The thermo-sensitive collagen hydrogels with semi-interpenetrating polymer network (semi-IPN) were successfully prepared by inducing type Ⅰ collagen into poly(N-isopropylacrylamide) cross-linked network.The chemical composition and pore structure of the semi-IPN gels were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM).Swelling ratio measurements and differential scanning calorimetry (DSC) were used to investigate the thermo-sensitivity of hydrogels and contact angles were studied to analyze gels surface hydrophilicity.Additionally

L929 cells' behaviors such as adhesion

proliferation and detachment were carefully studied via cell culture on the surface of PNIPAAm/CollagenⅠ semi-IPN hydrogels in vitro. The results indicated that the PNIPAAm/CollagenⅠ semi-IPN hydrogels present excellent thermo-sensitivity and biocompatibility.Cell cultures of L929 on the semi-IPN hydrogels showed better proliferation and viability than on the PNIPAAm hydrogel.By lowering temperature below the lower critical solution temperature (LCST)

L929 cells could spontaneously detach from the surface of gels.Meanwhile

the detached cells were collected for trypan blue staining and hematoxylin and eosin staining.Results showed that extracellular matrix proteins and trans-membrane proteins were hydrolysed by trypsin digestion.Cells spontaneously detached from the semi-IPN hydrogels showed higher viability than those from PNIPAAm hydrogel

which suggesting that the semi-IPN hydrogels have potential value in tissue engineering.