Electrospinning of PCL/PVP blends for tissue engineering scaffolds.

Currently, one of the main drawbacks of using poly(ε-caprolactone) in the biomedical and pharmaceutical fields is represented by its low biodegradation rate. To overcome this limitation, electrospinning of PCL blended with a water-soluble poly(N-vinyl-2-pyrrolidone) was used to fabricate scaffolds with tunable fiber surface morphology and controllable degradation rates. Electrospun scaffolds revealed a highly immiscible blend state. The incorporated PVP phase was dispersed as inclusions within the electrospun fibers, and then easily extracted by immersing them in cell culture medium, exhibiting nanoporosity on the fiber surface. As a striking result, nanoporosity facilitated not only fiber biodegradation rates, but also improved cell attachment and spreading on the blend electrospun scaffolds. The present findings demonstrate that simultaneous electrospinning technique for PCL with water-soluble PVP provides important insights for successful tuning biodegradation rate for the PCL electrospun scaffolds but not limited to expand other high valuable biocompatible polymers for the future biomedical applications, ranging from tissue regeneration to controlled drug delivery.

Low-temperature ZnO atomic layer deposition on biotemplates: flexible photocatalytic ZnO structures from eggshell membranes.

Macroporous ZnO membranes with a strong photocatalytic effect and high mechanical flexibility were prepared from inner shell membranes (ISM) of avian eggshells as templates after performing low-temperature ZnO atomic layer deposition (ALD). In order to evaluate the potential merits and general applicability of the ZnO structures, a comparative study of two membranes with coatings of either TiO2 or ZnO, processed under similar conditions, was performed. The study includes crystallographic features, mechanical and thermal stability and bactericidal efficiency. Both, the ZnO and the TiO2 coated membranes clearly exhibited bactericidal effects as well as mechanical flexibility and thermal stability even at relatively high temperatures. The ZnO membranes, even though prepared at fairly low temperatures (approximately 100 degrees C), exhibited polycrystalline phases and showed a good bactericidal efficiency as well as higher mechanical flexibility than the TiO2 coated membranes. This study shows the benefits of low-temperature ZnO ALD i.e., the thermally non-destructive nature, which preserves the mechanical stability and the native morphology of the templates used, together with an added functionality, i.e. the bactericidal effect.

Electrospun PVA/HAp nanocomposite nanofibers: biomimetics of mineralized hard tissues at a lower level of complexity.

Based on the biomimetic approaches the present work describes a straightforward technique to mimic not only the architecture (the morphology) but also the chemistry (the composition) of the lowest level of the hierarchical organization of bone. This technique uses an electrospinning (ES) process with polyvinyl alcohol (PVA) and hydroxyapatite (HAp) nanoparticles. To determine morphology, crystalline structures and thermal properties of the resulting electrospun fibers with the pure PVA and PVA/HAp nanocomposite (NC) before electrospinning various techniques were employed, including transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). In addition, FT-IR spectroscopy was carried out to analyze the complex structural changes upon undergoing electrospinning as well as interactions between HAp and PVA. The morphological and crystallographic investigations revealed that the rod-like HAp nanoparticles exhibit a nanoporous morphology and are embedded within the electrospun fibers. A large number of HAp nanorods are preferentially oriented parallel to the longitudinal direction of the electrospun PVA fibers, which closely resemble the naturally mineralized hard tissues of bones. Due to abundant OH groups present in PVA and HAp nanorods, they strongly interact via hydrogen bonding within the electrospun PVA/HAp NC fibers, which results in improved thermal properties. The unique physiochemical features of the electrospun PVA/HAp NC nanofibers prepared by the ES process will open up a wide variety of future applications related to hard tissue replacement and regeneration (bone and dentin), not limited to coating implants.