title: Protein-engineered biomaterials: nanoscale mimics of the extracellular matrix.
abstract: BACKGROUND
  Traditional materials used as in vitro cell culture substrates are rigid and flat surfaces that lack the exquisite nano- and micro-scale features of the in vivo extracellular environment. While these surfaces can be coated with harvested extracellular matrix (ECM) proteins to partially recapitulate the bio-instructive nature of the ECM, these harvested proteins often exhibit large batch-to-batch variability and can be difficult to customize for specific biological studies. In contrast, recombinant protein technology can be utilized to synthesize families of 3 dimensional protein-engineered biomaterials that are cyto-compatible, reproducible, and fully customizable.
  
  
  METHODS
  Here we describe a modular design strategy to synthesize protein-engineered biomaterials that fuse together multiple repeats of nanoscale peptide design motifs into full-length engineered ECM mimics.
  
  
  CONCLUSIONS
  Due to the molecular-level precision of recombinant protein synthesis, these biomaterials can be tailored to include a variety of bio-instructional ligands at specified densities, to exhibit mechanical properties that match those of native tissue, and to include proteolytic target sites that enable cell-triggered scaffold remodeling. Furthermore, these biomaterials can be processed into forms that are injectable for minimally-invasive delivery or spatially patterned to enable the release of multiple drugs with distinct release kinetics.
  
  
  CONCLUSIONS
  Given the reproducibility and flexibility of these protein-engineered biomaterials, they are ideal substrates for reductionist biological studies of cell-matrix interactions, for in vitro models of physiological processes, and for bio-instructive scaffolds in regenerative medicine therapies. This article is part of a Special Issue entitled Nanotechnologies - Emerging Applications in Biomedicine.
authors.affiliation: Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305-4045, USA.
authors.forename: Nicole H
authors.initials: NH
authors.lastname: Romano
authors.forename: Debanti
authors.initials: D
authors.lastname: Sengupta
authors.forename: Cindy
authors.initials: C
authors.lastname: Chung
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Heilshorn
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D032701:Biomimetics; D005109:Extracellular Matrix / Q000737:chemistry*; D006801:Humans; D049329:Nanostructures / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry*; D015202:Protein Engineering
chemical_list: D001672:Biocompatible Materials; D010446:Peptide Fragments