Numerical Study of Customized Artificial Cornea Shape by Hydrogel Biomaterials on Imaging and Wavefront Aberration

The blindness caused by cornea diseases has exacerbated many patients all over the world. The disadvantages of using donor corneas may cause challenges to recovering eye sight. Developing artificial corneas with biocompatibility may provide another option to recover blindness. The techniques of making individual artificial corneas that fit the biometric parameters for each person can be used to help these patients effectively. In this study, artificial corneas with different shapes (spherical, aspherical, and biconic shapes) are designed and they could be made by two different hydrogel polymers that form an interpenetrating polymer network for their excellent mechanical strength. Two designed cases for the artificial corneas are considered in the simulations: to optimize the artificial cornea for patients who still wear glasses and to assume that the patient does not wear glasses after transplanting with the optimized artificial cornea. The results show that the artificial corneas can efficiently decrease the imaging blur. Increasing asphericity of the current designed artificial corneas can be helpful for the imaging corrections. The differences in the optical performance of the optimized artificial corneas by using different materials are small. It is found that the optimized artificial cornea can reduce the high order aberrations for the second case.

The use of pectin to synthesis and characterize hydrogel (composite, grafting and blending) and study of some water retention properties

This research was conducted to purpose preparing and characterization various types of hydrogels such as blending, composite and grafting. This was done by reacting monomers such as acrylamide (A.M), methyl acrylate (M.A) and polymers. Polyvinyl Pyrrolidine (PVP) and carboxymethyl cellulose (CMC) with pectin was prepared from citrus peels. Hydrogel polymers (graft, blend and composite) were characterized using different techniques such as Fourier Transformed Infrared spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM). The results of the reactions were identical to the theoretical expectations. The study was conducted to find out some properties such as swelling in water and absorption at different temperatures 25 °C and 20 °C, and the results were shown as a (559.9%, 429.2%) and (515.2%, 363.2%) respectively.

Molecular imprinting of hydrogels : improved drug delivery vehicles

The present study aimed to characterize and evaluate the ability of two molecularly imprinted hydrogel polymers to uptake drug template molecules from solution. A copolymer of methyl methacrylate (MMA) and N, N-Dimethyl acrylamide (DMAA), and a homopolymer of 2-hydroxyethyl methacrylate (HEMA) were synthesized. Both polymer types were either molecularly imprinted (MIP) with a drug template molecule (propranolol, naproxen or timolol) or prepared without a template (non-imprinted polymer, NIP). The polymers were characterized by water content, FTIR, DSC, XRD, and SEM. With the exception of the SEM data, no differences between MIPs and NIPs were noted. Polymers were used in template re-uptake studies and their isotherms fit to Langmuir and Freundlich models. Based on the results. we conclude that the MMA-DMAA ProMIP was most successful at rebinding propranolol compared to the corresponding NIP. By changing the composition of the polymer backbone the drug uptake ability of the polymer changes drastically.

Molecular imprinting of hydrogels : improved drug delivery vehicles

The present study aimed to characterize and evaluate the ability of two molecularly imprinted hydrogel polymers to uptake drug template molecules from solution. A copolymer of methyl methacrylate (MMA) and N, N-Dimethyl acrylamide (DMAA), and a homopolymer of 2-hydroxyethyl methacrylate (HEMA) were synthesized. Both polymer types were either molecularly imprinted (MIP) with a drug template molecule (propranolol, naproxen or timolol) or prepared without a template (non-imprinted polymer, NIP). The polymers were characterized by water content, FTIR, DSC, XRD, and SEM. With the exception of the SEM data, no differences between MIPs and NIPs were noted. Polymers were used in template re-uptake studies and their isotherms fit to Langmuir and Freundlich models. Based on the results. we conclude that the MMA-DMAA ProMIP was most successful at rebinding propranolol compared to the corresponding NIP. By changing the composition of the polymer backbone the drug uptake ability of the polymer changes drastically.

Synthesis and Characterization of Silicone Contact Lenses Based on TRIS-DMA-NVP-HEMA Hydrogels

In this study, silicone-based hydrogel contact lenses were prepared by the polymerization of 3-(methacryloyloxy)propyltris(trimethylsiloxy)silane (TRIS), N,N-dimethylacrylamide (DMA), 1-vinyl-2-pyrrolidinone (NVP), and 2-hydroxyethylmethacrylate (HEMA). The properties of silicone hydrogel lenses were analyzed based on the methods such as equilibrium water content, oxygen permeability, optical transparency, contact angle, mechanical test, protein adsorption, and cell toxicity. The results showed that the TRIS content in all formulations increased the oxygen permeability and decreased the equilibrium water content, while both DMA and NVP contributed the hydrophilicity of the hydrogels. The maximum value of oxygen permeability was 74.9 barrers, corresponding to an equilibrium water content of 44.5% as well as a contact angle of 82°. Moreover, L929 fibroblasts grew on all these hydrogels, suggesting non-cytotoxicity. In general, the silicone hydrogels in this work exhibited good oxygen permeability, stiffness, and optical transparency as well as anti-protein adsorption. Hence, these silicone hydrogel polymers would be feasible for making contact lens.