Study On The Synthesis And The Property Of PH-sensitive Hydrogels

In this paper, a series of pH-sensitive hydrogels were prepared by UV-initiated freeradical polymerization. The swelling behavior and pH sensitivity of the hydrogelswere studied in detail.At first, we introduced BSA into the P(MAA-EG) hydrogel to formP(MAA-EG)-BSA semi-interpenetrating network The swelling behavior and pHsensitivity of the hydrogels were studied in detail. Due to the combined greatbiocompatibility and biodegradability of BSA, and the pH sensitivity of theP(MAA-EG) copolymer, the obtained P(MAA-EG)-BSA SIPN might bepH-sensitive and partly-biodegradable, and it might have great potential to be used intargeted drug delivery systems. The obtained hydrogels were characterized by1H-NMR and FTIR. Swelling behavior in different aqueous media andpH-responsivity of the hydrogels were studied in detail too. With increase in pH from1.7 to 7.7, swelling ratio of the hydrogels increased then. The effect Effect of MAAcontent, PEG content,BSA content,Bis content and PEG's macromolecular weighton the swelling behavior of hydrogels was studied in detail.Secondly, a novel biodegradable and pH-sensitive hydrogel P(CL/EG-MAA))based on polycaprolactone, poly(ethylene glycol) and methylacrylic acid(MAA), was prepared by UV-initiated free radical polymerization. The obtained hydrogel was characterized by ~1H-NMR and FTIR. Swelling behavior in differentaqueous media and pH-responsivity of the hydrogels were studied in detail too. Theeffect Effect of MAA PCL content, PEG content, Bis content and PEG'smacromolecular weight on the swelling behavior ofhydrogels was studied in detail.Thirdly, biodegradable and pH-sensitive P(CL/EG -MAA) hydrogel based onpolycaprolactone, poly(ethylene glycol) and methylacrylic acid (MAA), wasprepared by UV-initiated free radical polymerization. The obtained hydrogel wascharacterized by ~1H-NMR and FTIR. The acute toxiciy tests and histopathologicalstudy were performed in BALB/c mice. In acute oral toxicity test, mice were orallyadministered with a total 15g/kg body weight (b.w.) of P(CL/EG -MAA) hydrogels,and were observed continuously for 14 days. For histopathologic study, samplesincluding heart, liver, lung, kidneys, spleen, stomach, and intestine, werehistochemical prepared and stained, with hematoxylin-esin for histopathologicexamination. No mortality or significant signs of acute toxicity was observed duringthe whole observation period, and no macroscopic alteration was found in the organs.Histopathological analysis of various organs also did not show any significantpathological changes. Thus, the maximal tolerance dose of P(CL/EG-MAA)hydrogels was calculated to be higher than 15g/kg b.w. in BALB/c mice. Itwas suggested that the studied P(CL/EG -MAA)hydrogel in this paper werenon-toxic after acute oral administration and it might be a promising candidate as anovel oral drug carrier.At last, a new kind of biodegradable pH sensitive hydrogels P (CL-MAA-EG)were successfully synthesized by UV-initiated free radical polymerization. Theobtained hydrogels were characterized by ~1H-NMR and FTIR. Swelling behavior indifferent aqueous media and pH-responsivity of the hydrogels were studied in detailtoo. With increase in pH from 1.2 to 7.2, swelling ratio of the hydrogels increasedthen. The morphology was observed by scanning electron microscopy (SEM), andthe hydrolytic degradation behavior was also investigated in this paper.