Study On Synthesis Of Thermo-sensitive Hydrogel By Radiation And Cell Culture And Desorption With It

Poly(N-isopropylacrylamide) hydrogel is a thermo-sensitive hydrogel which can changevolume at a critical temperature. As a new type of intelligent material, which has importantapplication in drug release, separate field, enzymatic adsorption, cell cultivation and so on, ithas been paid much attention. The rapid development of Tissue Engineering has a lot ofachievements. But there also exists many challenges in some aspects. Seed cell is thefoundation of tissue engineering. Conventional enzymatic degradation has damages on functionand heredity of cell during cell passage. This problem has always feazed researchers. Yamadaetc. makes use of the thermo-sensitivity of N-isopropylacrylamide synthesizing athermo-sensitive material on which cell can place themselves and grow above the lower criticalsolution temperature(LCSY), and desorp when temperature is below LCST. This changes themethod of conventional enzymatic degradation which used to make cell fallen. In this article,P(AAm-g-NIPAAm) which is prepared to be used as a new intelligent material on tissueengineering is synthesized from NIPAAm and PAAm hydrogel by radiation. We will make surewhether it can be used on cell culture and can make cell desorp automatically by decreasetemperature to below its LCST in this article.1. Poly(N-isopropylacrylamide) of different radiation intensity and monomer concentration issynthesized by radiation. We measure its LCST and it is about 33℃. Influence of radiationintensity and monomer concentration on its viscosity average molecular weight is alsoobserved. And the results show that molecular weight of PNIPAAm increases with increaseof radiation dose and monomer concentration. We also researched cell toxicity of PNIPAAmby the method of direct touch and get the conclusion that cell toxicity of PNIPAAm is grade0.2. P(AAm-co-NIPAAm) hydrogel of different monomer proportion is synthesized by radiation.Its thermo-sensitivity is researched by DSC and the method of swelling ratio respectively.The results show that LCST increase with the increase of content of AAm in thecomposition of monomer. The LCST of P(AAm-co-NIPAAm) exceeds 100℃when molarration of AAm and NIPAAm is 1:1. In addition, swelling ratio of P(AAm-co-NIPAAm)increases with the increase of content of AAm in the composition of monomer.3. P(AAm-g-NIPAAm) hydrogel of different monomer proportion is synthesized by radiation.Its composition, structure and thermo-sensitivity are studied. Its LCST is 31℃despite ofdifferent monomer proportion which is obtained by DSC and 721 spectrophotometerrespectively. Its swelling ratio increases with increase of AAm in the monomer proportion.characteristic peak -CONH- and-CH(CH₃)₂ of NIPAAm appear on infrared spectrum and ¹H NMR. We also measured its contact angle and the results show transition of hydrophilicand hydrophobic happens when temperature changes.4. In experiment of cell culture, we plant epithelia on the film of P(AAm-g-NIPAAm)hydrogel. We can see cell grow well on the material from Inverted microscope. Whenmaking environment temperature fall to 25℃, cell desorp from material automatically withsurging slightly. We can protect functions of cell from damaging by enzymatic degradationby this method.