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ABSTRACT Aligned, uniform fiber matrixes are highly desirable in numerous engineering and physical science applications. Here, modified electrospinning (ES) deposition substrates (paired and in parallel) are explored to achieve rapid preparation of multiple topographies. Three ES substrates with well-defined geometries (rectangular, concave, and E-shaped) were investigated (arranged in parallel) for their impact on fiber size, morphology, orientation, and cell behavior. The results indicate fiber alignment and orientation can be improved and modulated based on the substrate geometry. In addition, altering the interdistance space between various parallel substrates has a clear impact on fiber diameter size and alignment (random, aligned, and perpendicular orientation). Electric field simulations based on substrate geometries show greater probable regions of aligned electric field vectors and distribution, which indicates the most likely deposition attributes of electrospun PCL fibers. Fibrous PCL membranes were biocompatible, and cell growth and guidance were along the fiber path, with evidence of branching at intersecting fibers for multiaxial fibrous topographies. These findings show that the substrate geometry can be optimized to effectively assemble multiaxial layered and well-aligned fibers in a controlled fashion, which is ideal to support several application developments dependent on fiber topography, integrity, and morphology. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44823. [ABSTRACT FROM AUTHOR]

Diffusion‐weighted magnetic resonance imaging (MRI) is an emerging noninvasive imaging modality. In this study, highly aligned, uniform, nanoporous, hollow polycaprolactone fibers were successfully synthesized in a single step to mimic the axon bundle structure in human white matter. Their porous nature, morphology, and physicochemical properties were carefully studied with respect to their suitability as a phantom material for brain imaging. The aligned fibrous bundles were then arranged into specific angles (30 and 90°), scanned, and evaluated with high‐resolution MRI fiber tractography. Diffusion tensor imaging and the tractography of fibers of five different structures at three temperatures were acquired and compared. Furthermore, an integrated brain phantom created from a combination of agar gel and aligned fibrous bundles was also fabricated and analyzed. The results demonstrate the excellent ability of the fibers to mimic the axonal bundles of brain white matter. The fibrous bundles were well mixed in the common agar phantom while retaining their fibrous configuration; this demonstrated their potential as brain white matter phantoms. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47617. [ABSTRACT FROM AUTHOR]

Fibrous technologies (such as membranes, films, patches and filters) and their enabling engineering platforms have gained considerable interest over the last decade. In this study, novel fibrous constructs from a unique engineering platform were developed based on hybrid electrohydrodynamic (EHD) technology; incorporating functional and bioactive materials within random and aligned fibrous formulation geometries. Complex constructs were engineered using 3D printing (polycaprolactone, PCL, for sustained delivery) and electrospinning (polyvinylpyrrolidone, PVP, for rapid release) in an intercalating material layer-by-layer format using a side-by-side technological approach. Here, structure generation proceeded with deposition of ordered PCL fibers enabling well-defined void size and overall dimension, after which randomly spun PVP fibers formed a construct overcoat (as a membrane). Differences between polymer dissolution rate, hydrophilicity, mechanical properties and functional material hosting (and linked external auxiliary magnetic field trigger) provided opportunities to modulate antibiotic drug (tetracycline hydrochloride, TE-HCl) release. In vitro cell studies using human umbilical vein blood vessel cell line demonstrated device biocompatibility and Escherichia Coli (E. coli) was selected to demonstrate anti-bacterial function. Overall, a new hybrid engineering platform to prepare customizable and exciting multi-faceted drug release constructs is elucidated. [ABSTRACT FROM AUTHOR]

Multi-faceted technological advances in fiber science have proven to be invaluable in several emerging biomaterial and biomedical engineering applications. In the last decade, notable fiber engineering advances have been demonstrated ranging from co-axial flows (for micron and nano-scaled layering), non-concentric flows (for Janus composites) and even 3D printing (for controlled alignment). The ES process is however limited, both for commercial impact (low production rates) and also in its facile capability to deliver reliable mimicry of numerous biological tissues which comprise blended and aligned fibers (e.g. tendons and ligaments). In the technological advance demonstrated here, a combinatorial multi-compartment centrifugal electrospinning (CMCCE) system is developed and demonstrated. A proof-of-concept enabling multiple formulation solution hosting (including combinatorial grading) in a single centrifugal electrospinning system (CES) comprising one spinneret is shown. Using this process, controlled blending and tuning of resulting fibrous membrane properties (contact angle and active release behavior) via aligned and phased fiber mat composition is demonstrated. In addition, the CMCCE process is capable of replicating production rates of recently developed centrifugal electrospinning systems (∼120 g/h), while potentially permitting better mimicry of naturally occurring fibrous tissue blends. It is envisaged the advance in technology will be ideally suited to engineer synthetic fibrous biomaterials with greater host surface replication and will fulfil production rate requirements for the industrial sector. [ABSTRACT FROM AUTHOR]

In this study, a relatively facile porous magnetic hollow fiber engineering electrospinning method is demonstrated, which modulates fiber morphology based on secondary solvents (at variable temperatures). To demonstrate this, polycaprolactone (PCL) polymer and iron oxide nanoparticles (NPs) were used as the fibrous composite matrix. Fiber pore size increased with increasing immersed secondary solvent temperature. By contouring the surface morphology ( via modulation of secondary collection solvents) of hollow magnetic fibers, drug (ketoconazole) release kinetics from spun mats were tuned. Furthermore, applying an external AC magnetic field to NP embedded porous fibers enhanced drug release. These findings are promising for alternative engineering, tuning and controlling fiber morphology and drug release behavior. [ABSTRACT FROM AUTHOR]

Multi-compartment fibers with well-defined regions and functional media hosting potential provide co-encapsulation opportunities for a variety of bio-molecules, drugs and even nutrients. In this research, fibers possessing multiple compartments were prepared using the single-step electrospinning method and a modified non-concentric multi-needle. Polyvinyl pyrrolidone (PVP) was used as the fiber shell material, while ketoconazole (KCZ, model drug) and Sudan Red (model probe) were encapsulated as two separate segments running along the fiber length. Multi-compartment fiber morphology and structure were examined using optical and electron microscopy. The effect of flow rate on fiber morphology was also investigated and the release of encapsulated KCZ and Sudan Red was examined using UV spectroscopy. The results present an efficient and promising method to engineer multi-compartment fibers in a single step for several biomedical applications in lieu . [ABSTRACT FROM AUTHOR]

Recent advances in fiber technology and engineering, for nano- and micro-meter scaled materials, have focused largely on developments surrounding the electrospinning (ES) technique. Although this process enables the engineering of complex fibrous structures; the inability to yield industrial scale production through existing ES techniques becomes a bottle-neck and critical feature. Furthermore, in several advanced engineering remits (such as healthcare) the role of fiber alignment, layering and morphology is also paramount. In this study the development of a enhanced spinneret device for the up-scaled production of aligned fibers is demonstrated. Compared to conventional centrifugal electrospinning (CES) techniques, a relatively greater production rate of fibers is achieved at reduced rotation speeds and also excludes the use of needles during the process. The impact of experimental process parameters such as rotation speed (60–90 rpm), working distance (9–14 cm) and solution concentration (15–30 w/v%) on resulting fiber properties were investigated using commercial polymeric drug delivery excipient polyvinyl pyrrolidone (PVP). Mass production of fibers is demonstrated and the impact of specifically aligned ultrafine drug-fiber matrices on drug release behavior is shown. For this, the antibiotic tetracycline hydrogen chloride was spun alongside PVP (5 w/w%) as the matrix material. The spinneret device provides an enhanced approach for active embedded fiber production on a scale favorable to industry (120 g/h) when using optimized process parameters (70 rpm and 15 kV for the four-pore system). Furthermore, the in-situ method permits control on fiber alignment and overall mat thickness providing tailored fabrication for specific applications or drug dosage requirements (e.g. active dissolution behavior for fibrous drug delivery systems). [ABSTRACT FROM AUTHOR]

Several active encapsulation technologies using polymeric matrix systems for food preservation have been developed in the last decade. In this study, the microencapsulation of rose hip seed oil (REO) in to a zein prolamine (ZP) fiber matrix via the coaxial electrospinning technique is studied. The morphological features of core-sheath REO encapsulated ZP fibers were modulated through process parameters (e.g. active and polymer solution concentration, applied voltage and media flow rate). The ZP solution concentration (outer needle) was found to be critical for REO loading capacity (LC) and encapsulation efficiency (EE). The optimal LC and EE of REO in ZP matrix was 12.24% and 90.16%, respectively, and were achieved using a ZP concentration of 35 w/v%. Food packaging potential was evaluated using peeled and segmented fruits (bananas and cumquats). The findings demonstrate a facile packaging route to improve food sustainability and reduce waste. [ABSTRACT FROM AUTHOR]

Fiber modulation in-situ during the electrospinning process via enveloping liquid manipulation is a relatively un-explored process parameter. In this study, one-step control of fiber diameter and morphology are demonstrated using three liquids (ethanol, dimethyl silicone oil and mineral oil) serving as the outer-flowing medium during the co-axial process. Poly-caprolactone (PCL) fibers with various surface morphologies (porous, rough and smooth) and mean diameters (2–8 µm) were prepared. The results clearly show the modified enveloping liquid coaxial electrospinning approach permits fiber size regulation, hydrophobic enhancement and surface topography variation. This development has potential to meet requirements of polymeric fibers with micro and nano-patterned surface topographies, for biomedical and pharmaceutical applications, in a single step. [ABSTRACT FROM AUTHOR]

Hollow magnetic fibers for trigger based drug release were synthesized using one-step co-axial electrospinning (COX-ES). This was achieved by encapsulating the antifungal active ‘ketoconazole’ (KCZ) and iron oxide (Fe 3 O 4 ) nanoparticles (NPs) in composite form within the core shell polymeric matrix material (polycaprolactone, PCL) during the COX-ES process. Dimethyl silicone oil was used as the inner core (liquid) of co-flowing solutions, which subsequently perfused out of the two-phase electrospun microstructures to form hollow fibers. Resulting drug-loaded magnetic hollow fibers were characterized using optical microscopy, scanning electron microscopy and Fourier Transform Infra-Red. The tensile strength and magnetization properties of composite fibers were also assessed. KCZ drug concentration in electrospinning solutions strongly influenced resulting fiber morphology, drug loading efficiency and release. Expedited drug release during a slow-sustained phase was demonstrated through the application of an auxiliary magnetic field. Variations in tensile strength (∼1.3–6.3 MPa) were due to composite fiber components compromising polymer chain integrity. In-vitro cell studies (using human cervical carcinoma cell lines) demonstrated fiber biocompatibility. The present study demonstrates the potential application of magnetic hollow fibers for controlled treatment of fungal infections and antimicrobial indications. [ABSTRACT FROM AUTHOR]