Development Of Silicone Contact Lenses Based On Zwitterionic Materials

The nonspecific protein adsorption on the surfaces is an important problem for biomaterial application, such as contact lenses. The contact lense users are easy to get clinical symptoms such as dry eyes and eye infections which are caused by a lack of oxygen providing for cornea cells and protein adsorption on the lense surfaces from tears. Silicone rubbers are widely applied in the contact lense materials due to its high oxygen permeability. However, this kind of materials need to be modified to improve their surface hydrophilicity. The zwitterionic materials such as poly(2-methacry-loyloxyethyl phosphorylcholine) (pMPC), poly(carboxybetaine) (pCB) and poly(sulfobetaine) (pSB) are confirmed to have the potential for application to silicone contact lenses because of their excellent nonfouling properties. In this research, a novel biocompatible silicone rubber are developed based on the zwitterionic materials. The main contents and conclusions are shown as following:1. As hydrolysis precursor, carboxybetaine ester (CB-ester) analogue was synthesized at first. The brush polymers pCMM with different polymerization degrees were synthesized via two steps:atom free radical polymerization and acylation reaction. The novel biocompatible silicones comprising different weight proportion of pCMM, bis-α,ω-(methacryloxypropyl) polydimethylsiloxane (Macromer) and 3-methacryloxypropyltris-(trimethylsiloxy)silane (TRIS) were developed via photo-polymerisation, which exhibited super-hydrophilicity and low nonspecific protein adsorption via the interfacial hydrolysis of CB-ester.2. TRIS monomer was introduced in the process of the synthesis of pCMM to get pCMM-TRIS in order to improve the optical transparency of the silicones. A new silicone was made by pCMM-TRIS instead of pCMM and showed higher optical transparency.3. The study shows that the surface hydrophilicity and the resistant to nonspecific protein adsorption increased with an increase in the pCMM-TRIS unit composition. The novel silicone exhibits a significant reduction in relative protein adsorption to 5.0%. The optical transparency, thermal stability and mechanical property of the silicones are suitable for the use of contact lenses materials. In addition, the biocompatibility and the resistant to bacteria adhesion are excellent. Thus, we confirms that it has great potential for contact lenses and other applications.