Synthesis And Properties Of The Smart PHEMA Based Hydrogels

As one of the traditional biological based materials,2-hydroxyethyl methacrylate (HEMA), with high hydrophilicity and good biocompatibility, has been widely applied in biomedical field. However, the application of pHEMA hydrogels is always restricted owing to the limited water intake and poor biological stimulus response. In this paper, In this paper, we prepared three different smart pHEMA based hydrogels, and characterized their physicochemical properties in detail. The whole work was mainly composed of the following three aspects:1.A novel semi-interpenetrating pHEMA based polyelectrolyte hydrogel (p(HEMA-co-METAC)/PEG) was prepared by copolymerizing HEMA with the cationic monomer 2-methacryloyloxyethyltrimethyl ammonium chloride (METAC) in the presence of polyethylene glycol (PEG) with different content and molecular weight (MW 4000 and 400). The chemical structure of the gels was confirmed by FT-IR spectroscopy, morphology study was performed by SEM, thermal stability was revealed by TGA, and the mechanical properties were determined by electronic universal testing machine. Swelling studies showed introduction of cationic monomer METAC led to high water content, and the obvious salt and pH sensitive properties were observed which proved the smart behavior of the semi-IPNs gels. In addition, the effect of temperature and some important biological solution on swelling behavior were reported. Cytotoxicity test demonstrated that synthesized gels owned satisfactory cytocompatibility and were convenient for the application as biomaterials. Finally, the weak bovine serum albumin (BSA) adsorption on semi-IPNs by introducing METAC and controlling the content of PEG in gels demonstrated that they were of good protein resistance effect in biomedical applications.2. Novel ampholytic pHEMA based hydrogels (HMA) were prepared by copolymerizing HEMA with the cationic monomer METAC and anionic monomer 2-acrylamido-2-methylpropane-sulphonic acid (AMPS) in different mole ratios. The chemical structure of the ampholytic HMA gels was confirmed by FT-IR analysis, morphology study was performed by SEM, and thermal stability was revealed by TGA. Swelling studies showed that the ampholytic HMA gels with different mole ratio of anionic/cationic monomer (rAc) played an important role in swelling behavior, and the obvious salt and pH sensitive properties were observed which proved the smart behavior of gels. In addition, the swelling ratio (SR) of gels in different neutral solutions had no significant distinction when ionic strength kept the same, and the swelling behavior also revealed the temperature-independence property of gels. The cytotoxicity study in vitro showed if properly controlling the content of AMPS in gels, we could obtain the ampholytic HMA gels with good cytocompatible, which are convenient for the applications as biomaterials.3. By copolymerizing HEMA with METAC and acrylic acid (AA) in different mole ratios, we obtained a new ampholytic pHEMA based HMAA gels. The chemical structure of the ampholytic HMAA gels was confirmed by FT-IR analysis, morphology study was performed by SEM, and thermal stability was revealed by TGA. Swelling studies showed that besides rAc, different kind of ionic monomer also had an important effect on the SR of the ampholytic HMAA gels. The obvious salt and pH sensitive properties were observed which proved the smart behavior of gels, and the SR of gels in different neutral solutions had no significant distinction when ionic strength kept the same. In addition, the ampholytic HMAA gels showed certain temperature-independence property which is quite different from previous studies. The results of cytotoxicity study in vitro showed most ampholytic HMA gels were with good cytocompatible and convenient for the applications as biomaterials. In addition, the obvious cytotoxicity of gels HAA and HMAA3 may be due to the interaction between cationic and the overmuch anionic groups which resulted in the change of physical environment pH, so cells can not survive.