Effect of water vapor on the surface characteristics and cell compatibility of zein films.

In this study, zein microsphere films were fabricated via a solution casting method, and their surfaces were subsequently treated with a higher relative humidity. Changes in surface properties were characterized by contact-angle measurement and scanning electron microscopy (SEM). Human hepatoma cells (BEL-7402) were used as model cells to evaluate cell adhesion, spreading and proliferation on zein films before and after treatment. Additionally, the adhesion and morphologies of rat platelets on zein films were also investigated to evaluate the blood compatibility of the films. The results showed that the hydrophilicity of zein films was changed after treatment, and the surface morphology varied, gradually becoming more smooth and the microspheres in the films disappeared. As the result, the adhesion and proliferation of BEL-7402 cells were significantly improved, while HUVECs were more sensitive than BEL-7402 cells to cell-substrate interactions. Adhesion of rat platelets could be inhibited on the treated zein films. The results suggest that the synergistic actions of hydrophilic properties and micro morphologies are responsible for the cell behaviors.

Preparation of a hydrophobic polythiophene film to improve protein adsorption and proliferation of PC 12 cells.

High quality films of polythiophene with different alkyl side chains were successfully synthesized by a novel method in the presence of sodium dodecylbenzenesulonate (SDBS) under N2 atmosphere on the PTFE (polytetrafluorethylene) substrate. The as-prepared films were characterized by scanning electron microscopy (SEM), conductivity measurement, and water contact angle measurement. The morphologies of the films were homogeneous with micro-/nanostructures, and their conductivities were high enough for biomedical applications. Hydrophobicity of the films could be adjusted easily by inducing alkyl side chains with different length, which could control protein adsorption in succession. Hydrophobic polythiophene film with a long alkyl side chain had a higher ability of protein adsorption and PC 12 cell proliferation. The biocompatibility study of the synthesized films in vitro proved that the synthesized films were not cytotoxic to two cell lines used and could support cell attachment and proliferation well. Polythiophenes films prepared by in-situ deposition will be good candidates for biomedical applications.

In vivo biocompatibility and mechanical properties of porous zein scaffolds.

In our previous study, a three-dimensional zein porous scaffold with a compressive Young's modulus of up to 86.6+/-19.9 MPa and a compressive strength of up to 11.8+/-1.7 MPa was prepared, and was suitable for culture of mesenchymal stem cells (MSCs) in vitro. In this study, we examined its tissue compatibility in a rabbit subcutaneous implantation model; histological analysis revealed a good tissue response and degradability. To improve its mechanical property (especially the brittleness), the scaffolds were prepared using the club-shaped mannitol as the porogen, and stearic acid or oleic acid was added. The scaffolds obtained had an interconnected tubular pore structure, 100-380 microm in pore size, and about 80% porosity. The maximum values of the compressive strength and modulus, the tensile strength and modulus, and the flexural strength and modulus were obtained at the lowest porosity, reaching 51.81+/-8.70 and 563.8+/-23.4 MPa; 3.91+/-0.86 and 751.63+/-58.85 MPa; and 17.71+/-3.02 and 514.39+/-19.02 MPa, respectively. Addition of 15% stearic acid or 20% oleic acid did not affect the proliferation and osteogenic differentiation of MSCs, and a successful improvement of mechanical properties, especially the brittleness of the zein scaffold could be achieved.