Stereolithography-assisted fabrication of hydrogels of carboxybetaine methacrylamide (CBMAA) and a α,ω-methacrylate poly(d,l-lactide-block-ethylene glycol-block- d,l-lactide) (MA-PDLLA-PEG-PDLLA-MA) telechelic triblock macromer is presented. This technique allows printing complex structures with gyroid interconnected porosity possessing extremely high specific area. Hydrogels are characterized by infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and laser scanning confocal microscopy (LSCM). The copolymerization with zwitterionic comonomer leads hydrogels with high equilibrium water content (EWC), up to 700% while maintaining mechanical robustness. The introduction of carboxybetaine yields excellent resistance to nonspecific protein adsorption while providing a facile way for specific biofunctionalization with a model protein, fluorescein isothiocyanate labeled bovine serum albumin (BSA). The homogeneous protein immobilization across the hydrogel pores prove the accessibility to the innermost pore volumes. The remarkably low protein adsorption combined with the interconnected nature of the porosity allowing fast diffusion of nutrient and waste product and the mimicry of bone trabecular, makes the hydrogels presented here highly attractive for tissue engineering.

Department of Biomaterials Science and Technology Group Technical Medical Centre University of Twente P O Box 217 7500 AE Enschede The Netherlands W J Kolff Institute Department of Biomedical Engineering University Medical Center Groningen University of Groningen Antonius Deusinglaan 1 9713 AV Groningen The Netherlands

DWI Leibniz Institute for Interactive Materials and Institute of Technical and Macromolecular Chemistry RWTH Aachen University Forckenbeckstraße 50 52074 Aachen Germany

Institute Charles Gerhardt Montpellier CNRS University of Montpellier ENSCM 34095 Montpellier Cedex 5 France

Institute of Macromolecular Chemistry Academy of Sciences of the Czech Republic v v i Heyrovsky sq 2 Prague 162 06 Czech Republic