Blending chitosan-g-poly(caprolactone) with poly(caprolactone) by electrospinning to produce functional fiber mats for tissue engineering applications

Use of electrospun fiber mats for tissue engineering applications has become increasingly prominent. One of the most important polymers in research, poly(ε-caprolactone) (PCL), however, lacks biological performance, easy access to modifications and cellular recognition sites. To improve these properties and to enable further modifications, PCL was blended with chitosan grafted with PCL (CS-g-PCL) and subsequently processed via electrospinning. In this way, chitosan was enriched at the fiber's surface presenting cationic amino groups. The fiber mats were analyzed by various techniques such as scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), and X-ray photoelectron spectroscopy (XPS). Furthermore, analyzing thermal properties and crystallinity, showed that an increased content of CS-g-PCL in blend composition leads to a higher overall crystallinity in produced fiber mats. Blending CS-g-PCL into PCL significantly increased initial cellular attachment and proliferation as well as cell vitality, while maintaining adequate mechanical properties, fiber diameter, and interstitial volume. As proof of principle for easy access to further modification, fluorescently labeled alginate (Alg-FA) was attached to the fiber's surface and verified by CLSM. Hence, blending CS-g-PCL with PCL can overcome an inherent weakness of PCL and create bioactive implants for tissue engineering applications. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48650. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc

Polyelectrolyte blend multilayer films: Surface morphology, wettability, and protein adsorption characteristics

We report the influence of polyelectrolyte (PE) multilayer films prepared from poly(styrene sulfonate) - poly(acrylic acid) (PSS-PAA) blends, deposited in alternation with poly(allylamine hydrochloride) (PAH), on film wettability and the adsorption behavior of the protein immunoglobulin G (IgG). Variations in the chemical composition of the PAH/(PSS-PAA) multilayer films, controlled by the PSS/PAA blend ratio in the dipping solutions, were used to systematically control film thickness, surface morphology, surface wettability, and IgG adsorption. Spectroscopic ellipsometry measurements indicate that increasing the PSS content in the blend solutions results in a systematic decrease in film thickness. Increasing the PSS content in the blend solutions also leads to a reduction in film surface roughness (as measured by atomic force microscopy), with a corresponding increase in surface hydrophobicity. Advancing contact angles (θ) range from 7° for PAH/PAA films through to 53° for PAH/PSS films. X-ray photoelectron spectroscopy measurements indicate that the increase in film hydrophobicity is due to an increase in PSS concentration at the film surface. In addition, the influence of added electrolyte in the PE solutions was investigated. Adsorption from PE solutions containing added salt favors PSS adsorption and results in more hydrophobic films. The amount of IgG adsorbed on the multilayer films systematically increased on films assembled from blends with increasing PSS content, suggesting strong interactions between PSS in the multilayer films and IgG. Hence, multilayer films prepared from blended PE solutions can be used to tune film thickness and composition, as well as wetting and protein adsorption characteristics