Abstract
A kind of chemically cross-linked pH-sensitive hydrogels based on methoxyl poly(ethylene glycol)-poly(caprolactone)-acryloyl chloride (MPEG-PCL-AC, PECA), poly(ethylene glycol) methyl ether methacrylate (MPEGMA, MEG), N,N-methylenebisacrylamide (BIS), and itaconic acid (IA) were prepared without using any organic solvent by heat-initiated free radical method. The obtained macromonomers and hydrogels were characterized by 1H NMR and FT-IR, respectively. Morphology study of hydrogels was also investigated in this paper, and it showed that the hydrogels had good pH-sensitivity. The acute toxicity test and histopathological study were conducted in BALB/c mice. The results indicated that the maximum tolerance dose of the hydrogel was higher than 10000 mg/kg body weight. No morality or signs of toxicity were observed during the whole 7-day observation period. Compared to the control groups, there were no important adverse effects in the variables of hematology routine test and serum chemistry analysis both in male or female treatment group. Histopathological study also did not show any significant lesions, including heart, liver, lung, spleen, kidney, stomach, intestine, and testis. All the results demonstrated that this hydrogel was nontoxic after gavage. Thus, the hydrogel might be the biocompatible potential candidate for oral drug delivery system.
Highlights
Hydrogels are networks which can swell in water and hold a large mount of water while maintaining their three-dimensional structure
The MPEG-PCL copolymer was synthesized by ring-opening polymerization of ε-caprolactone initiated by MPEG using tin (II) 2-ethylhexanoate as catalyst [29, 30]
The MPEGPCL copolymer was synthesized by ring-opening polymerization of ε-caprolactone initiated by MPEG
Summary
Hydrogels are networks which can swell in water and hold a large mount of water while maintaining their three-dimensional structure. The environment-sensitive hydrogels which are called “intelligent” or “smart” hydrogels have attracted increasing attention, because they can show a sudden or gradual change in their dynamic and equilibrium properties with the changes of ambient conditions such as temperature [1, 2], pH [3,4,5], and ionic strength [6] They might have great potential in targeted drug delivery system, on-off switches for modulated drug delivery, artificial organs, and immobilization of enzyme due to their biocompatibility and resemblance to biological tissues [7,8,9,10,11]. The pH-sensitive hydrogels could improve drug efficacy and reduce the side effects [22,23,24]
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