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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. [ABSTRACT FROM AUTHOR]

Hollow polymer microfibers with variable microstructural and hydrophilic properties were proposed as building elements to create axon‐mimicking phantoms for validation of diffusion tensor imaging (DTI). The axon‐mimicking microfibers were fabricated in a mm‐thick 3D anisotropic fiber strip, by direct jet coaxial electrospinning of PCL/polysiloxane‐based surfactant (PSi) mixture as shell and polyethylene oxide (PEO) as core. Hydrophilic PCL‐PSi fiber strips were first obtained by carefully selecting appropriate solvents for the core and appropriate fiber collector rotating and transverse speeds. The porous cross‐section and anisotropic orientation of axon‐mimicking fibers were then quantitatively evaluated using two ImageJ plugins—nearest distance (ND) and directionality based on their scanning electron microscopy (SEM) images. Third, axon‐mimicking phantom was constructed from PCL‐PSi fiber strips with variable porous‐section and fiber orientation and tested on a 3T clinical MR scanner. The relationship between DTI measurements (mean diffusivity [MD] and fractional anisotropy [FA]) of phantom samples and their pore size and fiber orientation was investigated. Two key microstructural parameters of axon‐mimicking phantoms including normalized pore distance and dispersion of fiber orientation could well interpret the variations in DTI measurements. Two PCL‐PSi phantom samples made from different regions of the same fiber strips were found to have similar MD and FA values, indicating that the direct jet coaxial electrospun fiber strips had consistent microstructure. More importantly, the MD and FA values of the developed axon‐mimicking phantoms were mostly in the biologically relevant range. [ABSTRACT FROM AUTHOR]

[Display omitted] In this work ethyl cellulose (EC) was used as a matrix polymer and loaded with captopril, with the goal to fabricate electrospun fibers as potential sustained-release floating gastro-retentive drug delivery systems. Fibers were prepared with monoaxial and coaxial electrospinning, and both bench-top and scaled-up (needle-based) methods were explored. With monoaxial electrospinning, EC-based fibers in the shape of cylinders and with smooth surfaces were obtained both at 1 and 20 mL/h. For coaxial electrospinning, the drug was encapsulated in the core and fibers generated with core/shell feeding rates of 0.5/1 and 5/10 mL/h. These fibers were cylindrical in shape with a wrinkled surface, and confocal microscopy suggested them to have a core/shell structure. X-ray diffraction and differential scanning calorimetry results showed that all the fibers were amorphous. The encapsulation efficiency of all the formulations was almost 100%. Release studies in simulated gastric fluid indicated that the monoaxial electrospun fibers gave slower release profiles compared with a physical mixture of captopril and EC, but there was still an initial "burst" of release at the start of the experiment. Fibers with low drug-loading (9.09% w/w) showed a slower release than fibers with high loading (23.08% w/w). The coaxial fibers exhibited sustained release profiles with reduced initial burst release. Both monoaxial and coaxial fibers could float on the surface of simulated gastric fluid for over 24 h at 37 °C. After storage under ambient conditions (19–21 °C, relative humidity 30–40%) for 8 weeks, all the fibers remained amorphous and the release profiles had no significant changes compared with fresh fibers. This work thus highlights the potential of coaxial electrospinning for fabricating a sustained-release floating gastro-retentive drug delivery system for captopril. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Increasing numbers of elderly people require multi-drug therapies. One route to improve adherence rates is to prepare fixed dose combinations (FDCs), in which multiple active ingredients are loaded into a single formulation. Here, we report the use of electrospinning to prepare fast-dissolving oral FDCs containing amlodipine besylate and valsartan, two drugs prescribed as FDCs for the treatment of hypertension. Electrospun fibers were prepared loaded with one or both drugs, using polyvinylpyrrolidone as the polymer matrix. The fibers were largely cylindrical in morphology and comprise amorphous solid dispersions except with the highest loadings of amlodipine besylate. HPLC demonstrated drug entrapment efficiencies of >85% of the theoretical dose. The mats have folding endurances and thicknesses suitable for use as oral films. The amlodipine besylate-loaded systems are fast-dissolving, with >90% release obtained within 120 s. In contrast, valsartan release from its single-drug formulations took longer, ranging from 360 s to 24 min. With the FDC formulations, rapid release within 360 s was achieved when the loading was 5% w/w of each drug, but again the release time increased with drug loading. Electrospun fibers therefore have significant promise as FDCs, but the target drug and its loading need to be carefully considered. [ABSTRACT FROM AUTHOR]

In this work, we report electrospun nanofibers made of model hydrophobic (poly(lactide- co -ε-caprolactone); PLCL) and hydrophilic (gelatin) polymers. We explored the effect on drug release of the incorporation of sodium bicarbonate (SB) into these fibers, using the potent antibacterial agent ciprofloxacin as a model drug. The fibers prepared are smooth and have relatively uniform diameters lying between ca. 600 and 850 nm. The presence of ciprofloxacin in the fibers was confirmed using IR spectroscopy. X-ray diffraction showed the drug to be incorporated into the fibers in the amorphous form. In vitro drug release studies revealed that, as expected, more rapid drug release was seen with gelatin fibers than those made of PLCL, and a greater final release percentage was obtained. The inclusion of SB in the gelatin fibers imparts them with pH sensitivity: gelatin/SB fibers showed faster release at pH 5 than pH 7.4, while fibers without SB gave the same release profiles at both pHs. The PLCL fibers have no pH sensitivity, even when SB was included, as a result of their hydrophobic structure precluding the ingress of solvent. In vitro cell culture studies showed that all the fibers are able to promote cell proliferation. The ciprofloxacin loaded fibers are effective in inhibiting Escherichia coli and Staphylococcus aureus growth in antibacterial tests. Thus, the gelatin-based fibers can be used as pH-responsive drug delivery systems, with potential applications for instance in the treatment of tumor resection sites. Should these become infected, the pH would drop, resulting in ciprofloxacin being released and the infection halted. [ABSTRACT FROM AUTHOR]

Medicines based on vascular endothelial growth factor (VEGF) neutralising antibodies such as bevacizumab have revolutionized the treatment of age related macular degeneration (AMD), a common blinding disease, and have great potential in preventing scarring after surgery or accelerating the healing of corneal injuries. However, at present frequent invasive injections are required to deliver these antibodies. Such administration is uncomfortable for patients and expensive for health service providers. Much effort is thus focused on developing dosage forms that can be administered less frequently. Here we use electrospinning to prepare a solid form of bevacizumab designed for prolonged release while maintaining antibody stability. Electrospun fibers were prepared with bevacizumab encapsulated in the core, surrounded by a poly-ε-caprolactone sheath. The fibers were generated using aqueous bevacizumab solutions buffered at two different pH values: 6.2 (the pH of the commercial product; F beva ) and 8.3 (the isoelectric point of bevacizumab; F bevaP ). The fibers had smooth and cylindrical morphologies, with diameters of ca. 500 nm. Both sets of bevacizumab loaded fibers gave sustained release profiles in an in vitro model of the subconjunctival space of the eye. F beva displayed first order kinetics with t 1/2 of 11.4 ± 4.4 days, while F bevaP comprises a zero-order reservoir type release system with t 1/2 of 52.9 ± 14.8 days. Both SDS-PAGE and surface plasmon resonance demonstrate that the bevacizumab in F bevaP did not undergo degradation during fiber fabrication or release. In contrast, the antibody released from F beva had degraded, and failed to bind to VEGF. Our results demonstrate that pH control is crucial to maintain antibody stability during the fabrication of core/shell fibers and ensure release of functional protein. Statement of Significance Bevacizumab is a potent protein drug which is highly effective in the treatment of degenerative conditions in the eye. To be effective, frequent injections into the eye are required, which is deeply unpleasant for patients and expensive for healthcare providers. Alternative methods of administration are thus highly sought after. In our work, we use the electrospinning technique to prepare fiber-based formulations loaded with bevacizumab. By careful control of the experimental parameters we are able to stabilize the protein during processing and ensure a constant rate of release over more than two months in vitro . These fibers could thus be used to reduce the frequency of dosing required, reducing cost and improving patient outcomes. [ABSTRACT FROM AUTHOR]

In this work, we aimed to develop new materials to reduce the secondary injuries which can be imparted when replacing wound dressings. Electrospun fibers based on the thermoresponsive polymer poly( N -isopropylacrylamide) (PNIPAAm), poly( l -lactic acid- co -ɛ-caprolactone) (PLCL), and the antibiotic ciprofloxacin (CIF) were prepared. The water contact angle of fibers made from a blend of PNIPAAm and PLCL changed dramatically when the temperature was increased above 32 °C. Sustained release of CIF from the formulations was observed over > 200 h. Moreover, L929 fibroblasts could proliferate on the fibers, indicating their biocompatibility. The CIF-loaded fibers were found to have potent antibacterial activity against E . coli and S . aureus . In vivo tests on rats indicated that CIF-loaded thermosensitive fibers have enhanced healing performance compared to CIF-loaded PLCL fibers or a commercial gauze. Electrospun PNIPAAm/PLCL fibers loaded with CIF thus have great promise in the development of new wound dressing materials. [ABSTRACT FROM AUTHOR]

The tissue integration of synthetic polymers can be promoted by displaying RGD peptides at the biointerface with the objective of enhancing colonization of the material by endogenous cells. A firm but flexible attachment of the peptide to the polymer matrix, still allowing interaction with receptors, is therefore of interest. Here, the covalent coupling of flexible physical anchor groups, allowing for temporary immobilization on polymeric surfaces via hydrophobic or dipole-dipole interactions, to a RGD peptide was investigated. For this purpose, a stearate or an oligo(ethylene glycol) (OEG) was attached to GRGDS in 51-69% yield. The obtained RGD linker constructs were characterized by NMR, IR and MALDI-ToF mass spectrometry, revealing that the commercially available OEG and stearate linkers are in fact mixtures of similar compounds. The RGD linker constructs were co-electrospun with poly( p-dioxanone) (PPDO). After electrospinning, nitrogen could be detected on the surface of the PPDO fibers by X-ray photoelectron spectroscopy. The nitrogen content exceeded the calculated value for the homogeneous material mixture suggesting a pronounced presentation of the peptide on the fiber surface. Increasing amounts of RGD linker constructs in the electrospinning solution did not lead to a detection of an increased amount of peptide on the scaffold surface, suggesting inhomogeneous distribution of the peptide on the PPDO fiber surface. Human adipose-derived stem cells cultured on the patches showed similar viability as when cultured on PPDO containing pristine RGD. The fully characterized RGD linker constructs could serve as valuable tools for the further development of tissue-integrating polymeric scaffolds. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Nanoscale drug depots, comprising a drug reservoir surrounded by a carrier membrane, are much sought after in contemporary pharmaceutical research. Using cellulose acetate (CA) as a filament-forming polymeric matrix and ferulic acid (FA) as a model drug, nanoscale drug depots in the form of core-shell fibers were designed and fabricated using a modified tri-axial electrospinning process. This employed a solvent mixture as the outer working fluid, as a result of which a robust and continuous preparation process could be achieved. The fiber-based depots had a linear morphology, smooth surfaces, and an average diameter of 0.62 ± 0.07 μm. Electron microscopy data showed them to have clear core-shell structures, with the FA encapsulated inside a CA shell. X-ray diffraction and IR spectroscopy results verified that FA was present in the crystalline physical form. In vitro dissolution tests revealed that the fibers were able to provide close to zero-order release over 36 h, with no initial burst release and minimal tailing-off. The release properties of the depot systems were much improved over monolithic CA/FA fibers, which exhibited a significant burst release and also considerable tailing-off at the end of the release experiment. Here we thus demonstrate the concept of using modified tri-axial electrospinning to design and develop new types of heterogeneous nanoscale biomaterials. Statement of Significance Nanoscale drug depots with a drug reservoir surrounded by a carrier are highly attractive in biomedicine. A cellulose acetate based drug depot was investigated in detail, starting with the design of the nanostructure, and moving through its fabrication using a modified tri-axial electrospinning process and a series of characterizations. The core-shell fiber-based drug depots can provide a more sustained release profile with no initial burst effect and less tailing-off than equivalent monolithic drug-loaded fibers. The drug release mechanisms are also distinct in the two systems. This proof-of-concept work can be further expanded to conceive a series of new structural biomaterials with improved or new functional performance. [ABSTRACT FROM AUTHOR]

To obtain wound dressings which could be removed easily without secondary injuries, we prepared thermoresponsive electrospun fiber mats containing poly(di(ethylene glycol) methyl ether methacrylate) (PDEGMA). Blend fibers of PDEGMA and poly( l -lactic acid-co-ε-caprolactone) (P(LLA-CL) were fabricated via electrospinning, and analogous fibers containing the antibiotic ciprofloxacin (CIF) were also prepared. Smooth cylindrical fibers were obtained, albeit with a small amount of beading visible for the ciprofloxacin-loaded fibers. X-ray diffraction showed the drug to exist in the amorphous physical form post-electrospinning. The composite fibers showed distinct thermosensitive properties and gave sustained release of CIF over more than 160 h in vitro . The fibers could promote the proliferation of fibroblasts, and by varying the temperature cells could easily be attached to and detached from the fibers. Antibacterial tests demonstrated that fibers loaded with ciprofloxacin were effective in inhibiting the growth of E. coli and S. aureus . In vivo investigations on rats indicated that the composite PDEGMA/P(LLA-CL) fibers loaded with CIF had much more potent wound healing properties than a commercial gauze and CIF-loaded fibers made solely of P(LLA-CL). These results demonstrate the potential of PDEGMA/P(LLA-CL)/ciprofloxacin fibers as advanced wound dressing materials. [ABSTRACT FROM AUTHOR]

A modified tri-axial electrospinning process was developed for the generation of a new type of pH-sensitive polymer/lipid nanocomposite. The systems produced are able to promote both dissolution and permeation of a model poorly water-soluble drug. First, we show that it is possible to run a tri-axial process with only one of the three fluids being electrospinnable. Using an electrospinnable middle fluid of Eudragit S100 (ES100) with pure ethanol as the outer solvent and an unspinnable lecithin-diclofenac sodium (PL–DS) core solution, nanofibers with linear morphology and clear core/shell structures can be fabricated continuously and smoothly. X-ray diffraction proved that these nanofibers are structural nanocomposites with the drug present in an amorphous state. In vitro dissolution tests demonstrated that the formulations could preclude release in acidic conditions, and that the drug was released from the fibers in two successive steps at neutral pH. The first step is the dissolution of the shell ES100 and the conversion of the core PL–DS into sub-micron sized particles. This frees some DS into solution, and later the remaining DS is gradually released from the PL–DS particles through diffusion. Ex vivo permeation results showed that the composite nanofibers give a more than twofold uplift in the amount of DS passing through the colonic membrane as compared to pure DS; 74% of the transmitted drug was in the form of PL–DS particles. The new tri-axial electrospinning process developed in this work provides a platform to fabricate structural nanomaterials, and the core–shell polymer-PL nanocomposites we have produced have significant potential applications for oral colon-targeted drug delivery. Statement of Significance A modified tri-axial electrospinning is demonstrated to create a new type of core–shell pH-sensitive polymer/lipid nanocomposites, in which an electrospinnable middle fluid is exploited to support the un-spinnable outer and inner fluids. The structural nanocomposites are able to provide a colon-targeted sustained release and an enhanced permeation performance of diclofenac sodium. The developed tri-axial process can provide a platform for fabricating new structural nanomaterials with high quality. The strategy of a combined usage of polymeric excipients and phospholipid in a core–shell format should provide new possibilities of developing novel drug delivery systems for efficacious oral administration of poorly-water soluble drugs. [ABSTRACT FROM AUTHOR]

ABSTRACT A facile and efficient protocol for the preparation of nanofibers incorporating polymeric ketoprofen prodrugs and polyvinylpyrrolidone was developed. Polymeric ketoprofen prodrugs were constructed by a two-step chemo-enzymatic synthetic route, and nanofibers prepared by electrospinning from dimethylformamide/ethanol (1 : 1, v/v) solutions. The morphological characteristics of the fibers were influenced by the concentration of active agent in the spinning solution; average diameters varied from 196 to 370 nm. In vitro release studies indicated that the ketoprofen release rate from the electrospun fibers was significantly higher than that from the pure polymeric prodrugs. Cumulative drug release from the electrospun fibers reached 40-70% after 3 h and 75-100% after 12 h, while the pure polymeric prodrug released only 7-9% of the active agent over 12 h. Functional nanofibers incorporating polymeric prodrugs therefore comprise potentially effective drug delivery systems for sustained release. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1570-1577, 2013 [ABSTRACT FROM AUTHOR]

Abstract: Polyvinyl alcohol (PVA) nanofibers loaded with curcumin or its β-cyclodextrin (CD) inclusion complex were successfully prepared using an electrospinning process. The influence of curcumin or CD–curcumin complex content on fiber formation and quality was investigated. X-ray diffraction and differential scanning calorimetry analyses of the fibers, together with electron microscope evidence, demonstrated that curcumin is likely to be present as crystalline aggregates in the fibers, while its CD complex is more evenly distributed. 1H NMR analysis indicated that the chemical structure of curcumin was preserved during the electrospinning process. Thermogravimetric analysis demonstrated that inclusion into nanofibers enhanced the thermal stability of curcumin. In vitro dissolution tests showed that the drug release profiles of the PVA/curcumin and PVA/complex fibers were different, with release from the latter occurring more rapidly. Release from both fiber types was found to be largely governed by a diffusion-controlled mechanism; two sequential stages for drug release were observed. [Copyright &y& Elsevier]

Abstract: With sodium dodecylbenzene sulfonate (SDBS) solutions in N,N-Dimethylformamide (DMF) as sheath fluids to surround the core polymer solutions, a series of polyacrylonitrile (PAN) nanofibers with fine diameters, narrow diameter distributions, smooth surfaces and uniform structures have been successfully generated. The fiber diameters (D, nm) could be manipulated through adjusting the SDBS concentration in the sheath fluid (C, mgml−1) with a scaling law of D =790 C −0.41 (R 2 =0.9903) within a range of 5–50mgml−1. The mechanism of sheath SDBS solutions on the evaporation of DMF and the solidification of core polymer jets is discussed. The replacement of SDBS solutions for traditional atmosphere in single fluid electrospinning can lend itself to smoothen the electrospinning process through adjusting the core solvent evaporation rate. It is concluded that coaxial electrospinning with an ion surfactant solution comprises a facile process for producing high quality polymer nanofibers. [Copyright &y& Elsevier]

Electrospinning is an inexpensive and powerful method that employs a polymer solution and strong electric field to produce nanofibers. These can be applied in diverse biological and medical applications. Due to their large surface area, controllable surface functionalization and properties, and typically high biocompatibility electrospun nanofibers are recognized as promising materials for the manufacturing of drug delivery systems. Electrospinning offers the potential to formulate poorly soluble drugs as amorphous solid dispersions to improve solubility, bioavailability and targeting of drug release. It is also a successful strategy for the encapsulation of nutraceuticals. This review aims to briefly discuss the concept of electrospinning and recent progress in manufacturing electrospun drug delivery systems. It will further consider in detail the encapsulation of nutraceuticals, particularly probiotics. [ABSTRACT FROM AUTHOR]

The socioeconomic impact of osteochondral (OC) damage has been increasing steadily over time in the global population, and the promise of tissue engineering in generating biomimetic tissues replicating the physiological OC environment and architecture has been falling short of its projected potential. The most recent advances in OC tissue engineering are summarised in this work, with a focus on electrospun and 3D printed biomaterials combined with stem cells and biochemical stimuli, to identify what is causing this pitfall between the bench and the patients' bedside. Even though significant progress has been achieved in electrospinning, 3D-(bio)printing, and induced pluripotent stem cell (iPSC) technologies, it is still challenging to artificially emulate the OC interface and achieve complete regeneration of bone and cartilage tissues. Their intricate architecture and the need for tight spatiotemporal control of cellular and biochemical cues hinder the attainment of long-term functional integration of tissue-engineered constructs. Moreover, this complexity and the high variability in experimental conditions used in different studies undermine the scalability and reproducibility of prospective regenerative medicine solutions. It is clear that further development of standardised, integrative, and economically viable methods regarding scaffold production, cell selection, and additional biochemical and biomechanical stimulation is likely to be the key to accelerate the clinical translation and fill the gap in OC treatment. [ABSTRACT FROM AUTHOR]

Recently, the electrospinning (ES) process has been extensively studied due to its potential applications in various fields, particularly pharmaceutical and biomedical purposes. The production rate using typical ES technology is usually around 0.01–1 g/h, which is lower than pharmaceutical industry production requirements. Therefore, different companies have worked to develop electrospinning equipment, technological solutions, and electrospun materials into large-scale production. Different approaches have been explored to scale-up the production mainly by increasing the nanofiber jet through multiple needles, free-surface technologies, and hybrid methods that use an additional energy source. Among them, needleless and centrifugal methods have gained the most attention and applications. Besides, the production rate reached (450 g/h in some cases) makes these methods feasible in the pharmaceutical industry. The present study overviews and compares the most recent ES approaches successfully developed for nanofibers' large-scale production and accompanying challenges with some examples of applied approaches in drug delivery systems. Besides, various types of commercial products and devices released to the markets have been mentioned. [ABSTRACT FROM AUTHOR]

A human panel study was performed to investigate the acceptability of orodispersible electrospun and solvent cast films. 50 healthy volunteers took two drug-free samples of polyvinyl alcohol films prepared by the two methods. On a 5-point hedonic scale, the volunteers assessed the films' perceived size, stickiness, thickness, disintegration time, thickening effect on saliva, and handling. The films manufactured by both methods were similar in their end-user acceptability. The modal values of perceived size, thickness, disintegration time, saliva thickening effect, and handling were high (4 or 5). However, for both, the stickiness mode was 2 (strongly sticky) and the only negative attribute. Both films were reported to take approximately 30 s to disintegrate completely in the mouth. Electrospun films scored similarly high to solvent cast orodispersible films in most attributes of end-user acceptability. Electrospun films were marginally preferred, with 27 out of 50 participants picking electrospinning when presented with a forced choice test of both fabrication methods. This is the first study to show that electrospinning enables the fabrication of orodispersible films that are acceptable to adult human participants in terms of handling and mouthfeel and suggests that the potential for clinical translation of such formulations is high. [ABSTRACT FROM AUTHOR]

Electrospinning has emerged as a powerful strategy to develop controlled release drug delivery systems but the effects of post-fabrication solvent vapor annealing on drug-loaded electrospun fibers have not been explored to date. In this work, electrospun poly(ε-caprolactone) (PCL) fibers loaded with the hydrophobic small-molecule spironolactone (SPL) were explored. Immediately after fabrication, the fibers are smooth and cylindrical. However, during storage the PCL crystallinity in the fibers is observed to increase, demonstrating a lack of stability. When freshly-prepared fibers are annealed with acetone vapor, the amorphous PCL chains recrystallize, resulting in the fiber surfaces becoming wrinkled and yielding shish-kebab like structures. This effect does not arise after the fibers have been aged. SPL is found to be amorphously dispersed in the PCL matrix both immediately after electrospinning and after annealing. In vitro dissolution studies revealed that while the fresh fibers show a rapid burst of SPL release, after annealing more extended release profiles are observed. Both the rate and extent of release can be varied through changing the annealing time. Further, the annealed formulations are shown to be stable upon storage. [ABSTRACT FROM AUTHOR]

The formation of nanoscale fibers from pH-sensitive polymers is a route which has been widely explored for targeted drug delivery. In particular, the Eudragit L100 and S100 families of polymers have received significant attention for this purpose. However, while in some cases it is shown that making drug-loaded Eudragit polymers effectively prevents drug release in low-pH media where the polymer is insoluble, this is not always the case, and other studies have reported significant amounts of drug release at acidic pHs. In this study, we sought to gain insight into the factors influencing the release of active ingredients from Eudragit S100 (ES100) fibers. A family of materials was prepared loaded with the model active ingredients (AIs) benzoic acid, 1-naphthoic acid, 1-naphthylamine, and 9-anthracene carboxylic acid. Analogous systems were prepared with an AI-loaded core and an ES100 sheath. The resultant fibers were smooth and cylindrical in the majority of cases, and X-ray diffraction and differential scanning calorimetry showed them to comprise amorphous solid dispersions. When AI release from the monolithic fibers was probed, it was found that there was significant release at pH 1 in all cases except with 9-anthracene carboxylic acid. Analysis of the results indicated that both the molecular weight of the AI and its acidity/basicity are important in controlling release, with lower molecular weight AIs and basic species released more quickly. The same release trends are seen with the core/shell fibers, but AI release at pH 1 is attenuated. The most significant change between the monolithic and core/shell systems was observed in the case of 1-naphthylamine. Mathematical equations were devised to connect molecular properties and AI release under acidic conditions. [ABSTRACT FROM AUTHOR]

Abstract The development of oral dosage forms for poorly water-soluble active pharmaceutical ingredients (APIs) is a persistent challenge. A range of methods has been explored to address this issue, and amorphous solid dispersions (ASDs) have received increasing attention. ASDs are typically prepared by starting with a liquid precursor (a solution or melt) and applying energy for solidification. Many techniques can be used, with the emergence of electrospinning as a potent option in recent years. This method uses electrical energy to induce changes from liquid to solid. Through the direct applications of electrical energy, electrospinning can generate nanofiber-based ASDs from drug-loaded solutions, melts and melt-solutions. The technique can also be combined with other approaches using the application of mechanical, thermal or other energy sources. Electrospinning has numerous advantages over other approaches to produce ASDs. These advantages include extremely rapid drying speeds, ease of implentation, compatibility with a wide range of active ingredients (including those which are thermally labile), and the generation of products with large surface areas and high porosity. Furthermore, this technique exhibits the potential to create so-called 'fifth-generation' ASDs with nanostructured architectures, such as core/shell or Janus systems and their combinations. These advanced systems can improve dissolution behaviour and provide programmable drug release profiles. Additionally, the fiber components and their spatial distributions can be precisely controlled. Electrospun fiber-based ASDs can maintain an incorporated active ingredient in the amorphous physical form for prolonged periods of time because of their homogeneous drug distribution within the polymer matrix (typically they comprise solid solutions), and ability to inhibit molecular motion. These ASDs can be utilised to generate oral dosage forms for poorly water-soluble drugs, resulting in linear or multiple-phase release of one or more APIs. Electrospun ASDs can also be exploited as templates for manipulating molecular self-assembly, offering a bridge between ASDs and other types of dosage forms. This review addresses the development, advantages and pharmaceutical applications of electrospinning for producing polymeric ASDs. Material preparation and analysis procedures are considered. The mechanisms through which performance has been improved are also discussed. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Thermosensitive PNVCL was synthesized by radical polymerization. • PNVCL/EC/Eudragit hybrid fibers were fabricated by twin-jet electrospinning. • The wettability of PNVCL-containing fibers changed as the temperature increased. • KET loaded-fibers showed dual-sensitive properties with sustained release. Abstract We report a dual-responsive drug delivery system prepared by electrospinning. Blend fibers of poly(N-vinylcaprolactam) (PNVCL) and ethyl cellulose (EC) were first prepared, with the aim of developing thermoresponsive sustained release formulations. Eudragit L100-based fibers were then generated to yield pH-sensitive materials. Attempts to produce three-polymer fibers of EC, PNVCL and Eudragit were unsuccessful, and therefore hybrid mats containing two fiber populations (one made of PNVCL/EC, one comprising Eudragit) were instead fabricated by twin-jet electrospinning. Analogous drug-loaded versions of all the formulations were also prepared containing ketoprofen (KET). The fibers were largely smooth and homogeneous, and the addition of KET did not affect their morphology. The PNVCL-containing fiber mats changed from being hydrophilic to hydrophobic when the temperature was increased through the lower critical solution temperature of 33 °C. In vitro drug release profiles showed that the hybrid fiber mats were able to combine the properties of the three polymers, exhibiting both pH-sensitive and thermosensitive properties with sustained release. In addition, they were found to be nontoxic and suitable for cell growth. This study therefore demonstrates that PNVCL/EC/KET-Eudragit/KET multicomponent fiber mats comprise effective and biocompatible materials for targeted drug delivery. [ABSTRACT FROM AUTHOR]

Electrospinning was used to prepare core/shell fibers containing the active pharmaceutical ingredients indomethacin (IMC) or mebeverine hydrochloride (MB-HCl). The shell of the fibers was fabricated from the pH sensitive Eudragit S100 polymer, while the drug-loaded core was based on the mucoadhesive poly(ethylene oxide) (PEO). Three different drug loadings (from 9 to 23% (w/w) of the core mass) were prepared, and for MB-HCl two different molecular weights of PEO were explored. The resultant fibers generally comprise smooth cylinders, although in some cases defects such as surface particles or flattened or merged fibers were visible. Transmission electron microscopy showed all the systems to have clear core and shell compartments. The drugs are present in the amorphous physical form in the fibers. Dissolution tests found that the fibers can effectively prevent release in acidic conditions representative of the stomach, particularly for the acidic indomethacin. After transfer to a pH 7.4 medium, sustained release over between 6 and 22 h is observed. Given the mucoadhesive nature of the PEO core, after dissolution of the shell the fibers will be able to adhere to the walls of the intestinal tract and give sustained local drug release. This renders them promising for the treatment of conditions such as irritable bowel disease and colon cancer. [ABSTRACT FROM AUTHOR]

Fibers of poly(N-isopropylacrylamide) (PNIPAAm), ethyl cellulose (EC), and a blend of both were successfully fabricated by electrospinning. Analogous drug-loaded fibers were prepared loaded with ketoprofen (KET). Scanning and transmission electron microscopy showed that the fibers were largely smooth and cylindrical, with no phase separation observed. The addition of KET to the spinning solutions did not affect the morphology of resultant fibers, and no drug particles could be observed to separate from the polymer matrix. X-ray diffraction demonstrated that the drug was present in the amorphous physical form in the fiber matrix. There are significant intermolecular interactions between KET and polymers, as evidenced by IR spectroscopy and molecular modeling. Water contact angle measurements proved that the PNIPAAm and PNIPAAm/EC fibers switched from being hydrophilic to hydrophobic when the temperature was increased through the lower critical solution temperature of 32°C. In vitro drug release studies found that the PNIPAAm/EC blend nanofibers were able to synergistically combine the properties of the 2 polymers, giving temperature-sensitive systems with sustained release properties. In addition, they were established to be nontoxic and suitable for cell growth. This study demonstrates that electrospun-blend PNIPAAm/EC fibers comprise effective and biocompatible materials for drug delivery systems and tissue engineering. [ABSTRACT FROM AUTHOR]

Highlights: [•] A facile way to produce magnetic liposomes by self-assembly from electrospun nanofibers is proposed. [•] The size of the magnetic liposomes can be controlled by varying the Fe3O4 content in the precursor fibers. [•] The self-assembled liposomes are found to be stable and well dispersed, and to retain the magnetic properties of the Fe3O4 nanoparticles. [•] An outline mechanism for the self-assembly process is proposed. [Copyright &y& Elsevier]

Both fast dissolving and sustained release drug delivery systems (DDSs) comprising mebeverine hydrochloride ( MB- HCl) embedded in either povidone ( PVP) K60 or Eudragit® L 100-55 nanofibers have been prepared by electrospinning. The fibers are found to have cylindrical morphologies with smooth surfaces, except at high drug loadings that appear to induce surface roughness ( PVP) or fragmentation ( Eudragit). There is a general increase in fiber diameter with drug loading. Differential scanning calorimetry and X-ray diffraction demonstrate that the drug exists in an amorphous state in the fibers. Infrared spectroscopy data indicate that the drug has good compatibility with the polymer, whereas nuclear magnetic resonance spectroscopy and high-performance liquid chromatography analyses confirmed that the MB- HCl was not degraded during the spinning process. In vitro dissolution tests of the PVP fiber mats show them to dissolve within 10 s, an improved dissolution profile over the pure drug. The Eudragit fibers show p H-dependent drug release profiles, with only very limited release at p H 2.0 but sustained release over approximately 8 h at p H 6.8. The Eudragit nanofibers have the potential to be developed as oral DDSs for localized drug release in the intestinal tract, whereas the PVP materials may find the application as buccal delivery systems or suppositories. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:283-292, 2014 [ABSTRACT FROM AUTHOR]

Poor aqueous solubility and low stability are major problems which prevent curcumin exerting potent physiological activity. To overcome these challenges, this study fabricated zein-succinic acid modified cyclodextrin (SACD) nanofibers using the electrospinning technology. By optimising the proportion of SACD in the nanofibers, homogenous cylindrical fibers with a uniform size distribution could be obtained. The maximum loading capacity of the optimized nanofibers for curcumin was ca. 35.7 mg/g, as demonstrated by X-ray diffraction and differential scanning calorimetry. No cytotoxicity was observed for any of the Zein/SACD and curcumin-loaded Zein/SACD (Cur-Zein/SACD) nanofibers. The stability of curcumin in the Cur-Zein/SACD nanofibers was significantly improved (compared to the raw material) under conditions mimicking gastrointestinal environments and common heat sterilization processes. In a digestion study, less than 18% of the curcumin loading was released in simulated upper digestive tract conditions, suggesting most of the drug cargo should be able to reach the lower digestive tract and be utilized by the gut microbiota. This study suggests that Zein/SACD nanofibers could be a highly effective strategy for the encapsulation, stabilization and delivery of bioactive compounds, showing potential for food, pharmaceutical, and cosmetic products. [Display omitted] • Zein/SACD nanofibers with uniform cylindrical morphology were prepared. • The loading capacity of curcumin in Zein/SACD nanofibers reached up to 35.7 mg/g. • The stability of curcumin was much enhanced after loading in Zein/SACD nanofibers. • Up to 82% of curcumin in the fibers was able to reach the lower digestive tract. [ABSTRACT FROM AUTHOR]

Abstract: In this study, drug-loaded nanofibers were prepared by electrospinning captopril (CPL) with aliphatic biodegradable polyesters. Poly(l-lactic acid) (PLLA), poly(lactic-co-glycolic acid) (PLGA), and poly(lactic-co-ɛ-caprolactone) (PLCL) were used as filament-forming matrix polymers, and the concentration of CPL in each fiber type was varied. Scanning electron microscopy indicated that the morphology and diameters of the fibers were influenced by the concentration of polymer in the spinning solution and the drug loading. CPL was found to be distributed in the polymer fibers in an amorphous manner using differential scanning calorimetry and X-ray diffraction. FTIR indicated that hydrogen bonding existed between the drug molecules and the carrier polymers. In vitro dissolution tests showed that drug release from the fibers was highly dependent on the release medium, temperature, and on the polymer used. A range of kinetic models were fitted to the drug-release data obtained, and indicated that release was diffusion controlled in all cases. The different polymer fibers have application in diverse areas of drug delivery, for instance as sub-lingual or sustained release systems. Furthermore, by combining different CPL-loaded fibers, it would be possible to produce a bespoke formulation with tailored drug-release properties. [Copyright &y& Elsevier]

[Display omitted] Fixed dose combinations (FDCs) offer an accessible way to simplify complex therapeutic regimens by the simultaneous presentation of multiple drugs in a single entity to the patient. However, encapsulation of hydrophobic drugs into FDCs possess a number of technical challenges. Electrospinning comprises a convenient way to incorporate multiple hydrophobic drugs into a single formulation in a single step, via the use of an appropriate organic solvent system during fabrication. In this study, we report a series of novel fiber formulations comprising ethyl cellulose loaded with two hydrophobic drugs, spironolactone and nifedipine, either individually or in combination. The drugs are found to be present in the fibers in the form of amorphous solid dispersions, and these are stable at room temperature for 4 months. The products showed extended release profiles over more than 30 h. This formulation strategy offers potential to manage chronic cardiovascular conditions and overcome patient related non-adherence by providing a simplified treatment model. [ABSTRACT FROM AUTHOR]

[Display omitted] Surface functionalisation of polymeric electrospun scaffolds with therapeutic biomolecules is often explored in regenerative medicine and tissue engineering. However, the bioconjugation method must be carefully selected to prevent partial or full loss of activity of the biomolecule following chemical manipulation. Perfluorophenyl azide bearing a N‐hydroxysuccinimide (PFPA-NHS) active ester group is a versatile tool for UV-initiated covalent coupling of amine-containing molecules to hydrocarbon-based polymers, such as polydioxanone or polycaprolactone (PCL). This study therefore explored the feasibility of PFPA-NHS functionalisation of electrospun PCL scaffolds with model biomolecules. Protein conjugation was extensively explored using fluorescence staining and attachment studies, confirming the retention of amine coupling capability following photografting of PFPA-NHS to the PCL surface. The effect of the washing method used to remove unreacted PFPA was explored in Caco-2 cell viability studies, and it was determined that sonication washing is required to avoid cell death. A model enzyme, catalase, was then successfully attached to the surface of PCL scaffolds for potential applications in oncological photodynamic therapy. Catalase retained its enzymatic activity following attachment to the fibres and the majority of the enzyme (~60%) remained bound to the fibre after incubation in an aqueous environment for six days. The anticipated prolonged presentation and sustained release of proteins as a result of PFPA-NHS conjugation could be advantageous in progressing protein-based therapies. [ABSTRACT FROM AUTHOR]

Given the increasing interest in the use of peptide- and protein-based agents in therapeutic strategies, it is fundamental to develop delivery systems capable of preserving the biological activity of these molecules upon administration, and which can provide tuneable release profiles. Electrohydrodynamic (EHD) techniques, encompassing electrospinning and electrospraying, allow the generation of fibres and particles with high surface area-to-volume ratios, versatile architectures, and highly controllable release profiles. This review is focused on exploring the potential of different EHD methods (including blend, emulsion, and co−/multi-axial electrospinning and electrospraying) for the development of peptide and protein delivery systems. An overview of the principles of each technique is first presented, followed by a survey of the literature on the encapsulation of enzymes, growth factors, antibodies, hormones, and vaccine antigens using EHD approaches. The possibility for localised delivery using stimuli-responsive systems is also explored. Finally, the advantages and challenges with each EHD method are summarised, and the necessary steps for clinical translation and scaled-up production of electrospun and electrosprayed protein delivery systems are discussed. Unlabelled Image • Electrospinning and electrospraying can be used for protein encapsulation. • Use of biocompatible, FDA-approved materials may facilitate clinical translation. • Coaxial architectures offer advantages over blend and emulsion techniques. • Preservation of bioactivity and sustained release profiles can be achieved. • Potential for scaled-up manufacturing paves the way for product commercialisation. [ABSTRACT FROM AUTHOR]

The management of pain and inflammation arising from wounds is essential in obtaining effective healing rates. The application of a wound dressing loaded with an anti-inflammatory drug would enable both issues to be ameliorated, and the aim of this work was to fabricate such a dressing by electrospinning. Fibers comprising ethyl cellulose (EC) and poly(vinyl pyrrolidone) (PVP) loaded with naproxen (Nap) were developed to be used in the early stages of wound care. A family of PVP/EC/Nap systems was prepared by varying the PVP: EC ratio. In all cases, the products of electrospinning comprise non-woven mats of fibers which generally have smooth and cylindrical morphologies. The formulations exist as amorphous solid dispersions, and there appear to be intermolecular interactions between the three components. Adjusting the polymer ratios results in tunable drug release, and formulations have been produced which give zero-order drug release over 20 and 80 h. The fiber mats generated in this work thus have great potential to be used as dressings for the treatment of wound pain and inflammation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A modified tri-axial electrospinning with un-spinnable outer and middle fluids. • The middle fluid flow rate was varied to control the thickness of the shell. • Incrementally variable zero-order drug release profiles can be achieved. • A mathematical process-structure-performance relationship is revealed. Abstract The ability to accurately control a material's structure, and in turn its functional performance, is of crucial importance for potential applications. In this study, a new modified triaxial electrospinning process was successfully developed to allow us to precisely tune drug release from nanoscale formulations. In this process, we used two un-electrospinnable liquids as the outer and middle working fluids, with only the core solution being individually electrospinnable into fibers. The outer liquid comprised a mixture of solvents, while the middle fluid was a dilute solution of cellulose acetate (CA). The core fluid was an electrospinnable co-dissolving solution of ferulic acid (FA) and gliadin. By processing these in triaxial electrospinning, we were able to create FA-gliadin fibers coated with a thin but even and continuous coating of CA. The thickness of the CA coating could be precisely varied by adjusting the flow rate of the middle working fluid. The resultant nanofibers have linear and cylindrical morphologies with clear core-shell structures. X-ray diffraction and IR spectroscopy data verified that the fibers comprised amorphous solid dispersions, with intermolecular interactions existing between FA and gliadin. The CA coating eliminated the initial burst release seen with uncoated FA-gliadin fibers, and also led to close to zero-order release profiles which could be incrementally adjusted by varying the thickness of the coating. New process-nanostructure-performance relationships are therefore revealed, and the advanced triaxial electrospinning approach reported in this work has great potential for developing new kinds of functional nanomaterials. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A triaxial electrospinning characterized by a new detachable tri-layer spinneret. • A blank cellulose acetate layer was precisely coated on medicated nanocomposites. • A tunable sustained release profile of a poorly water-soluble drug. • A clear process-structure-performance relationship was disclosed. Abstract In this study, novel core-shell nanostructures were fabricated through a modified triaxial electrospinning process. These comprised a drug-protein nanocomposite coated with a thin cellulose acetate (CA) shell. They were generated through the simultaneous treatment of an outer solvent, an unelectrospinnable middle fluid, and an electrospinnable core solution in triaxial electrospinning. SEM and TEM results revealed that the core-shell nanofibers had linear and cylindrical morphologies with a diameter from 0.66 to 0.87 μm, and distinct core-shell structures with a shell thickness from 1.8 to 11.6 nm. The presence of a CA coating eliminated the initial burst release of ibuprofen seen from a monolithic drug-protein composite, and allowed us to precisely manipulate the drug release (for a 90% percentage) over a time period from 23.5 to 43.9 h in a tunable manner. Mathematical relationships between the processing conditions, the nanostructures produced, and their functional performance were elucidated. [ABSTRACT FROM AUTHOR]

To prepare temperature and pH dual-responsive drug delivery systems, the thermosensitive polymer poly(N-isopropylacrylamide) (PNIPAAm) was first synthesized by free-radical polymerization. It was then co-dissolved with the pH-sensitive polymer Eudragit® L100-55 (EL100-55) and processed into fibers using electrospinning. Ketoprofen (KET), a model drug, was also incorporated into the composite fibers, and fibers based on a single polymer additionally prepared. The fibers had smooth cylindrical morphologies, and no obvious phase separation could be seen. Using X-ray diffraction, KET was determined to be present in the amorphous state in the fiber matrix. FTIR spectroscopy also indicated the successful incorporation of amorphous KET in the fibers. In vitro drug release studies in media at different pH (4.5 or 7.4) or temperature (25 and 37 °C) showed that the release of KET from the blend PNIPAAm/EL100-55 fibers was dependent both on environmental temperature and pH, reflecting the dual-responsive properties of the fibers. The MTT assay was used to explore the biocompatibility of the PNIPAAm/EL100-55 composite fibers towards L929 fibroblasts. Viability was always found to be >80%, even at polymer concentrations of 100 mg/L. Therefore, the fibers prepared here could lead to the development of multi-responsive materials for drug delivery and tissue engineering. [ABSTRACT FROM AUTHOR]

In this work, a boronic acid copolymer, poly(4-vinylphenylboronic acid- co -2-(dimethylamino)ethyl methacrylate- co - n -butyl methacrylate) (pVDB) was designed for the rapid detection of bacteria based on reversible boronate ester formation with the diol-rich saccharide moieties found on bacterial membranes. Electrospun nanofibre membranes were prepared from a blend of polyacrylonitrile (PAN) and pVDB, which was synthesized by free radical polymerization. The pVDB@PAN membranes were used as fluorescent bacterial biosensors, displaying a distinct emission at 538 nm when in contact with bacteria cells. The fluorescence intensity showed a maximum intensity after 24 h of contact with Staphyloccocus aureus or Escherichia coli , and this intensity increased proportionally with the pVDB content in the electrospun membranes. When in contact with Pseudomona putida, the membranes became non-responsive within 8 h due to the rapid formation of a bacterial biofilm. This fouling phenomena blocked the membrane surface for fluorescence readings. The pVDB@PAN bionsensor allowed for the rapid detection of the early stages of bacterial colonization well before biofilm formation, which could be advantageous for the early identification of pathogenic bacteria and prevention of their spreading. [ABSTRACT FROM AUTHOR]

In this study, the thermosensitive polymer poly(di(ethylene glycol) methyl ether methacrylate) (PDEGMA) was synthesized and electrospun into fibers by blending with ethyl cellulose (EC). Fibers were additionally prepared loaded with ketoprofen (KET) as a model drug. Smooth cylindrical fibers could generally be observed by electron microscopy, although there were some beads and fused fibers visible in the KET-loaded materials. KET was found to be amorphously distributed in the fibers on the basis of X-ray diffraction data. From water contact angle measurements, it was clear that the wettability of the EC/PDEGMA systems changed as the temperature increased, with the fibers becoming markedly more hydrophobic. In vitro drug release studies showed that KET was released over a prolonged period of time with the fibers having different profiles at 25 and 37 °C, reflecting their thermosensitive properties. Furthermore, the materials were found to have good biocompatibility towards L929 fibroblasts. Thus, the fibers prepared in this work have potential as smart stimuli-responsive drug delivery systems. [ABSTRACT FROM AUTHOR]

Drug distribution within its carrier in a solid dosage form often generates a profound influence on its release profile, particularly when the physicochemical properties of the carrier are exploited to manipulate drug release behavior. In this job, two different types of distributions of a model drug ibuprofen (IBU) within a protein gliadin in their electrospun nanofibers were intentionally created. One was homogeneous distribution in the monolithic fibers fabricated using a modified coaxial process, and the other one was heterogeneous distribution in the core/shell fibers prepared through a traditional coaxial process. SEM observations clearly demonstrated the different distributions of IBU within gliadin in the two kinds of nanofibers although both of them had smooth surfaces and linear morphology. XRD results showed that IBU was amorphously distributed in the monolithic fibers, but that some IBU crystalline lattices presented in the core/shell fibers. FTIR and RM spectra suggested that gliadin had good compatibility with IBU. In vitro dissolution tests verified that the gliadin nanofibers with a heterogeneous drug distribution could provide a better sustained release profile than its counterpart in terms of initial burst release and sustained release time period. Both the fiber formation and drug-controlled release mechanisms are suggested. The present study demonstrated a concept that drug distribution with the medicated nanomaterials can be exploited as a tool to optimize the drug sustained release profile. [ABSTRACT FROM AUTHOR]

Two series of fibers containing the active ingredients acyclovir, ciprofloxacin and cyanocobalamin, and combinations of these drugs, were prepared by electrospinning. One set used the hydrophilic poly(vinylpyrrolidone) (PVP) as the filament-forming polymer, while the other used the slow-dissolving poly(ε-caprolactone) (PCL). The fibers were found to have cylindrical morphologies, although there was evidence for solvent occlusion with the PVP systems and for some drug particles in the PCL materials. The active ingredients were generally present in the amorphous physical form in the case of PVP, but evidence of crystallinity was observed with PCL. The existence of intermolecular interactions between the drugs and polymers was proven using simple molecular modeling calculations. Drug release from the various fibers was tested in a validated in vitro outflow model of the eye, and the fiber formulations found to be capable of extending drug release. We thus conclude that electrospun matrices such as those prepared in this work have potential for use as intravitreal implants. [ABSTRACT FROM AUTHOR]

A family of medicated Janus fibers that provides highly tunable biphasic drug release was fabricated using a side-by-side electrospinning process employing a Teflon-coated parallel spinneret. The coated spinneret facilitated the formation of a Janus Taylor cone and in turn high quality integrated Janus structures, which could not be reliably obtained without the Teflon coating. The fibers prepared had one side consisting of polyvinylpyrrolidone (PVP) K60 and ketoprofen, and the other of ethyl cellulose (EC) and ketoprofen. To modulate and tune drug release, PVP K10 was doped into the EC side in some cases. The fibers were linear and had flat morphologies with an indent in the center. They provide biphasic drug release, with the PVP K60 side dissolving very rapidly to deliver a loading dose of the active ingredient, and the EC side resulting in sustained release of the remaining ketoprofen. The addition of PVP K10 to the EC side was able to accelerate the second stage of release; variation in the dopant amount permitted the release rate and extent this phase to be precisely tuned. These results offer the potential to rationally design systems with highly controllable drug release profiles, which can complement natural biological rhythms and deliver maximum therapeutic effects. [ABSTRACT FROM AUTHOR]

A series of 5-fluorouracil (5-FU) loaded core/shell electrospun fibers is reported. The fibers have shells made of Eudragit S100 (ES-100), and drug-loaded cores comprising poly(vinylpyrrolidone), ethyl cellulose, ES-100, or drug alone. Monolithic 5-FU loaded ES-100 fibers were also prepared for comparison. Electron microscopy showed all the fibers to have smooth cylindrical shapes, and clear core–shell structures were visible for all samples except the monolithic fibers. 5-FU was present in the amorphous physical form in all the materials prepared. Dissolution studies showed that the ES-100 shell was not able to prevent drug release at pH 1.0, even though the polymer is completely insoluble at this pH: around 30–80% of the maximum drug release was reached after 2 h immersion at pH 1.0. These observations are ascribed to the low molecular weight of 5-FU permitting it to diffuse through pores in the ES-100 coating, and the relatively high acid solubility of the drug providing a thermodynamic impetus for this to happen. In addition, the fibers were observed to be broken or merged following 2 h at pH 1.0, giving additional escape routes for the 5-FU. [ABSTRACT FROM AUTHOR]

Highlights: [•] A Teflon-coated spinneret has been employed in electrospinning for the first time. [•] Finer polymer nanofibers were produced using the new Teflon-coated spinneret. [•] The interfacial tension between the fluid and spinneret was identified as vital to successful electrospinning. [•] A molecular mechanism rationalizing the influence of spinneret composition on electrospinning was proposed. [ABSTRACT FROM AUTHOR]

Abstract: A biocatalyst was fabricated by the covalent immobilization of the enzyme catalase on a polyacrylonitrile (PAN) based nanofibrous membrane incorporating a glycopolymer. The glycopolymer poly-(6-O-vinylsebacoyl d-glucose) [poly-OVSEG] was synthesized by a water phase precipitation homopolymerization process, and its structure was characterized by Fourier transform infrared spectroscopy (FT-IR) and NMR. Composite membranes of PAN/poly-OVSEG nanofibers containing varying amounts (50–70%) of poly-OVSEG were subsequently prepared using electrospinning. The nanofibers were studied by scanning electron microscopy (SEM) and FT-IR. Their hydrophilicity was investigated by measuring water contact angles. With increasing content of poly-OVSEG, the contact angle decreases from 65.5±2.5° to 15.2±1.1°. Catalase was immobilized on the composite nanofibrous membranes by covalent binding. The maximum catalase adsorption capacity of the polyacrylonitrile-based nanofibrous membranes was observed to be ca. 46.5mg/g. Over 50% of catalyst activity was retained and increased thermal stability observed post-immobilization (with maximum activity at pH 7.5 and 50°C). This study demonstrates the potential of using electrospun membranes to improve the thermal and storage stabilities of biological catalysts. [Copyright &y& Elsevier]

Abstract: Fast-dissolving drug delivery membranes for poorly water-soluble drugs were prepared by electrospinning using feruloyl-oleyl-glycerol (FOG) as a model drug and polyvinylpyrrolidone (PVP) K90 as a polymer matrix in a mixed solvent of chloroform/ethanol (4:1, v/v). Results from Fourier-transform infrared spectroscopy (FT-IR) illustrated good compatibility between FOG and PVP as well as a good distribution of FOG within the fibers. The morphology and diameter of the fibers were influenced by the concentration of PVP and the applied voltage. When the PVP concentration was 5% (w/v) and the applied voltage was 14kV, uniform and smooth fibers were obtained, with diameter 700–800nm. Wetting time assays confirmed fast-dissolving properties with the average dissolution time for FOG-loaded PVP fiber membranes being 2.0±1.5s. These results demonstrate the potential of electrospinning solid dispersions to improve the dissolution profile of poorly water-soluble drugs. [Copyright &y& Elsevier]

• Extracellular vesicles (EVs) were processed into fibres by electrospinning. • The EV structures are not compromised by processing. • The EV-loaded formulations retain the potency of the parent EV. Extracellular vesicles (EVs) are cell-derived bodies proven to have a wide range of therapeutic applications. To date, EVs have almost always been administered by direct injection, which is very likely to hinder their efficacy because of rapid clearance from the injection site. Here we show that EVs can be successfully processed into polymer-based fibres by electrospinning, with no loss of structure or function. [ABSTRACT FROM AUTHOR]

In this work, nanofibers based on hydrophilic poly(vinylpyrrolidone) (PVP) and hydrophobic ethyl cellulose (EC) were generated via electrospinning. A model antibiotic, ciprofloxacin (CIF), was also incorporated into the fibers. Fibers were collected on both a foil substrate and a commercial gauze, the latter in the interests of developing a smart fabric. Electron microscopy images revealed that the fibers collected on both foil and fabric were homogeneous and cylindrical. Infrared spectroscopy, X-ray diffraction and differential scanning calorimetry demonstrated that CIF was successfully loaded into the fibers and present in the amorphous physical form. In vitro drug release tests were conducted to simulate drug release from the formulations into a wound site, and as expected the hydrophilic fibers showed much faster release than their hydrophobic analogues. CIF was released through a combined mechanism of polymer erosion and drug diffusion, and the EC nanofibers displayed close to zero-order release over three days. Fibroblast cells are able to grow and proliferate on the fibers. Finally, inhibition zone assays revealed that the growth of both Gram positive and Gram negative bacteria could be effectively inhibited as a result of the presence of CIF in the fibers. There were no marked differences between the fibers collected on foil and on gauze, and electrospinning can be performed directly onto a gauze substrate to prepare a smart fabric. • Ciprofloxacin-loaded nanofibers based on hydrophilic poly(vinylpyrrolidone) and hydrophobic ethyl cellulose were prepared. • Fibers were collected on both a foil substrate and a commercial gauze. • The fibers collected on both foil and fabric were both homogeneous and cylindrical. • Both sets of fibers had excellent antibacterial properties, and the materials were highly cytocompatible. [ABSTRACT FROM AUTHOR]

• We report new electrospun fibers for the photo-chemotherapy of colon cancer. • The fibers are co-loaded with an anti-cancer drug and photosensitizer. • The fibers can target the delivery of their drug cargo to the colon. • Cytotoxicity studies show selective killing of cancerous over non-cancerous cells. In this work, we report new formulations for the combined photo-chemotherapy of colon cancer. Fibers were fabricated via coaxial-electrospinning with the intent of targeting delivery of the anti-cancer drug carmofur (CAR) and the photosensitizer rose bengal (RB) selectively to the colon site. The fibers comprised a hydroxypropyl methylcellulose (HPMC) core loaded with the active ingredients, and a pH-sensitive Eudragit L100-55 shell. The fibers were found to be homogeneous and cylindrical and have visible core-shell structures. X-ray diffraction and differential scanning calorimetry demonstrated that both CAR and RB were present in the fibers in the amorphous physical form. In vitro drug release studies showed that the fibers have the potential to selectively deliver drugs to the colon, with only 10–15 % release noted in the acidic conditions of the stomach but sustained release at pH 7.4. Cytotoxicity studies were undertaken on human dermal fibroblast (HDF) and colon cancer (Caco-2) cells, and the influence of light on cell death was also explored. The fibers loaded with CAR alone showed obvious toxicity to both cell lines, with and without the application of light. The RB-loaded fibers led to high viability (ca. 80% for both cell types) in the absence of light, but much greater toxicity was noted (30–50%) with light. The same trends were observed with the formulation containing both CAR and RB, but with lower viabilities. The RB and RB/CAR loaded systems show clear selectivity for cancerous over non-cancerous cells. Finally, mucoadhesion studies revealed there were strong adhesive forces between the rat colonic mucosa and the fibers after they had passed through an acidic environment. Such electrospun fibers thus could have potential in the development of oral therapies for colon cancer. [ABSTRACT FROM AUTHOR]