Jie Wu,Zongmei Wu,Xuejiao Sun,Shichao Yuan,Ruling Zhang,Qingliang Lu,Yueqin Yu
Sodium alginate (SA) was combined with poly( N -isopropylacrylamide) (PNIPAAm) to prepare thermosensitive hydrogels through semi-interpenetrating polymer network (semi-IPN) and fully interpenetrating polymer network (full-IPN). The thermosensitive, swelling, mechanical, and thermal properties of pure PNIPAAm, SA/PNIPAAm semi-IPN, and Ca-alginate/PNIPAAm full-IPN hydrogels were investigated. The formation of semi-IPN and full-IPN significantly improved the hydrogels’ swelling capability and mechanical properties without altering their thermosensitivity. 5-Fluorouracil (5-Fu) was selected as a model drug to study the release behaviors of the hydrogels. It was found that in vitro controlled drug release from semi-IPN hydrogels showed an initial release burst, followed by a slower and sustained release, before reaching equilibrium. Full-IPN hydrogels showed slow and sustained release during the whole process. Temperature and pH were found to affect the rate of drug release. Ca-alginate/PNIPAAm full-IPN hydrogels have potential application as drug delivery matrices in controlled drug release.
Man Zhang,Rui Wang,Zhenqiang Shi,Xuelian Huang,Weifeng Zhao,Changsheng Zhao
A novel family of multi-responsive, tough, and reversible hydrogels were prepared by the combination of dipole-dipole interaction, hydrogen bonding interaction and slightly chemical cross-linking, using monomers of acrylonitrile, sodium allylsulfonate and itaconic acid. Reversible gel-sol transition was achieved by the flexible conversion of the dipole-dipole interactions between acrylonitrile-acrylonitrile and acrylonitrile-sodium thiocyanate, and the hydrogels could freely form desired shapes. The dipole-dipole and hydrogen bonding interactions improved the mechanical strength of the hydrogels with a compressive stress of 2.38 MPa. Meanwhile, the hydrogels sustained cyclic compressive tests with 60% strain, and exhibited excellent elastic property. The hydrogels were sensitive to pH and ionic strength, and could keep their perfect spherical structures without any obvious cracks even after immersing in strong ionic strength (or pH) solution for several reversible cycles. Furthermore, the hydrogels were recycled for environmental pollution remediation, and showed great potential to be applied in water treatments and other related fields.
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