Biodegradable polyvinyl alcohol/nano-hydroxyapatite composite membrane enhanced by MXene nanosheets for guided bone regeneration.

MXene, as a new category of two-dimensional nanomaterials, exhibits a promising prospect in biomedical applications due to its ultrathin structure and morphology, as well as a range of remarkable properties such as biological, chemical, electronic, and optical properties. In this work, different concentrations of MXene (M) were added to polyvinyl alcohol (PVA, P)/nano-hydroxyapatite (n-HA, H) mixed solution, and series of PVA/n-HA/MXene (PHM) composite membranes were obtained by combining sol-gel and freeze-drying processes. Morphology, chemical composition, surface, and mechanical properties of the prepared PHM membranes were characterized by various techniques. Subsequently, the swelling and degradation performances of the composite membranes were tested by swelling and degradation tests. In addition, in vitro studies like cell adhesion, cytotoxicity, proliferation, osteogenic differentiation, and antibacterial properties of MC3T3-E1 were also evaluated. The results showed that the addition of MXene could apparently improve the composite membranes' physicochemical properties, bioactivity, and osteogenic differentiation. Specially, PHM membrane had the best comprehensive properties when the concentration of MXene was set as 2.0% w/v. In a word, the addition of MXene has a positive effect on improving the mechanical properties, osteogenic induction, and antibacterial properties of PH composite membranes, and the prepared PHM composite membranes possess potential applications for guided bone regeneration.

Template-directed preparation of bovine serum albumin microporous multilayer films.

The fabrication of polymeric materials with ordered submicron-size void structures is potentially valuable for many applications such as catalysts, separation and adsorbent media. This paper reports the preparation of macroporous protein multilayer films with regular voids using silica nanospheres as templates. Both monodisperse silica colloids and highly ordered assembly silica multilayer films are used as templates to prepare microporous bovine serum albumin multilayer films with ruleless and ordered submicron-sized voids. Glutaraldehyde is used as a crosslinking agent to form a firm net-like protein film on the surface of silica templates. The microporous protein film is obtained after removing of silica templates. Compare with polymer film, protein film has good biocompatibility and biodegradability which will be beneficial to its biological applications.

Preparation and biocompatibility of BSA monolayer on silicon surface.

This paper describes a general strategy for grafting protein molecules on silicon surface by using dopamine as adhesive layer. With this method, silicon surface had been successfully modified by BSA monolayer. Fourier transform infrared spectra, X-ray photoelectron spectroscopy, contact angle analysis and atomic force microscopy confirmed the sequential grafting of initiator and protein molecules. Cell adhesion experiments with PC-12 cells showed that the obtained monolayer exhibits good biocompatibility. The corrosion resistance behavior of the polydopamine and BSA modified silicon wafers was investigated by potentiodynamic test, which indicated that the modified surfaces exhibited a better anti-corrosion capability than silicon surface. All these results must be valuable for the application of protein monolayer in biological and biomedical technology.

Antibacterial polyvinyl alcohol/bacterial cellulose/nano-silver hydrogels that effectively promote wound healing.

The lack of antibacterial properties limits the application of bacterial cellulose hydrogels in wound dressings. To overcome this deficiency, silver nanoparticles (AgNPs) were introduced as antibacterial agents into a polyvinyl alcohol (PVA)/bacterial cellulose (BC) solution. A freeze-thaw method promoted formation of PVA/BC/Ag hydrogels and improved their mechanical properties. The physicochemical and biological properties of this hydrogel were systematically characterized. Those results showed the hydrogels contained a porous three-dimensional reticulum structure and had high mechanical properties. Also, the hydrogels possessed outstanding antibacterial properties and good biocompatibilities. More importantly, it effectively repaired wound defects in mice models and wound healing reached 97.89% within 15 days, and far exceeded other groups and indicated its potential for use in wound treatment applications.

Conformational and rheological properties of bacterial cellulose sulfate.

In this study, a water-soluble bacterial cellulose sulfate (BCS) was prepared with sulfur trioxide pyridine complex (SO3· Py) in a lithium chloride (LiCl)/dimethylacetamide (DMAc) homogeneous solution system using bacterial cellulose (BC). The structural study showed that the value for the degrees of substitution of BCS was 1.23. After modification, the C-6 hydroxyl group of BC was completely substituted and the C-2 and C-3 hydroxyl groups were partially substituted. In an aqueous solution, the BCS existed as a linear polymer with irregular coil conformation, which was consistent with the findings observed using atomic force microscopy. The steady-state shear flow and dynamic viscoelasticity were systematically determined over a range of BCS concentrations (1 %-4 %, w/v) and temperature (5 °C-50 °C). Steady-state flow experiments revealed that BCS exhibited shear thinning behavior, which increased with an increase in concentration and a decrease in temperature. These observations were quantitatively demonstrated using the cross model. Moreover, based on the dynamical viscoelastic properties, we confirmed that BCS was a temperature-sensitive and weak elastic gel, which was somewhere between a dilute solution and an elastic gel. Therefore, considering the special synthetic strategy and rheological behavior, BCS might be used as a renewable material in the field of biological tissue engineering, especially in the manufacture of injectable hydrogels, cell scaffolds, and as a drug carrier.

Fabrication and biocompatibility investigation of TiO(2) films on the polymer substrates obtained via a novel and versatile route.

Titanium oxide (TiO(2)) films were successfully deposited onto the polymer substrates of polytetrafluoroethylene (PTFE), polyethylene (PE), and polyethylene terephthalate (PET), which were pre-modified with polydopamine coating (polydopamine and its coating are coded as PDA and PDAc, respectively), by a simple liquid phase deposition (LPD) process. The morphology and chemical state of the obtained TiO(2) films were characterized by field emission scanning electron microscope (FE-SEM) and X-ray photoelectron spectroscopy (XPS), respectively. Subsequently, the biocompatibility of the samples was investigated by 3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) colorimetric assay and acridine orange staining of MC-3T3 osteoblast cells, and the results demonstrated that the fabricated TiO(2) films could markedly improve the in vitro cytocompatibility. So, the presented route is anticipated to be a promising surface modification methodology to improve the practical outcome of the implanted materials for its versatility and validity.