Amphiphilic silicones were prepared by the covalent incorporation of branched polyethylene oxide (PEO) via a siloxane tether. This was achieved by using six novel branched PEO-silanes with varying siloxane tether lengths and PEO molecular weight (M n ). Each PEO-silane was crosslinked via acid-catalyzed sol-gel condensation with a,x-bis(Si-OH) polydimethylsiloxane (PDMS) (M n ¼ 3000 g/mol) to yield six amphiphilic silicone films. Film surface hydrophilicity increased with siloxane tether length, particularly after exposure to an aqueous environment, indicating that the PEO segments were more readily driven to the surface. This effect was more pronounced for films prepared with PEO-silanes containing lower M n PEO segments. AFM was used to study surface reconstruction of films upon exposure to an aqueous environment. Adsorption of bovine serum albumin (BSA) and human fibrinogen (HF) proteins decreased with siloxane tether length, particularly after first exposing films to an aqueous environment. For a given siloxane tether length, relatively less BSA adsorbed onto films prepared with PEO-silanes with lower M n PEO segments whereas less HF adsorbed onto films prepared with PEO-silanes with higher M n PEO segments. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4108-4119, 2010

We report the study of the morphology, topography, and adhesion properties of internal limiting membrane (ILM) from patients with macular holes. The quantitative analysis of human ILM could provide essential information toward the improvement of existing surgical instruments for more efficient and safer surgical removal of ILM. Imaging in air revealed the presence of globular structures in most of the samples analyzed which were coupled with fibrillar structures in some of the samples. Modification of silicon nitride AFM tips with oppositely charged functional groups showed changes in adhesion force at the membrane-tip interface. Defining the surface characteristics of the human ILM is an initial step in the development of improved surgical tools that may allow nontraumatic stripping of ILM during surgery.

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Proteins are biological macromolecules which have a unique spatial conformation. Once this 3D spatial conformation is affected the protein's biological stability and activity can be severely limited. For these reasons, this investigation focuses on the effects of pre-polymeric solution components on the behavior of proteins to be encapsulated by the entrapment technique in anionic, cationic, and neutral hydrogel membranes. Equine skeletal muscle myoglobin (MMb), and equine heart myoglobin (HMb) were employed as model molecules. Three hydrogel morphologies were examined: methacrylic acid-poly(ethylene glycol) dimethacrylate (n=1000) (MAA-PEGDMA1000), dimethylaminoethyl methacrylate-poly(ethylene glycol) dimethacrylate (n=1000) (DMAEM-PEGDMA1000), and poly(ethylene glycol) (200) monomethyl ether methacrylate-poly(ethylene glycol) di-methacrylate (n=1000) (PEGDMA200-PEGDMA1000). Stability of the proteins in the pre-polymeric solution was assessed by UV-vis spectroscopy and the optimized morphologies were synthesized and the biological activity of both heme-proteins was assessed by oxidation-reduction reactions of the heme group. It was observed that while there was no displacement of the Soret bands of the proteins in the pre-polymeric solution, significant blue shifts were observed for the encapsulated proteins. Subsequent oxidation-reduction of the proteins caused shifts of the Soret bands as would be expected. However, the displaced peaks were not at their anticipated wavelengths. Other analyses will be performed on the membranes to better comprehend these results.

Bimodal imaging is utilized to characterize the topography of human tissue samples. The deposition of triamcinolone acetonide (TA) on various surfaces - including surgical human inner limiting membrane (ILM) samples and collagen fibrillar sheets - was studied. Changes in composition were well defined with bimodal imaging when TA deposition was examined on mica. TA sedimentation resulted in observable changes in ILM topography when compared to collagen fibrillar sheets. The heterogeneous chemical and topographical features of the ILM tissues promoted the TA crystallization compared to the flatter and homogeneous collagen surfaces. Higher spatial resolution was achieved by imaging ILM samples in the new bimodal imaging mode. The most apparent difference was observed in the imaging of ILM samples which had been exposed to the steroid TA. The study demonstrated the usefulness of bimodal imaging to evaluate tissue samples.