Although three-dimensional fibroin scaffolds have been prepared with freeze-drying method, these scaffolds still cannot meet the requirements of tissue engineering. In this article, a new process is described to form fibroin-based porous scaffolds with controllable structure and morphological features. When collagen was added to fibroin solution, the viscosity of the blend solution increased because of the interaction between fibroin and collagen, and then it restrained the unwanted fibroin leaf formation in freezing process that generally appeared in the previous fibroin scaffold preparation. With methanol treatment, the fibroin/collagen scaffolds became water-stable, following the transition from random and a-helix to P-sheet conformation. The aqueous-fibroin porous scaffolds had highly homogeneous and interconnected pores with pore sizes ranging from 127 to 833 mu m, depending on the fibroin concentration. The porosity of scaffolds was > 90%, and the yield strength and modulus were up to 354 +/- 25 kPa and 30 +/- 0.1 MPa, respectively, when the blend solution, containing 20% collagen, maintained 4% fibroin concentration. Adhesion, spreading and proliferation of HepG2 cells on fibroin and fibroin/collagen blend scaffolds were also observed to investigate the biocompatibility. Scanning electron microscopy (SEM) and MTT analyses demonstrated that the adding of collagen evidently facilitated HepG2 attachment and proliferation in vitro. These new fibroin based three-dimensional scaffolds provided much more excellent properties due to the Greatly improved control of pore size, the uniform pore distribution, the hydrophility, the mechanical properties and the biocompatibility compared with those of reported three-dimensional fibroin scaffolds. (c) 2005 Elsevier Ltd. All rights reserved.