Elastic Properties of Single-Stranded DNA Biofilm with Strong Interactions

摘要

In label-free biodetection technologies based on microcantilevers,deflection changes induced by adsorptions of single-stranded DNA (ssDNA) molecules on Aulayer surface are greatly affected by mechanical and electrical properties of DNA biofilm.In this paper,the elastic properties of ssDNA biofilm with strong interactions are studied.First,a double-exponent interaction potential of ssDNA solution is presented referring to Parsegian's and Purohit's energy models.By Zhang's twovariable method for laminated beams,an energy model for ssDNA-microcantilever is provided.The analytical expression of deflection is obtained by the principle of minimum energy and the Taylor series method.The related parameters are obtained by curve fitting with Wu's experimental data.Second,using the thought experiment under axial compression,the stress-strain relation of ssDNA biofilm with a Gaussian distribution pattern of chain is predicted analytically.Numerical results indicate that the elastic modulus of the biofilm in linear stage is on the order of 10 MPa.