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Co-axial electrospraying and electrospinning are versatile electrohydrodynamic (EHD) techniques that can be used to encapsulate a variety of materials in the form of polymeric particles and fibres via a one step process. The successful production of uniform encapsulated products in co-axial EHD (CEHD) processing depends on multiple parameters including solution concentration, applied voltage and needle capillary diameter. Although many studies have been conducted to investigate the effects of these parameters, there has been very limited research on how the axial displacement between the two needle tips affects the final products formed. Hence the purpose of this study was to adjust the positioning of the inner needle such that its tip extends beyond, is level with or resides inside that of the outer needle and to thus determine the most effective arrangement for controlling product size, uniformity and/or yield. Core–shell particles were prepared using two polymers, poly(lactic-co-glycolic)acid (PLGA) as the shell and polymethylsilsesquioxane (PMSQ) as the core and core–shell fibres using PMSQ as the shell and a volatile liquid, perfluorohexane (PFH) as the core. The products formed were analyzed by optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). After analysis, it was concluded that the most effective arrangement for generating both particles and fibres with the optimal combination of size, uniformity and yield was to have the inner needle 2 mm inside the outer needle. This allows for formation of a stable cone–jet and successful encapsulation of the inner liquid within the outer liquid, before the outer stable cone–jet forms. The corresponding collected product diameter and percentage of products in which material was successfully encapsulated were found to be 0.6 ± 0.1 μm and 85 ± 3% respectively for particles and 9 ± 1 μm and 92 ± 2% for fibres.

The electrohydrodynamic (EHD) technique has traditionally been confined to the bench-top. Recently, a portable EHD device was constructed that allows the process to be applied in a much more flexible and versatile manner. In this article, the effect of electrode and collector height on the fibers generated by EHD and wound-dressing forming capabilities of the device tested on different types of simulated wound morphologies were investigated. Dressings were also fabricated on living tissue to investigate jet behavior and product morphology. The EHD device was found to be capable of controlled deposition of micrometer-sized poly(D,L-lactide-co-glycolide) acid fibers that can form an opaque, waterproof wound dressing on human skin within a few minutes with excellent adherence.

Electrohydrodynamic (EHD) processing has attracted substantial interest in the technological and pharmaceutical sectors in recent years. Given the complexity of the process, exploring new ideas for EHD electrospraying and electrospinning delivery is a challenge. In this article, the design, construction and testing of a portable handheld EHD multi-needle device are described to produce multifunctional particles and fibers. Solid and encapsulated polymer particles and fibers were generated in order to study the performance of the device. The intrinsic properties of the feed solution/suspension and the processing conditions were adjusted to ensure robustness of the process and give uniform and reproducible products, with diameters ranging from the sub-micrometer scale to a few micrometers. These products have a broad range of applications in many advanced industrial sectors e.g. drug delivery systems, wound dressing patches, low calorie food products and cosmetics. © 2012 Elsevier B.V.

Encapsulation of materials in fibres with a well-controlled size distribution is an important application of the electrospinning technique. This study investigates the effect of key parameters of the coaxial electrospinning process including flow rate, applied voltage and polymer concentration on the efficient encapsulation and size distribution of perfluorohexane (PFH) in polymethylsilsesquioxane (PMSQ) microfibres. Perfluorohexane can be exchanged for a drug via a simple diffusion-controlled process. By altering the polymer concentration and processing parameters, PMSQ microfibres with different diameters, PFH core size and core-to-core distance were obtained. It was found that PFH-encapsulated fibres with a diameter between 8 and 15 μm can be prepared when the PMSQ concentration is kept between 55–70 wt%. The PFH regions (cores) encapsulated in the fibre are uniformly distributed and of size 5–14 μm. The core-to-core distance significantly increased from 4 μm to 22 μm when the applied voltage was increased from 8 kV to 11 kV. These results indicate a potential strategy for controlling fibre diameter, core size and core-to-core distance by using coaxial electrospinning as the forming procedure and thus this work will help to advance biomedical engineering applications, for example, drug delivery, scaffolding for tissue engineering and wound dressing.

PURPOSE: To produce electrospun polymeric fibrous wound dressing patches that can release the antibiotic drug amoxicillin in a controlled manner. METHODS: Poly(D,L-lactide-co-glycolide) acid (PLGA) fibrous dressings with entrapped amoxicillin were produced by electrospinning. The morphology and successful entrapment of amoxicillin in the PLGA fibrous dressings were validated by scanning electron microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy. The rate of drug release from the dressing patches was measured in various media for a period of 21 days using UV spectroscopy. RESULTS: PLGA fibres entrapping amoxicillin were collected for 300 s and then cut to form square patches with an average weight of 55 mg. Each dressing patch contained ~2 mg of amoxicillin. The mean fibre diameter was 2.2 ± 0.4 μm. The drug release from the PLGA dressings was found to be different for each medium during the 21-day release period with the highest and lowest concentration of drug released observed when the dressings were immersed in simulated body fluid (SBF) and phosphate buffered saline (PBS), respectively. CONCLUSIONS: The release profiles obtained in this study and the well-established biocompatibility of PLGA indicate that the fibre-based patches with entrapped amoxicillin fabricated in this work are very well suited for applications in wound healing and infection control.