Web Release Date: February 15,
Mechanically Tunable Thin Films of Photosensitive Artificial Proteins: Preparation and Characterization by Nanoindentation
and
Division of Chemistry and Chemical Engineering, Joseph J. Jacobs Institute for Molecular Engineering for Medicine, and Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125
Received July 31, 2007
Revised Manuscript Received December 12, 2007
Abstract:
Thin films of controlled elastic modulus were made by photo-cross-linking artificial extracellular matrix (aECM) proteins containing the photosensitive amino acid p-azidophenylalanine (pN3Phe). The elastic moduli of the films were calculated from nanoindentation data collected by atomic force microscopy (AFM) using a thin-film Hertz model. The modulus was shown to be tunable in the range 0.3-1.0 MPa either by controlling the irradiation time or by varying the level of pN3Phe in the protein. Tensile measurements on bulk films of the same proteins and finite-element simulation of the indentation process agreed with the thin-film modulus measurements from AFM. Substrates characterized by spatial variation in elastic modulus were created by local control of the irradiation time.
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