ABSTRACT
Objective To investigate the dependency of thermal expansion coefficient of DNA adsorption film on environmental conditions. Methods By treating DNA adsorption film as a macroscopic continuum film with prestrain, an equivalent composite beam model of DNA film-substrate was established to calculate the deflection of DNA-microcantilever beam under temperature loading. By adopting Parsegian’s empirical potential which described the mesoscopic free energy of DNA adsorption film, the DNA liquid crystal-substrate multi-scale deflection model, the thought experiment method and the equivalent deformation method were combined to establish the trans-scale relationship between the microstructure of DNA adsorption film and its macro-scale mechanical properties. The thermal expansion coefficient of DNA adsorption film was predicted. ResultsGiven the ionic strength, the thermal expansion coefficient of double-stranded DNA adsorption film ranged from 0.3×10-4/K to 8.05×10-4/K, and that of single-stranded DNA adsorption film ranged from 1.28×10-4/K to 9.33×10-4/K. Conclusions As a leading role in the competition of micro-interactions, the change of configurational entropy determines the dependency of thermal expansion coefficient of DNA adsorption film on environmental conditions; the thermal expansion coefficient of DNA adsorption film decreases with the increase of temperature or ion concentration or DNA packing density. These results are useful for gene detection and its regulation, and provide reference for the evaluation of tissue organ performance in tissue engineering.
ABSTRACT
Objective To investigate the influence of the microscale attractive interaction on the elastic properties of DNA film in multivalent ion solutions. Methods Kornyshev's electrostatic zipper model was employed to describe the interaction energy between the DNA strands. The thought experiment method and macroscopic continuum bar model were combined to predict the stress-strain relationship, prestress, and elastic modulus of the DNA biofilm.Results Given the packing conditions, the DNA film exhibited a tensile prestress and negative elastic modulus. The prestress of the DNA biofilm ranged from -1.52 MPa to 1.17 MPa, and its elastic modulus ranged from -4.2 MPa to 64 MPa. Conclusions In contrast with monovalent solutions, the microscopic attractive interactions in multivalent solutions caused the elastic properties of the DNA film to exhibit a non-monotonous relationship with the variation in the packing density and salt concentration. The tensile elastic properties were significantly different from the compressive ones, and the tensile/compressive prestress as well as the positive/negative elastic modulus transformed each other. These results can contribute to understanding the mechanism of viral replication and provide references for gene detection and gene therapy.