The TiO2 membrane supported on porous Ti planar can be used as a kind of alternative material of immunoisolation membranes, which are presently prepared by polymeric materials, in order to overcome defects of conventional immunoisolation membranes. The composite membranes were prepared by sol-gel technique with tetrabutyl titanate and the withdrawal velocity was 4 mm/s. The circle of 'dip-coating-sintering' must be repeated five times. The retention rate of proteins and flux of glucose were used to evaluate the effect of immunoisolation. The result showed that the membranes, which were sintered under 700 degrees C, could completely retain the proteins with molecular weight over 156 kDa and the retention rate of BSA exceeded 85%. At the same time, the glucose and proteins, whose molecular weight were under 45 kDa, could all freely pass the membranes according to the concentration difference of both sides. However, the retention rate of proteins first increased and subsequently decreased with the increase of sintering temperature. The membranes, which were sintered at 600 degrees C, retained more proteins than the membranes sintered at other temperatures. So a better sintering temperature, which can be used as immunoisolation membrane, is about 600 degrees C. (C) 2008 Elsevier B. V. All rights reserved.