Biofabrication Based on the Enzyme-Catalyzed Coupling and Crosslinking of Pre-Formed Biopolymers

Biology provides abundant materials and inspiring mechanisms for biofabrication. Our work forcuses on the use of pre-formed biological polymers and enzymes to fabricate functionalized macromolecular structures. Biological polymers often possess many unique properties and they are renewable and biodegradable (i.e. environmentally friendly). Enzymes provide catalytic mechanism for introducing covalent bonds for the site-selective crosslinking and conjugation of these pre-formed biopolymers. In one study, we employed microbial transglutaminase (mTG)-catalyzed crosslinking of gelatin to confer mechanical function for medical adhesive applications. This biomimetic adhesive should be less expensive and simpler to use than the commercial fibrin-based medical sealants. In another study, we combined the stimuli-responsive properties of chitosan and the residue specificity of two enzymes, tyrosinase and mTG, to assemble proteins at specific device addresses. This enzymatic assembly process is reagentless and the target proteins can be controllably assembled onto electrode surfaces. In sum, we believe these two studies illustrate that biofabrication has broad range of potential applications for tissue engineering and for interfacing biology to microelectronics.