AVS 50th International Symposium
    Biomaterial Interfaces Thursday Sessions
       Session BI-ThM

Paper BI-ThM10
Material and Surface Characterization of Electrodeposited Polysaccharide Chitosan Film as a Platform for Biomolecular Reactions in BioMEMS Systems

Thursday, November 6, 2003, 11:20 am, Room 318/319

Session: Biosensors
Presenter: C. Pederzolli, ITC-IRST, Italy
Authors: C. Pederzolli, ITC-IRST, Italy
L. Lunelli, ITC-IRST, Italy
G. Speranza, ITC-IRST, Italy
R. Canteri, ITC-IRST, Italy
M. Anderle, ITC-IRST, Italy
J.J. Park, University of Maryland
L.-Q. Wu, University of Maryland
H. Yi, University of Maryland
R. Ghodssi, University of Maryland
W.E. Bentley, University of Maryland
G.F. Payne, University of Maryland
G.W. Rubloff, University of Maryland
Correspondent: Click to Email
The polysaccharide chitosan provides a high density of amine sites for biomolecular adsorption and reaction. Exploiting the fact that under mildly acidic conditions (pKa=6.3) chitosan is water soluble with the amine groups positively charged, we have electrodeposited chitosan onto negative electrodes and demonstrated schemes for attachment of fluorophores, proteins and nucleic acids. The chitosan films can be deposited as relatively compact films or hydrogels, depending on process conditions. We have studied film properties by changing to high pH after deposition, rinsing, and drying. Measurements indicate a complex structure with density substantially lower than expected for a closed packed film, consistent with AFM images which reveal a morphology with substantial (50-150 nm) roughness. One may anticipate deprotonation and local enhancement of the pH at the surface during deposition, which could be accompanied by H@sub2@ evolution; localized features observed in AFM images could be consistent with H@sub2@ bubble formation during electrodeposition. Estimates of amine site density made from these observations are in agreement with fluorescence intensity measurements that directly reveal densities in the range 10@super14@-10@super15@ sites/cm@super2@. XPS and ToF-SIMS reveal chemical components of glucosamine (-CH@sub2@-NH@sub2@) and also of N-acetylglucosamine (-NH-(C=O)-) the monomeric residues of chitosan. The extent of cell adhesion on these chitosan films was analyzed using fibroblast-like cells (NIH-3T3, HGF-1), and results indicate that cell adhesion and growth are dependent on deposition parameters and film thickness. These observations of the materials and surface properties are important for our use of electrodeposited chitosan as a platform for biomolecular reactions in bioMEMS systems.