Mechanical properties of DNA biofilms adsorbed on microcantilevers in label-free biodetections.
Biomolecule adsorption is a fundamental process in the design of biosensors. Mechanical/electrical/thermal properties of biofilms have great influences on biodetection signals. The double-stranded DNA (dsDNA) biofilm adhered on microcantilever is treated as a bending beam with a macroscopic elastic modulus in the viewpoint of continuum mechanics. Accounting for hydration force, electrostatic repulsion and conformational entropy, moment-angle diagrams of dsDNA biofilm in pure bending state are depicted with the help of the energy conservation law and a mesoscopic liquid crystal theory presented by Strey et al. An analytical model is provided to predict macroscopic elastic modulus of dsDNA biofilm as a function of nanoscopic properties of dsDNA, packing density, buffer salt concentration and etc. The parameters for microcantilever-DNA system are obtained by curve fitting with Stachowiak's experimental data based on a modified Stoney's formula. Elastic modulus grows exponentially with the enhancement of packaging density, but diminishes with the increase of buffer salt concentration, and its order is about 1 approximately 10 MPa. Conformational entropy is one of predominant factors considered in near-surface system whether in high or low salt consternation.
Zhang
Neng-Hui
NH
Department of Mechanics, College of Sciences, Shanghai University, Shanghai 200444, China. nhzhang@shu.edu.cn
Chen
Jian-Zhong
JZ
Li
Jing-Jing
JJ
Tan
Zou-Qing
ZQ
D000327:Adsorption; D015374:Biosensing Techniques / Q000379:methods*; D004247:DNA / Q000737:chemistry*; D055119:Elastic Modulus; D055595:Mechanical Phenomena; D013816:Thermodynamics
D004247:DNA