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Emerging treatment strategies for retinal degeneration involve replacing lost photoreceptors using supportive scaffolds to ensure cells survive the implantation process. While many design aspects of these scaffolds, including material chemistry and microstructural cues, have been studied in depth, a full set of design constraints has yet to be established. For example, while known to be important in other tissues and systems, the influence of mechanical properties on surgical handling has not been quantified. In this study, photocrosslinked poly(ethylene glycol) dimethacrylate (PEGDMA) was used as a model polymer to study the effects of scaffold modulus (stiffness) on surgical handling, independent of material chemistry. This was achieved by modulating the molecular weight and concentrations of the PEGDMA in various prepolymer solutions. Scaffold modulus of each formulation was measured using photo-rheology, which enabled the collection of real-time polymerization data. In addition to measuring scaffold mechanical properties, this approach gave insight on polymerization kinetics, which were used to determine the polymerization time required for each sample. Scaffold handling characteristics were qualitatively evaluated using both in vitro and ex vivo trials that mimicked the surgical procedure. In these trials, scaffolds with shear moduli above 35 kPa performed satisfactorily, while those below this limit performed poorly. In other words, scaffolds below this modulus were too fragile for reliable transplantation. To better compare these results with literature values, the compressive modulus was measured for select samples, with the lower shear modulus limit corresponding to roughly 115 kPa compressive modulus. While an upper mechanical property limit was not readily apparent from these results, there was increased variability in surgical handling performance in samples with shear moduli above 800 kPa. Overall, the knowledge presented here provides important groundwork for future studies designed to examine additional retinal scaffold considerations, including the effect of scaffold mechanical properties on retinal progenitor cell fate., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Surface properties of poly(oxyethylene)s with alkyl thioether side chains (CH 3 -nTE; n=carbon atoms in the side chain) were investigated. CH 3 -nTEs having shorter side chains (n=6, 8, 10) did not have ordered structures, while those with longer chains (n=12, 14) showed well-ordered, lamellar structures with side chain crystalline domains. Accordingly, CH 3 -12TE and CH 3 -14TE film surfaces were much more enriched with hydrophobic alkyl side chains than CH 3 -8TE and CH 3 -10TE surfaces. However, CH 3 -12TE and CH 3 -14TE films had smaller water contact angles (≈114°) than CH 3 -8TE and CH 3 -10TE films (>130°). This unexpected behavior is ascribed to the formation of very rough CH 3 -8TE and CH 3 -10TE film surfaces (R rms >100nm) on contact with water. The CH 3 -10TE/poly(methyl methacrylate) (PMMA) surfaces also showed high water contact angles (>125°), even with low CH 3 -10TE content (30wt%), because the CH 3 -10TE moiety roughened the surfaces. Furthermore, ultra-hydrophobic sticky behavior was observed for CH 3 -nTEs (n=8, 10) and CH 3 -10TE/PMMA surfaces., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Connexin 43 (Cx43) downregulation promotes apoptosis in retinal vascular cells of diabetic animal models; however, its relevance to human diabetic retinopathy has not been established. In this study, we investigated whether diabetes alters Cx43 expression and promotes retinal vascular lesions in human retinas. Diabetic human eyes (aged 64-94 years) and non-diabetic human eyes (aged 61-90 years) were analyzed in this study. Retinal protein samples and retinal capillary networks were assessed for Cx43 level by Western blot (WB) analysis and immunostaining. In parallel, retinal capillary networks were stained with hematoxylin and periodic acid Schiff to determine the extent of pericyte loss (PL) and acellular capillaries (AC) in these retinas. Cx43 protein expression was significantly reduced in the diabetic retinas compared to non-diabetic retinas as indicated by WB analysis (81 ± 11% of control). Additionally, a significant decrease in the number of Cx43 plaques per unit length of vessel was observed in the diabetic retinas compared to those of non-diabetic retinas (62 ± 10% of control; p < 0.005). Importantly, a strong inverse relationship was noted between Cx43 expression and the relative number of AC (r = -0.89; p < 0.0005), and between Cx43 expression and number of pericyte loss (r = -0.88; p < 0.0005). Overall, these results show that Cx43 expression is reduced in the human diabetic retinas and Cx43 reduction is associated with increased vascular cell death. These findings suggest that diabetes decreases retinal Cx43 expression and that the development of PL and AC is associated with reduced Cx43 expression in human diabetic retinopathy., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The blend surfaces of poly[oxy(n-decylsulfonylmethyl)ethylene] (CH(3)-10SE) and poly (3-hexylthiophene) (P3HT) with different weight ratios were prepared by spin coating the polymer solution mixtures. In this study, their surface properties such as surface morphology, chemical composition, molecular structure, and wettability were systematically studied and correlated with liquid crystal (LC) alignment behaviors on the blend films. Therefore, we found that CH(3)-10SE part with a well-ordered side chain structure predominantly affects the both of wettability and LC alignment behavior of the blend films while there was no clear association between the wettability and the LC alignment behavior., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Silver-perfluorodecanethiolate complexes having superhydrophobic, antifouling, antibacterial properties were prepared by a reaction of silver nitrate with perfluorodecanethiol. When the silver nitrate to perfluorodecanethiol molar ratio was 1/2, silver-perfluorodecanethiolate complexes having hierarchical micro-/nano-sized wire shapes were obtained, and they showed superhydrophobic and antifouling properties. After UV irradiation, silver nanoparticles were generated on the wires and exhibited antibacterial properties., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Poly(2-hydroxyethyl methacrylate) derivatives with amphiphilic side chains composed of polar ester and non-polar alkyl groups (PHEMA#C, #=9, 11, 13, 15, and 17), where # is the number of carbon atoms in the alkyl side groups, were synthesized. In this paper, the influence of ester and alkyl groups on the molecular structure and wettability of the polymers were studied through varying # in the alkyl side groups. PHEMA#Cs with relatively longer alkyl side groups (#≥15) show bilayer lamellar structures with well aligned side chains giving rise to the very low surface energies, calculated from advancing contact angles, in the range of 22.7-22.8 mN/m. In contrast, PHEMA#Cs with shorter alkyl side groups with #≤13 have disordered structures on the polymer surfaces and stick-slip behavior was observed when water was used as the test liquid for the advancing contact angle measurements. Furthermore, the alignment behavior of nematic liquid crystal, 5CB on the PHEMA#C films could be correlated with the molecular structure and wettability of the polymers., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Phase-separated surfaces of blends of polystyrene (PS) and well ordered comb-like polymer, poly[(oxy(decylsulfonylmethyl)ethylene)] (CH(3)-10SE), were prepared by spin casting polymer mixtures. Various surface morphologies, such as holes, islands, connected islands and pillars, were prepared by changing the blend compositions. Due to the influence of the CH(3)-10SE domain with a well ordered molecular conformation, a very low energy surface (≈22mN/m) was created, which is close to the value of the pure polymer (≈20mN/m), even when the blends contained only 20wt.% of the pure polymer. Furthermore, by selective etching the PS domain in the blend surfaces, the advancing contact angles of water and n-hexadecane were highly increased from 113.5° and 43.2° for the pure CH(3)-10SE surface to 133.3° and 67.2° for the CH(3)-10SE structural surfaces with holes prepared using the solvent etching method, respectively. The result of the water advancing contact angles measured on the samples immersed in water over 20days showed that the film stability of CH(3)-10SE could be improved considerably by even adding small amounts of PS., (Copyright © 2010 Elsevier Inc. All rights reserved.)

The surface properties of comb-like polymer blends of poly(oxyethylene)s having CH(3)-terminated and CF(3)-terminated alkylsulfonylmethyl side chains were studied. These side chains were found to be well oriented on the surface of the blends, while being phase separated, forming various surface morphologies composed of holes, islands, or connected islands, because of their immiscibility resulting from their different polarities. The domain size of each polymer on the blend surface was found to be almost linearly proportional to the bulk compositions of the mixture, and the CF(3)-terminated alkylsulfonylmethyl side chain domains were found to be located in the lower region of the surface. The polar CF(3)-terminal groups in the lower regions were deemed to control the surface properties, because the contact angles and stick-slip behaviors of the blends containing more than 40 mol% of poly(oxyethylene) with CF(3)-terminated side chains were almost identical., (2009 Elsevier Inc. All rights reserved.)