Role of Curing Temperature of Poly(Glycerol Sebacate) Substrates on Protein-Cell Interaction and Early Cell Adhesion.

A novel procedure to obtain smooth, continuous polymeric surfaces from poly(glycerol sebacate) (PGS) has been developed with the spin-coating technique. This method proves useful for separating the effect of the chemistry and morphology of the networks (that can be obtained by varying the synthesis parameters) on cell-protein-substrate interactions from that of structural variables. Solutions of the PGS pre-polymer can be spin-coated, to then be cured.

Amphipathic Substrates Based on Crosslinker-Free Poly(ε-Caprolactone):Poly(2-Hydroxyethyl Methacrylate) Semi-Interpenetrated Networks Promote Serum Protein Adsorption.

A simple procedure has been developed to synthesize uncrosslinked soluble poly(hydroxyethyl methacrylate) (PHEMA) gels, ready for use in a subsequent fabrication stage. The presence of 75 wt % methanol (MetOH) or dimethylformamide (DMF) impedes lateral hydroxyl-hydroxyl hydrogen bonds between PHEMA macromers to form during their solution polymerization at 60 °C, up to 24 h. These gels remain soluble when properly stored in closed containers under cold conditions and, when needed, yield by solvent evaporation spontaneous physically-crosslinked PHEMA adapted to the mould used.

Biological activity of the substrate-induced fibronectin network: insight into the third dimension through electrospun fibers.

Fibronectin (FN) fibrillogenesis is a cell-mediated process involving integrin activation that results in conformational changes of FN molecules and the organization of actin cytoskeleton. A similar process can be induced by some chemistries in the absence of cells, e.g.

Microcomputed tomography and microfinite element modeling for evaluating polymer scaffolds architecture and their mechanical properties.

Detailed knowledge of the porous architecture of synthetic scaffolds for tissue engineering, their mechanical properties, and their interrelationship was obtained in a nondestructive manner. Image analysis of microcomputed tomography (microCT) sections of different scaffolds was done. The three-dimensional (3D) reconstruction of the scaffold allows one to quantify scaffold porosity, including pore size, pore distribution, and struts' thickness.

Fibrinogen patterns and activity on substrates with tailored hydroxy density.

The influence of the surface fraction of OH groups on fibrinogen (FG) adsorption is investigated in copolymers of ethyl acrylate and hydroxy ethylacrylate. The amount of adsorbed FG, quantified by western-blotting combined with image analysis of the corresponding bands, decreases as the hydrophilicity of the substrate increases. The influence of substrate wettability on FG conformation and distribution is observed by atomic force microscopy (AFM).

Substrate-induced assembly of fibronectin into networks: influence of surface chemistry and effect on osteoblast adhesion.

The influence of surface chemistry-substrates with controlled surface density of -OH groups-on fibronectin (FN) conformation and distribution is directly observed by atomic force microscopy (AFM). FN fibrillogenesis, which is known to be a process triggered by interaction with integrins, is shown in our case to be induced by the substrate (in absence of cells), which is able to enhance FN-FN interactions leading to the formation of a protein network on the material surface. This phenomenon depends both on surface chemistry and protein concentration.

Fibronectin activity on substrates with controlled --OH density.

Adhesion of human fibroblast to a family of fibronectin (FN) coated model substrates consisting of copolymers of ethyl acrylate and hydroxyl ethylacrylate in different ratios to obtain a controlled surface density of --OH groups was investigated. Cell adhesion and spreading surprisingly decreased as the fraction of --OH groups on the surface increased. AFM studies of FN conformation revealed formation of a protein network on the more hydrophobic surfaces.

Human chondrocyte morphology, its dedifferentiation, and fibronectin conformation on different PLLA microtopographies.

Surfaces of poly(L-lactic acid) (PLLA) of well-defined microtopography were prepared by making use of the semicrystalline character of PLLA. Different thermal treatments before isothermal crystallization (which include nucleation steps) permit to obtain a controlled number of simultaneously growing spherulites, which, in the end, modulate the topography at the microscale. Four qualitatively different surfaces were prepared.

Three-dimensional nanocomposite scaffolds with ordered cylindrical orthogonal pores.

A silica reinforcement can improve the mechanical properties of hydrogels in the rubbery state. A method to prepare a scaffold with a well-ordered array of cylindrical pores is presented in this work, which yields a scaffold with a biphasic matrix of a hybrid nanocomposite: the hydrogel poly(2-hydroxyethyl acrylate) (PHEA) and a silica network obtained by an acid catalyzed sol-gel process of tetraethoxysilane (TEOS). As porogenic template of the scaffold stacked layers of commercial polyamide 6 fabrics were used, which were compressed and sintered.

Substrate chemistry-dependent conformations of single laminin molecules on polymer surfaces are revealed by the phase signal of atomic force microscopy.

The conformation of single laminin molecules adsorbed on synthetic substrates is directly observed making use of the phase magnitude in tapping mode atomic force microscopy (AFM). With AFM, it is not possible to differentiate the proteins on the substrate if use is made of the height signal, since the roughness of the material becomes of the same order of magnitude as the adsorbed protein, typically 10 nm height. This work shows how AFM can be exploited to reveal protein conformation on polymer materials.