a
Department of Materials Science and Engineering, Delaware Biotechnology Institute, University of Delaware, 201 DuPont Hall, Newark, USA
E-mail: xjia@udel.edu
;
Fax: +1 302-831-4545
;
Tel: +1 302-831-6553
b
DuPont Nanotechnologies, CR&D, DuPont Co., Wilmington, USA
c
Biomedical Engineering Program, University of Delaware, Newark, USA