Abstract
Purpose: :
We are continuing our search for developing polymeric hydrogels that form in situ as potential vitreous substitutes and lens nanocomposites. With this goal in mind, in this study we synthesized and characterize anionic poly(sodium methacrylate) based materials with respect to number average molecular weight (MWn), refractive index (RI), polydispersity (PD), storage and elastic modulus and transparency.
Methods: :
Poly(methacrylic acid) based hydrogels were synthesized in N,N-dimethylformamide, as described by Gao et al., PMSE 2007, 97,572. 2-hydroxyethyl methacrylamide was incorporated to allow for subsequent hydrophobic modification of the copolymer. Reversible hydrogels were prepared by incorporation of bis-methacryloyl cystamine crosslinker at 2 and 5%. Polymers were characterized using a Viscotek multi-detection system in conjunction with GPC. Polymers were neutralized with NaOH and placed in phosphate buffered saline. Storage and elastic modulus was determined using a Vilastic-3 oscillatory capillary tube rheometer. RI was obtained from an Abbe Refractometer.
Results: :
Measured parameters are displayed in Table 1. Values are given for 1.5%w/w formulations for all polymers. Storage and loss modulus values were measured at 10% shear strain and a frequency of 2Hz.
Conclusions: :
This is our first analysis of poly (sodium methacrylate). Advantageous features of this polymer includes: 1) it has high viscosity at low concentrations; 2) poly(sodium methacrylate) is relatively biocompatible; 3) it has adhesive properties; 4) it mimics biological proteins and polysaccharides, which have ionic components. Transparency issues with certain combinations may require the use of poly(sodium methacrylate) as a copolymer with methacrylamides, and reduction in the amount of the hydrophobic moieties.
Keywords: vitreous substitutes • retinal adhesion • intraocular lens