Surface plasma treatment of chitosan films is a widely used technique to control a variety of their properties, such as permeability, hemostatic activity and ability to support cell adhesion, proliferation and growth. Among other factors to be controlled, the chemical structure of initial chitosan is rarely taken into consideration. This work is aimed to highlight this factor by the example of low pressure direct-current discharge of various chitosan film samples. Contact angle measurements, X-ray photoelectron spectroscopy and scanning electron microscopy revealed differences in the film surface properties of the initial and plasma-treated films. The effect of the plasma treatment on cell viability of L929 mouse fibroblasts was studied by MTT-assay.
The article discusses the results of mathematical and experimental simulation of the impact of atomic oxygen of the Earth's upper atmosphere on carbon and boron nitride nanotubes, graphene, hexagonal boron nitride sheets, and graphene nanoribbons, as well as composites based on polymer matrices with fillers in the form of nanosized particles of various types.
213 eposition of thin layers of natural materials onto the surface of hydrophobic synthetic polymers is used for enhancement of their biocompatibility. For example, the surface of matrices for regenerative medicine is frequently coated with chitosan, the deacetylation product of the natural polysaccharide chitin [1][2][3]. As a rule, a chitosan thin film is applied by casting a solu tion on a polymer surface after its preliminary modifi cation, for example, by plasma treating to create active sites responsible for high adhesion of the film to the substrate [4-6].There are reports in the literature on the gas phase deposition of polytetrafluoroethylene (PTFE) on pol ished single crystal silicon substrates by irradiation of a polymer sample (target) with an electron beam of a 0.1-2.5 keV electron energy [7,8]. It was shown that the first layers of the deposited film had the same com position and structure as those of parent PTFE, whereas a considerable amount of double bonds and oxygen containing groups in the structure of the film was observed at its thickness of ≥0.3 µm. This method was also used for the deposition of low density poly ethylene thin films on silicon and PTFE substrates [9]. It was found that the nature of the substrate has a noticeable effect on the crystallinity and chemical stricture of the films.In this study, we first used the electron beam sput ter deposition of a polymer in a vacuum for preparing chitosan thin films on a poly(L,L lactide).Chitosan poly[(1 → 4) 2 amino 2 deoxy β D glucose] derived by solid state synthesis from crab shell chitin [10] was used. The chitosan molecular weight was 60 kDa and the degree of acetylation was 0.1 according to potentiometric titration and elemen tal analysis data. The target for electron beam sputter ing was prepared by compressing a chitosan powder at a pressure of 0.1 MPa to have the target disk of 15 mm in diameter and 5 mm in thickness.The substrates were films of poly(L,L lactide) (PLLA), a biodegradable, biocompatible, thermo plastic aliphatic polyester that is widely used for the manufacturing of resorbable medical articles, such as surgical sutures and pins. Semicrystalline PLLA with a molecular weight of 160 kDa and mp 165°C (available from Sigma) was used without further purification. Film samples of ~100 µm in thickness were prepared by casting a 5% solution in CH 2 Cl 2 into Petri dishes. The films were dried at room temperature under equi librium conditions until complete dryness (~2 days).A chitosan film was applied by the electron beam sputter deposition of the polymer in a vacuum from the active gas phase on a PLLA substrate using the procedure and setup detailed in [8]. The electron source was an electron gun with a heated filament cathode, which made it possible to form beams with a current density of 5-100 A/m 2 , an electron energy of 0.5-2 keV, and a cross section of (5-10) × 10 -4 m 2 . The initial pressure of residual gas in the vacuum chamber was ∼10 -3 Pa, and the substrate surface tem perature was ~300 K. The current density du...
The aim of the study was to fabricate and characterize composite macroporous hydrogels based on a hyaluronic acid/chitosan (Hyal/Ch) polyelectrolyte complex (PEC) loaded with homogeneously distributed hydroxyapatite nanoparticles (nHAp), and to evaluate them in vitro using mouse fibroblasts (L929), osteoblast-like cells (HOS) and human mesenchymal stromal cells (hMSC). Hydrogel morphology as a function of the hydroxyapatite nanoparticle content was studied using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The mean pore size in the Hyal/Ch hydrogel was 204 ± 25 μm. The entrapment of nHAp (1 and 5 wt. %) into the Hyal/Ch hydrogel led to a mean pore size decrease (94 ± 2 and 77 ± 9 μm, relatively). Swelling ratio and weight loss of the hydrogels in various aqueous media were found to increase with an enhancement of a medium ionic strength. Cell morphology and localization within the hydrogels was studied by CLSM. Cell viability depended upon the nHAp content and was evaluated by MTT-assay after 7 days of cultivation in the hydrogels. An increase of the hydroxyapatite nanoparticles loading in a range of 1–10 wt. % resulted in an enhancement of cell growth and proliferation for all hydrogels. Maximum cell viability was obtained in case of the Hyal/Ch/nHAp-10 sample (10 wt. % nHAp), while a minimal cell number was found for the Hyal/Ch/nHAp-1 hydrogel (1 wt. % nHAp). Thus, the proposed simple original technique and the design of PEC hydrogels could be promising for tissue engineering, in particular for bone tissue repair.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.