC-NF had a sustained-release effect, and the release curve conformed to the first-order kinetic model equation. In short, the fabrication HPβCD/PMT-IC-NF inhibited improved solubility and thermostability of PMT, thus promoting the development of pesticide dosage form to water-based and low-pollution direction.

An overview on electrospinning and its advancement toward hard and soft tissue engineering applications

One of the emerging technologies of the recent times harboring nanotechnology to fabricate nanofibers for various biomedical and environmental applications are electrospinning (nanofiber technology). Their relative ease in use, simplicity, functionality and diversity has surpassed the pitfalls encountered with the conventional method of generating fibers. This review aims to provide an overview of electrospinning, principle, methods, feed materials, and applications toward tissue engineering. To begin with, evolution of electrospinning and its typical apparatus have been briefed. Simultaneously, discussion on the production of nanofibers with diversified feed materials such as polymers, small molecules, colloids, and nanoparticles and its transformation into a powerful technology has been dealt with. Further, highlights on the application of nanofibers in tissue engineering and the commercialized products developed using nanofiber technology have been summed up. With this rapidly emerging technology, there would be a great demand pertaining to scalability and environmental challenge toward tissue engineering applications.

Advances in Electrospun Hybrid Nanofibers for Biomedical Applications

Electrospun hybrid nanofibers, based on functional agents immobilized in polymeric matrix, possess a unique combination of collective properties. These are beneficial for a wide range of applications, which include theranostics, filtration, catalysis, and tissue engineering, among others. The combination of functional agents in a nanofiber matrix offer accessibility to multifunctional nanocompartments with significantly improved mechanical, electrical, and chemical properties, along with better biocompatibility and biodegradability. This review summarizes recent work performed for the fabrication, characterization, and optimization of different hybrid nanofibers containing varieties of functional agents, such as laser ablated inorganic nanoparticles (NPs), which include, for instance, gold nanoparticles (Au NPs) and titanium nitride nanoparticles (TiNPs), perovskites, drugs, growth factors, and smart, inorganic polymers. Biocompatible and biodegradable polymers such as chitosan, cellulose, and polycaprolactone are very promising macromolecules as a nanofiber matrix for immobilizing such functional agents. The assimilation of such polymeric matrices with functional agents that possess wide varieties of characteristics require a modified approach towards electrospinning techniques such as coelectrospinning and template spinning. Additional focus within this review is devoted to the state of the art for the implementations of these approaches as viable options for the achievement of multifunctional hybrid nanofibers. Finally, recent advances and challenges, in particular, mass fabrication and prospects of hybrid nanofibers for tissue engineering and biomedical applications have been summarized.

Biofunctionalized Nanomaterials: Alternative for Encapsulation Process Enhancement

In recent years, interest in the development of nanometric materials with specific characteristics has grown; however, there are few scientific contributions that associate encapsulation methodologies and matrices with the particle objective (metabolic directions, type of administration, biological impact, and biocompatibility). This review focuses on describing the benefits and disadvantages of different techniques for designing custom particles and alternatives for the biofunctionalization nanomaterials regarding the biological impact of a nanomaterial with potential use in foods known as nutraceuticals. The study of optical properties, physicochemical factors, and characteristics such as rheological can predict its stability in the application matrix; however, not only should the characterization of a nanocomposite with applications in food be considered, but also the biological impact that it may present.

Regulated Exogenous/Endogenous Inflammation via "Inner-Outer" Medicated Electrospun Fibers for Promoting Tissue Reconstruction

Regenerative medicine aims to provide solutions for structural and functional recovery in conditions where organs suffer from varying degrees of diseases or injuries. However, the exogenous inflammation triggered by implanted biomaterials and endogenous inflammation caused by some disease or tissue destruction has not been solved properly yet. Herein, a functional "inner-outer" medicated core-shell electrospun fibrous membrane is fabricated with RGD surface modification for exogenous inflammation suppression and puerarin loading in the core for long-term endogenous inflammation inhibition through microsol electrospinning technique. The "outer" RGD significantly increases biocompatibility of fibrous membrane through promoting cell viability, adhesion, and proliferation while the "inner" puerarin suppresses inflammatory gene expression via sustained drug release in vitro. Moreover, in a rat abdominal wall hernia model, the functional fibrous membrane successfully reduces exogenous and endogenous inflammation response and promotes wound healing through collagen deposition, smooth muscle formation, and vascularization. In summary, the functional "inner-outer" medicated fibrous membrane holds a great potential for clinical treatment of diseases that needs tissue reconstruction structurally and functionally accompanied by immunoregulation.

Electrospun Nanofiber Membranes for Air Filtration: A Review

Nanomaterials for air filtration have been studied by researchers for decades. Owing to the advantages of high porosity, small pore size, and good connectivity, nanofiber membranes prepared by electrospinning technology have been considered as an outstanding air-filter candidate. To satisfy the requirements of material functionalization, electrospinning can provide a simple and efficient one-step process to fabricate the complex structures of functional nanofibers such as core-sheath structures, Janus structures, and other multilayered structures. Additionally, as a nanoparticle carrier, electrospun nanofibers can easily achieve antibacterial properties, flame-retardant properties, and the adsorption properties of volatile gases, etc. These simple and effective approaches have benefited from the significate development of electrospun nanofibers for air-filtration applications. In this review, the research progress on electrospun nanofibers as air filters in recent years is summarized. The fabrication methods, filtration performances, advantages, and disadvantages of single-polymer nanofibers, multipolymer composite nanofibers, and nanoparticle-doped hybrid nanofibers are investigated. Finally, the basic principles of air filtration are concluded upon and prospects for the application of complex-structured nanofibers in the field of air filtration are proposed.

Preparation of Polyvinylidene Fluoride–Gold Nanoparticles Electrospinning Nanofiber Membranes

In this work, gold nanoparticles (AuNPs) and curcumin drug were incorporated in polyvinylidene fluoride (PVDF) nanofibers by electrospinning as a novel tissue engineering scaffold in nerve regeneration. The influence of AuNPs on the morphology, crystallinity, and drug release behavior of nanofiber membranes was characterized. A successful composite nanofiber membrane sample was observed by scanning electron microscopy (SEM). The addition of AuNPs showed the improved as well as prolonged cumulative release of the drug. The results indicated that PVDF–AuNPs nanofiber membrane could potentially be applied for nerve regeneration.

Microfluidic spinning of fucoxanthin-loaded nanofibers for enhancing antioxidation and clarification of fruit juice

Fruit juice is one of the most popular drinks, which requires strict processing conditions to ensure its quality, especially to prevent enzymatic browning and turbidity loss. In this work, a new strategy for the preparation of composite nanofibers for juice clarification and anti-browning control was proposed. The strategy used microfluidic spinning to combine Fucoxanthin (Fx), hydroxypropyl-γ-cyclodextrin (HP-γ-CD) and polyvinyl pyrrolidone (PVP) to prepare Fx/HP-γ-CD-PVP (PCF) nanofibers, which not only reflected the excellent antioxidant properties of cyclodextrin-wrapped Fx, but also achieved a more optimized juice clarification agent dosage. Molecular docking technique was used to prove that the stable inclusion complex of Fx and HP-γ-CD could be formed by hydrogen bonding when the molar ratio of Fx to HP-γ-CD was 1 : 2, and the binding energy was as low as -10.23 kcal mol^-1. SEM, XRD, FT-IR and TGA were used to characterize the structure of the composite nanofibers, which showed that the thermal stability and water solubility of the embedded Fx were improved. Further studies showed that the apple juice with PCF nanofibers containing inclusion complexes of Fx and HP-γ-CD at a molar ratio of 1 : 2 (PCF 1 : 2) could significantly improve the DPPH and ABTS radical scavenging activity, and could significantly protect the cell membrane integrity of RAW264.7 cells against H₂O₂ oxidative damage. Finally, the effects of PCF nanofibers on the quality of fresh juice were studied, including clarification experiment and sensory evaluation. The results showed that the dosage of PVP in PCF 1 : 2 was only about 4% of the conventional dosage, and the browning index of fresh juice was significantly reduced with the best clarification. The available data provided in this study would provide a promising safety strategy for the food processing of fresh juice and the extension of its storage life.

Photothermal Activatable Mucoadhesive Fiber Mats for On-Demand Delivery of Insulin via Buccal and Corneal Mucosa

Electrospun fiber mats loaded with therapeutics have gained considerable attention as a versatile tool in the biomedical field. While these bandages are largely based on fast-dissolving polymers to release the cargo, stimuli-responsive fiber mats have the advantages of providing a timely and spatially controlled drug delivery platform, which can be refilled and reused several times. These benefits make electrospun fiber patches original platforms for painless and convenient on-demand hormone release. Because of the high need of more convenient and non-invasive methods for delivering insulin, a hormone that is currently used to treat hundred million people with diabetes worldwide, we have investigated the tremendous potential of reduced graphene oxide modified poly(acrylic acid) based fiber mats as an original platform for buccal and corneal insulin delivery on-demand. The PAA@rGO hydrogel-like fibers rendered water-insoluble by incorporating β-cyclodextrin, followed by thermal cross-linking, which showed adequate tensile strength along with high adsorption capacity of insulin at pH 7 and good recyclability. The fiber mats maintained good fibrous morphology and high loading efficiency even after five loading-release cycles. The mucoadhesive nature of the fibers allowed their application for insulin delivery via the eye cornea and the buccal mouth lining, as evidenced in ex vivo studies. Insulin loaded PAA@rGO hydrogel-like fibers showed an insulin flux via buccal lining of pigs of 16.6 ± 2.9 μg cm^-2 h^-1 and 24.3 ± 3.1 μg cm^-2 h^-1 for porcine cornea. Testing on healthy adult volunteers confirmed the excellent, mucoadhesive nature of the bandage, with three out of six volunteers feeling completely comfortable (note 8.3) while wearing the patches in the buccal cavity.

Development of fast-dissolving dosage forms of curcuminoids by electrospinning for potential tumor therapy application

Curcuminoids (CUs) of antitumor and various other potential biological activities have extremely low water solubility therefore special formulation was elaborated. New fast dissolving reconstitution dosage forms of four CUs were prepared as fibrous form of 2-hydroxypropyl-β-cyclodextin (HP-β-CD). In the electrospinning process HP-β-CD could act both as solubilizer and fiber-forming agent. The solubilization efficiency of the CU-HP-β-CD systems was determined with phase-solubility measurements. The electrospun CUs were amorphous and uniformly distributed in the fibers according to XRD analysis and Raman mappings. The fibrous final products had fast (<5 min) and complete dissolution. In typical iv. infusion reconstitution volume (20 mL) fibers containing 40-80 mg of CU could be dissolved, which is similar to the currently proposed dose (<120 mg/m²). The in vitro cytostatic effect data showed that the antitumor activity of the CU-HP-β-CD complexes was similar or better compared to the free APIs.

A review on remediation technologies using functionalized Cyclodextrin

Modern lifestyle and alleviated anthropogenic activities have increased the pollutant load, ultimately causing stress on the environment. In industrialization, many harmful compounds are released into the environment polluting air, water, and soil, triggering adverse impacts on the ecosystem and human beings. Therefore, the development of advanced remediation technologies turns out as a significant environmental priority. Less polar cyclic oligosaccharide Cyclodextrin (CD) with cavity binding organic compounds attracted attention by helping effectively as environmental application. The formation of inclusion complexes and modified Cyclodextrin by cross-linking or surface modification enhances their capacity to abate pollutant effectively from the environment. Modification results in the formation of several novel materials such as CD-based composites, nanocomposites, crosslinked polymer or hydrogels, potent cross-linkers, CD-based membranes, and CD immobilized supports. Several environmental remediation technologies based on Cyclodextrin and modified Cyclodextrin have been discussed in detail in this review. Various environmental applications of Cyclodextrin and its derivatives have been discussed, along with their formation, properties, and characterization. Effective removal of organic pollutants, inorganic pollutants, micropollutants, volatile compounds etc., has been explained using several remediation technologies. Based on CD innocuity, this is referred to as the green process. The reversible equilibrium corresponded by the inclusion phenomenon sets a significant trend in the field of CD environmental application to develop techniques by incorporating supramolecular chemistry as well as irreversible methods such as biodegradation and advanced oxidation. It helps in the complete removal of pollutants and ultimately recycling the CD.

Modification of cyclodextrin and use in environmental applications

Water pollution, which has become a global problem in parallel with environmental pollution, is a problem that needs to be solved urgently, considering the gradual depletion of water resources. The inadequacy of the water treatment methods and the materials used somehow directed the researchers to look for dual character structures such as biocompatible and biodegradable β-cyclodextrin (β-CD). β-CD, which is normally insoluble in water, is used in demanding wastewater applications by being modified with the help of different agents to be water soluble or transformed into polymeric adsorbents as a result of co-polymerization via cross-linkers. In this way, in addition to the host-guest interactions offered by β-CD, secondary forces arising from these interactions provide advantages in terms of regeneration and reusability. However, the adsorption efficiency and synthesis steps need to be improved. Based on the current studies presented in this review, in which cross-linkers and modification methods are also mentioned, suggestions for novel synthesis methods of new-generation β-CD-based materials, criticisms, and recent methods of removal of micropollutants such as heavy metals, industrial dyes, harmful biomolecules, and pharmaceutics wastes are mentioned.

Comparing Antibiotic Pastes with Electrospun Nanofibers as Modern Drug Delivery Systems for Regenerative Endodontics

Nanomaterials have various features that make these types of materials able to be applied in different biomedical applications like, diagnosis, treatment, and drug delivery. Using such materials in endodontic filed both to face the challenges that occur during treatment processes and to make these materials have an antibacterial effect without showing any harm on the host cells. The approach of nanofibers loaded with various antibacterial drugs offers a potential treatment method to enhance the elimination procedure of intracanal biofilms. Clinically, many models of bacterial biofilms have been prepared under in vitro conditions for different aims. The process of drug delivery from polymeric nanofibers is based on the principle that the releasing ratio of drug molecules increases due to the increase in the surface area of the hosted structure. In our review, we discuss diverse approaches of loading/releasing drugs on/from nanofibers and we summarized many studies about electrospun nanofibers loaded various drugs applied in the endodontic field. Moreover, we argued both the advantages and the limitations of these modern endodontic treatment materials comparing them with the traditional ones.

Growth factors, as biological macromolecules in bioactivity enhancing of electrospun wound dressings for diabetic wound healing: A review

Impaired wound healing is of the most conspicuous characteristics of diabetic mellitus. Reduced blood flow, chronic inflammatory reactions, infection, endothelial dysfunction, elevated levels of reactive oxygen species, and metabolic disorders cause wounds to heal more slowly in these patients. Previous studies have reported useful impacts of growth factors in management of such wounds. However, due to their short half-life and low stability, a suitable delivery platform with sustained release profile may boost their healing potential. Controlled and localized delivery of growth factors via electrospun fibers have been extensively explored in previous studies. The electrospinning method; although not new, has turned out to be extremely effective for the preparation of delivery carriers for growth factors. Due to their structural resemblance to native tissues' extracellular matrix, high encapsulation efficacy, tunability, and high surface to volume ratio, electrospun scaffolds have gained significant attention in drug delivery and tissue engineering. In the current review, careful integration of current research regarding the applications of growth factors' delivery through electrospun fibers in diabetic wounds healing has been done. This review will not only give an insight into the current updates, but will also highlights the future perspectives and challenges.

Cyclodextrin-Modified Nanomaterials for Drug Delivery: Classification and Advances in Controlled Release and Bioavailability

In drug delivery, one widely used way of overcoming the biopharmaceutical problems present in several active pharmaceutical ingredients, such as poor aqueous solubility, early instability, and low bioavailability, is the formation of inclusion compounds with cyclodextrins (CD). In recent years, the use of CD derivatives in combination with nanomaterials has shown to be a promising strategy for formulating new, optimized systems. The goals of this review are to give in-depth knowledge and critical appraisal of the main CD-modified or CD-based nanomaterials for drug delivery, such as lipid-based nanocarriers, natural and synthetic polymeric nanocarriers, nanosponges, graphene derivatives, mesoporous silica nanoparticles, plasmonic and magnetic nanoparticles, quantum dots and other miscellaneous systems such as nanovalves, metal-organic frameworks, Janus nanoparticles, and nanofibers. Special attention is given to nanosystems that achieve controlled drug release and increase their bioavailability during in vivo studies.

Antibacterial nanofibers of pullulan/tetracycline-cyclodextrin inclusion complexes for Fast-Disintegrating oral drug delivery

Tetracycline is a widely used antibiotic suffering from poor water solubility and low bioavailability. Here, hydroxypropyl-beta-cyclodextrin (HPβCD) was used to form inclusion complexes (IC) of tetracycline with 2:1 M ratio (CD:drug). Then, tetracycline-HPβCD-IC was mixed with pullulan- a non-toxic, water-soluble biopolymer - to form nanofibrous webs via electrospinning. The electrospinning of pullulan/tetracycline-HPβCD-IC was yielded into defect-free nanofibers collected in the form of a self-standing and flexible material with the loading capacity of ∼ 7.7 % (w/w). Pullulan/tetracycline nanofibers was also generated as control sample having the same drug loading. Tetracycline was found in the amorphous state in case of pullulan/tetracycline-HPβCD nanofibers due to inclusion complexation. Through inclusion complexation with HPβCD, enhanced aqueous solubility and faster release profile were provided for pullulan/tetracycline-HPβCD-IC nanofibers compared to pullulan/tetracycline one. Additionally, pullulan/tetracycline-HPβCD-IC nanofibers readily disintegrated when wetted with artificial saliva while pullulan/tetracycline nanofibers were not completely absorbed by the same simulate environment. Electrospun nanofibers showed promising antibacterial activity against both gram-positive and gram-negative bacteria. Briefly, our findings indicated that pullulan/tetracycline-HPβCD-IC nanofibers could be an attractive material as orally fast disintegrating drug delivery system for the desired antibiotic treatment thanks to its promising physicochemical and antibacterial properties.

Recent advances in polymer scaffolds for biomedical applications

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

Recent developments in polysaccharide-based electrospun nanofibers for environmental applications

Electrospinning has become an inevitable approach to produce nanofibrous structures for diverse environmental applications. Polysaccharides, due to their variety of types, biobased origins, and eco-friendly, and renewable nature are wonderful materials for the said purpose. The present review discusses the electrospinning process, the parameters involved in the formation of electrospun nanofibers in general, and the polysaccharides in specific. The selection of materials to be electrospun depends on the processing conditions and properties deemed desirable for specific applications. Thereby, the conditions to electrospun polysaccharides-based nanofibers have been focused on for possible environmental applications including air filtration, water treatment, antimicrobial treatment, environmental sensing, and so forth. The polysaccharide-based electrospun membranes, for instance, due to their active adsorption sites could find significant potential for contaminants removal from the aqueous systems. The study also gives some recommendations to overcome any shortcomings faced during the electrospinning and environmental applications of polysaccharide-based matrices.

Oleanolic Acid Nanofibers Attenuated Particulate Matter-Induced Oxidative Stress in Keratinocytes

Airborne particulate matter (PM) is one of the indicators of air pollution, and it is also the main factor causing oxidative stress in the skin. Oleanolic acid (OA), a natural terpenoid compound, effectively inhibited PM-induced skin aging; however, OA has poor water solubility and skin absorption, which limit its application in medicines and cosmetics. The aim of this study was to prepare oleanolic acid nanofibers (OAnf) and evaluate the effects of OA and OAnf in PM-treated keratinocytes. The results showed that OA dissolved in dissolved in dimethyl sulfoxide (DMSO) attenuated PM-induced reactive oxygen species overproduction, stress-activated protein kinase/Jun-amino-terminal kinase (SAPK/JNK) activation, and the expressions of inflammatory and skin-aging-related proteins. In addition, the nanofiber process of OA effectively improved the water solubility of OA more than 99,000-fold through changing its physicochemical properties, including a surface area increase, particle size reduction, amorphous transformation, and hydrogen bonding formation with excipients. The skin penetration ability of OAnf was consistently over 10-fold higher than that of OA. Moreover, when dissolved in PBS, OAnf displayed superior antioxidant, anti-inflammatory, and anti-skin aging activities in PM-treated keratinocytes than OA. In conclusion, our findings suggest that OAnf could be a topical antioxidant formulation to attenuate skin problems caused by PM.

Polyvinyl Alcohol/Chitosan Single-Layered and Polyvinyl Alcohol/Chitosan/Eudragit RL100 Multi-layered Electrospun Nanofibers as an Ocular Matrix for the Controlled Release of Ofloxacin: an In Vitro and In Vivo Evaluation

A novel nanofiber insert was prepared with a modified electrospinning method to enhance the ocular residence time of ofloxacin (OFX) and to provide a sustained release pattern by covering hydrophilic polymers, chitosan/polyvinyl alcohol (CS/PVA) nanofibers, with a hydrophobic polymer, Eudragit RL100 in layers, and by glutaraldehyde (GA) cross-linking of CS-PVA nanofibers for the treatment of infectious conjunctivitis. The morphology of the prepared nanofibers was studied using scanning electron microscopy (SEM). The average fiber diameter was found to be 123 ± 23 nm for the single electrospun nanofiber with no cross-linking (OFX-O). The single nanofibers, cross-linked for 10 h with GA (OFX-OG), had an average fiber diameter of 159 ± 30 nm. The amount of OFX released from the nanofibers was measured in vitro and in vivo using UV spectroscopy and microbial assay methods against Staphylococcus aureus, respectively. The antimicrobial efficiency of OFX formulated in cross-linked and non-cross-linked nanofibers was affirmed by observing the inhibition zones of Staphylococcus aureus and Escherichia coli. In vivo studies using the OFX nanofibrous inserts on a rabbit eye confirmed a sustained release pattern for up to 96 h. It was found that the cross-linking of the nanofibers by GA vapor could reduce the burst release of OFX from OFX-loaded CS/PVA in one layer and multi-layered nanofibers. In vivo results showed that the AUC_0–96 for the nanofibers was 9–20-folds higher compared to the OFX solution. This study thus demonstrates the potential of the nanofiber technology is being utilized to sustained drug release in ocular drug delivery systems.

Electrospun Polymer-Free Nanofibers Incorporating Hydroxypropyl-β-cyclodextrin/Difenoconazole via Supramolecular Assembly for Antifungal Activity

In this study, flexible and self-standing hydroxypropyl-β-cyclodextrin/difenoconazole inclusion complex (HPβCD/DZ-IC) nanofibers were prepared by polymer-free electrospinning, which exhibited potential to be a new fast-dissolving pesticide formulation. Scanning electron microscopy and optical microscopy were applied to evaluate the morphology of nanofibers, which showed that the resulting HPβCD/DZ-IC nanofibers were bead-free and uniform. In addition, the proton nuclear magnetic resonance (¹H NMR) spectrum suggested a stoichiometric ratio of 1:0.9 (HPβCD/DZ). Other characterization methods, such as UV-vis absorption, fluorescence spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA), were applied in this study. On the one hand, UV-vis absorption, fluorescence spectroscopy, FT-IR, XRD, and TGA provided useful information for the successful formation of an inclusion complex; on the other hand, the results of TGA indicated the thermal stability of DZ was enhanced after the formation of inclusion complexes. Besides, the phase solubility test could explain the increased water solubility of the nanofibers of inclusion complexes formed by DZ and HPβCD. The results of molecular docking studies demonstrated the most favorable binding interactions when HPβCD combined with DZ. The dissolution test and the antifungal performance test exhibited the characteristics of fast dissolution and the excellent antifungal performance of HPβCD/DZ-IC nanofibers, respectively.

Physicomechanical performance and encapsulation efficiency of β-cyclodextrin loaded functional electrospun mats based on aliphatic polyesters and their blends

Designing complex-forming biodegradable and biocompatible electrospun mats (EMs) by incorporating β- cyclodextrin (β-CD) into polylactic acid (PLA)/poly(ε-caprolactone) (PCL) (70:30 w/w) blend based polyester matrix. The influence of β-CD loading on the morphological, thermal, and microstructural properties was investigated using scanning electron microscopy, differential scanning calorimetry (DSC), thermogravimetric analysis, X-ray diffraction, and Fourier transform infrared spectroscopy. The studies revealed the presence of characteristic interactions between the polymer matrix and β-CD moieties. Further, the quasi-static mechanical properties of EMs were evaluated using a universal testing machine. An enhancement in modulus and strength was obtained for ∼ 2.5-5 phr of β-CD content and beyond ∼ 5 phr of β-CD content, the mechanical properties of EMs were observed to deteriorate. The contact angle studies indicated a decrease in hydrophobicity of PLA/PCL-based EMs with the increase in β-CD content. The swelling and weight loss studies in phosphate buffer saline (PBS) indicated a subsequent release of β-CD from the EMs. FT-IR and ¹H NMR spectra elucidated the removal of curcumin from ethanol-water solutions and its simultaneous encapsulation in β-CD hydrophobic cavities (released) of fabricated EMs. Thus, the study demonstrates the development of aliphatic polyester-based biodegradable-functional EMs with tunable physico-mechanical properties for biomedical applications, facilitating encapsulation and rapid removal of waste hydrophobic ultrafine molecules from the system.

History of cyclodextrin-based polymers in food and pharmacy: a review

Cyclodextrins are glucose macrocycles whose inclusional capabilities towards non-polar solutes can be modulated with the help of other macrostructures. The incorporation of cyclodextrin moieties into larger structures produces five types of new materials: crosslinked networks, functionalized chains, amphiphilic cyclodextrins, polyrotaxanes and nanocomposites. This review presents crosslinking and grafting to prepare covalently-attached cyclodextrins, and applications in the food and pharmaceutical sectors, from an historical point of view. In food science, applications include debittering of juices, retention of aromas and release of preservatives from packaging. In biomedical science, cyclodextrin polymers are applied classically to drug release, and more recently to gene delivery and regenerative medicine. The remarkable points are: 1) epichlorohydrin and diisocyanates have been extensively used as crosslinkers since the 1960s, but during the last two decades more complex cyclodextrin polymeric structures have been designed. 2) The evolution of cyclodextrin polymers matches that of macromolecular materials with regard to complexity, functionality and capabilities. 3) The use of cyclodextrin polymers as sorbents in the food sector came first, but smart packaging is now an active challenge. Cyclodextrins have also been recently used to design treatments against the coronavirus disease 2019 (COVID-19).

Polymer-free cyclodextrin and natural polymer-cyclodextrin electrospun nanofibers: A comprehensive review on current applications and future perspectives

The present review discusses the use of cyclodextrins and their derivatives to prepare electrospun nanofibers with specific features. Cyclodextrins, owing to their unique capability to form inclusion complexes with hydrophobic and volatile molecules, can indeed facilitate the encapsulation of bioactive compounds in electrospun nanofibers allowing fast-dissolving products for food, biomedical, and pharmaceutical purposes, filtering materials for wastewater and air purification, as well as a variety of other technological applications. Additionally, cyclodextrins can improve the processability of naturally occurring biopolymers helping the fabrication of "green" materials with a strong industrial relevance. Hence, this review provides a comprehensive state-of-the-art of different cyclodextrins-based nanofibers including those made of pure cyclodextrins, of polycyclodextrins, and those made of natural biopolymer functionalized with cyclodextrins. To this end, the advantages and disadvantages of such approaches and their possible applications are investigated along with the current limitations in the exploitation of electrospinning at the industrial level.