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The past two decades have witnessed the enormous success and progress of electrospinning, as well as its broad and useful applications in pharmaceutics as a laboratory pharmaceutical nanotechnology. Everything in the past is a preface, in which the large screen opens for electrospinning and electrospun nanofibers (particularly those multiple-fluid electrospinning processes and the related multiple-chamber nanostructures) to stride into a new stage and the real commercial applications. In this commentary, four hot regions are identified for the further progress of the applications of electrospinning in pharmaceutics, in which electrospinning and its products can provide more and better services to the development of pharmaceutics. [ABSTRACT FROM AUTHOR]

Particulate matter (PM) pollution in air has imposed huge threaten and burden to public health, the global economy, and ecosystems. Air filtration, as an effective and timely strategy to remove PMs, is thus increasingly particularly crucial. Electrospun nanofibers exhibit integrated properties of nanoscale fiber diameter, small pore size, high porosity, and tunable surface wettability, and thus have gained extensive concern and hold great promise as building blocks for high-performance air filter. This review primarily focuses on the latest progress in the design principles, controllable fabrication, and application performance of electrospun nanofiber filters for high-performance air filtration. The brief overview of definition and type of PMs, filtration mechanism, and performance evaluation are first concisely given. Then, the preparation strategy, structural regulation, and application performance of electrospun nanofibrous filters categorized by passive or proactive PM trapping mechanisms are comprehensively highlighted. More importantly, the detailed application area, current challenge, and future trend of electrospun nanofiber filters are introduced and discussed. This review is expected to provide guidance for researchers to investigate the recent progress and application of electrospun nanofibers for air filtration. [Display omitted] • Mechanism, design, and fabrication of nanofibrous air filters by electrospinning are reviewed. • Electrospun nanofiber filters with various structures and surface properties are highlighted. • Properties and performances for current applications of nanofiber filters are provided. • Future trend and challenges of electrospun nanofiber filters are discussed. [ABSTRACT FROM AUTHOR]

Hypromellose (HPMC)-based hydrophilic composites (HCs) used for rapid dissolution of ferulic acid (FA) were investigated. Electrospun and casting HCs were prepared from a solution containing HPMC, FA, and polyethylene glycol. Ethanol was used as sheath fluid during coaxial processes, and the effects of its flow rates on the Taylor cone and straight fluid jet were investigated. The morphology, component state, hydrophilicity, and drug dissolution rate of the HCs were characterized. Results demonstrated that all HCs were amorphous materials, and their components were compatible. However, the dissolution rate of electrospun HCs was 10 times faster than that of casting HCs. The smaller the diameters of electrospun HCs were, the better their performances were. The mechanism of electrospun HCs was suggested. By utilizing modified coaxial electrospinning and combinations of drug carriers, new types of HPMC-based HCs can provide an alternative approach for the effective delivery of poorly water-soluble drugs. [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]

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: This study investigates the use of a modified coaxial electrospinning process in the production of drug-loaded cellulose acetate (CA) nanofibers. With CA employed as a filament-forming matrix and ketoprofen (KET) as an active pharmaceutical ingredient, modified coaxial processes using sheath fluids comprising only mixed solvents were undertaken. With a sheath-to-core flow rate ratio of 0.2:1, the nanofibers prepared from the coaxial process had a smaller average diameter, narrower size distribution, more uniform structures, and smoother surface morphologies than those generated from single fluid electrospinning. In addition, the coaxial fibers provided a better zero-order drug release profile. The use of a sheath solvent means that the core jet is subjected to electrical drawing for a longer period, facilitating homogeneous core jet solidification and retarding the formation of wrinkles on the surface of the nanofibers. This modified coaxial electrospinning protocol allows the systematic fabrication of functional polymer nanofibers with improved quality. [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]

Abstract: Third generation solid dispersions (SDs) of ferulic acid (FA) in composite nanofibers were prepared using electrospinning. The spinning liquids involved co-dissolving solutions of FA, polyvinylpyrrolidone (PVP), sodium dodecyl sulfate (SDS) and sucralose in 75% ethanol aqueous solutions. FESEM observations showed that the nanofibers were assembled in a homogeneous web structure that had a smooth cross-section and surface with an average diameter of 254±32nm. Results from DSC and XRD suggested that FA, SDS and sucralose were distributed in the PVP fibers in an amorphous manner and this is due to their compatibility resulting through a second-order interactions, as demonstrated by ATR-FTIR spectra. In vitro dissolution and permeation tests showed that the nanofiber-based SDs could release all the contained FA within 1min and had a 13-fold higher permeation rate across sublingual mucosa compared to crude FA particles. The casting films have the same compositions as the nanofibers and belong to the third generation SDs, they gave the same solubility of FA as the nanofibers, and also exhibited a much faster dissolution rate than pure FA particles. It felt that electrospinning can be taken to prepare new generation SDs with structural characteristics that enhancing absorbance of poorly soluble drugs. [ABSTRACT FROM AUTHOR]

Abstract: An elevated temperature electrospinning process was developed for the preparation of drug-loaded polyacrylonitrile (PAN) ultrafine fibers. An additional apparatus for maintaining the electrospinning temperature at a high constant value was fitted on the syringe pump. Acyclovir (ACY)-loaded PAN fibers could be prepared from the co-dissolving dimethyl sulfoxide solutions of PAN and ACY at 80°C. As the temperature increased, the viscosities and the surface tensions of the co-dissolving solutions decreased, whereas conductivities increased, which can account for the improved electrospinning ability of the solutions. 1H NMR analysis demonstrated that chemical integrity of ACY was maintained during the elevated temperature electrospinning process. The prepared ACY-loaded PAN ultrafine fibers had a smooth surface and uniform structure with no bead-on-a-string configurations. 94% of the fiber diameters fell within the range of 400–700nm. The X-ray diffractograms and DSC results demonstrated that almost all the ACY was able to be distributed in the PAN fiber matrix in an amorphous status. The FTIR spectra demonstrated that PAN and ACY had sufficient compatibility due to hydrogen bonding. In vitro dissolution tests exhibited that the fibers could provide sustained drug release profiles over a time period of 16h. The study demonstrates that an elevated temperature electrospinning process is able to broaden the processing window and enabling the preparation of new types of functional fibers with high quality. [Copyright &y& Elsevier]

Abstract: Novel doughnut-shaped multi-layered drug delivery devices (DDDs) were developed with local variations of the drug and release-retardant material for providing linear release profiles. Based on computer-aided design models, different DDDs containing acetaminophen as a model drug, hydroxypropyl methylcellulose as matrix and ethyl cellulose (EC) as a release-retardant material were prepared automatically using a three-dimensional printing (3DP) system. In vitro dissolution assays demonstrated that all the 3DP DDDs had with different diameters, heights, concentrations of EC and central hole diameters were able to give linear release profiles. Morphological and erosion studies showed that acetaminophen was released through a simultaneous surface erosion process involving the outer peripheries and inner apertures. The barrier layers on both bases of DDDs had good adhesion strength with the drug-contained regions and offered consistent release retardation for the whole duration of the dissolution process. The release time periods of the DDDs were dependent on the annular thicknesses or the passes of binder solution containing a release-retardant material. The dosage of the DDD can be adjusted independently by changing the heights of the DDDs. Thus, 3DP is capable of offering novel strategies for developing DDDs with complex design features for desired drug release profiles. [Copyright &y& Elsevier]

Three-dimensional printing (3DP) is a rapid prototyping (RP) technology. Prototyping involves constructing specific layers that uses powder processing and liquid binding materials. Reports in the literature have highlighted the many advantages of the 3DP system over other processes in enhancing pharmaceutical applications, these include new methods in design, development, manufacture, and commercialization of various types of solid dosage forms. For example, 3DP technology is flexible in that it can be used in applications linked to linear drug delivery systems (DDS), colon-targeted DDS, oral fast disintegrating DDS, floating DDS, time controlled, and pulse release DDS as well as dosage form with multiphase release properties and implantable DDS. In addition 3DP can also provide solutions for resolving difficulties relating to the delivery of poorly water-soluble drugs, peptides and proteins, preparation of DDS for high toxic and potent drugs and controlled-release of multidrugs in a single dosage forms. Due to its flexible and highly reproducible manufacturing process, 3DP has some advantages over conventional compressing and other RP technologies in fabricating solid DDS. This enables 3DP to be further developed for use in pharmaceutics applications. However, there are some problems that limit the further applications of the system, such as the selections of suitable excipients and the pharmacotechnical properties of 3DP products. Further developments are therefore needed to overcome these issues where 3DP systems can be successfully combined with conventional pharmaceutics. Here we present an overview and the potential 3DP in the development of new drug delivery systems. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:3666–3690, 2008 [ABSTRACT FROM AUTHOR]