Mechanical properties of double-stranded DNA biolayers immobilized on microcantilever under axial compression |
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Authors: | Neng-Hui Zhang Jian-Zhong Chen |
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Institution: | 1. Max Planck Institute for Intelligent Systems (formerly Max Planck Institute for Metals Research), Heisenbergstr. 3, 70569 Stuttgart, Germany;2. Robert Bosch GmbH, Automotive Electronics/Engineering Assembly and Interconnect Technology (AE/EAI2), Robert-Bosch-Str. 2, 71701 Schwieberdingen, Germany;3. Institute for Materials Science, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany |
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Abstract: | In label-free biodetections based on microcantilever technology, double-stranded DNA (dsDNA) structures form through the linkage between probe single-stranded DNA (ssDNA) molecules immobilized on solid substrates and target ssDNA molecules in solutions. Mechanical/electrical properties of these biolayers are important factors for nanomechanical deflections of microcantilevers. In this paper, the biolayer immobilized on microcantilever is treated as a bar with a macroscopic elastic modulus on the basis of continuum mechanics viewpoints. In consideration of hydration force, screened electrostatic repulsion and conformational fluctuation in biolayers, load-deformation curves of dsDNA biolayers under axial compression are depicted with the help of the energy conservation law and a mesoscopic free energy presented by Strey et al. (1997, 1999) Strey, H.H., Parsegian, V.A., Podgornik, R., 1997. Equation of state for DNA liquid crystals: fluctuation enhanced electrostatic double layer repulsion. Physical Review Letters 78, 895–898; Strey, H.H., Parsegian, V.A., Podgornik, R., 1999. Equation of state for polymer liquid crystals: theory and experiment. Physical Review E 59, 999–1008] from a liquid crystal theory. And the analytical relation between macroscopic Young's modulus of biolayers and nanoscopic geometrical properties of dsDNA, packing density, buffer salt solution concentration, etc. is also formulated. |
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