Reviews Biofabrication with Chitosan Hyunmin Yi, ²,‡ Li-Qun Wu, ² William E. Bentley, ²,§ Reza Ghodssi, |,⊥ Gary W. Rubloff, ‡,| James N. Culver, ² and Gregory F. Payne* ,² Center for Biosystems Research, University of Maryland Biotechnology Institute, 5115 Plant Sciences Building, College Park, Maryland 20742, Department of Materials Science and Engineering, University of Maryland at College Park, College Park, Maryland 20742, Department of Chemical Engineering, University of Maryland at College Park, College Park, Maryland 20742, The Institute for Systems Research, University of Maryland at College Park, College Park, Maryland 20742, and Department of Electrical and Computer Engineering, University of Maryland at College Park, College Park, Maryland 20742 Received June 15, 2005; Revised Manuscript Received July 27, 2005 The traditional motivation for integrating biological components into microfabricated devices has been to create biosensors that meld the molecular recognition capabilities of biology with the signal processing capabilities of electronic devices. However, a different motivation is emerging; biological components are being explored to radically change how fabrication is achieved at the micro- and nanoscales. Here we review biofabrication, the use of biological materials for fabrication, and focus on three specific biofabrication approaches: directed assembly, where localized external stimuli are employed to guide assembly; enzymatic assembly, where selective biocatalysts are enlisted to build macromolecular structure; and self-assembly, where information internal to the biological material guides its own assembly. Also reviewed are recent results with the aminopolysaccharide chitosan, a material that offers a combination of properties uniquely suited for biofabrication. In particular, chitosan can be directed to assemble in response to locally applied electrical signals, and the chitosan backbone provides sites that can be employed for the assembly of proteins, nucleic acids, and virus particles. Introduction In the past, the primary reason for integrating biological components into microfabricated devices was to enlist the molecular recognition capabilities of nucleic acids, enzymes, and antibodies to perform biosensing functions. 1-3 The coupling of these biosensing components with the signal processing capabilities of microfabricated devices allowed the creation of rapid and sensitive biosensors for detection and quantification (e.g., to diagnose disease). More recently, different biological components are being examined to perform a different function: to facilitate fabrication. Interest in biofabrication (the use of biological materials for fabrica- tion) is driven by the opportunity to access a wider range of fabrication options for construction at the micro- and nanoscale. 4 Potentially, biofabrication may facilitate the fabrication of devices with reduced “minimum feature sizes”, the integration of labile biological components into high throughput testing instruments, and the generation of bio- compatible systems for implantation. Traditionally, there are three general approaches to fab- ricate micro- and nanoscale features into materials. Photo- * To whom correspondence should be addressed. Phone: (301) 405- 8389. Fax: (301) 314-9075. E-mail: payne@umbi.umd.edu. ² University of Maryland Biotechnology Institute. ‡ Department of Materials Science and Engineering, University of Maryland at College Park. § Department of Chemical Engineering, University of Maryland at College Park. | The Institute for Systems Research, University of Maryland at College Park. ⊥ Department of Electrical and Computer Engineering, University of Maryland at College Park. © Copyright 2005 by the American Chemical Society November/December 2005 Published by the American Chemical Society Volume 6, Number 6 10.1021/bm050410l CCC: $30.25 © 2005 American Chemical Society Published on Web 09/03/2005