a
Single Molecule Study Laboratory, College of Engineering and Nanoscale Science and Engineering Center, University of Georgia, Athens, USA
E-mail: bxu@engr.uga.edu
;
Fax: +1-706-542-3804
;
Tel: +1-706-542-0502
b
Complex Carbohydrate Research Center and Department of Biochemistry and Molecular Biology, University of Georgia, Athens, USA