Electrostatic Nanomechanics of Cantilever Biosensors


Article Preview

Interest in microcantilever based biosensors in the biomedical field has largely increased during the last years. Potentially, this kind of sensor can provide a considerable contribution to complex disease diagnosis, which requires the detection of biological molecules. Microcantilever biosensors allow the detection of complementary DNA fragment hybridization or specific antibody-antigen binding; it is known that adsorption of specific biological molecules upon the microcantilever surface induces cantilever deflection due to the interaction of the molecules with the surface. To date, the phenomena which determine the deflection mechanism are not completely known. The present work investigates the electrostatic field within the molecules and the forces consequently acting on the molecules and on the cantilever in order to provide a description of the deflection mechanism. The electrostatic potential of arrays of double strand DNA molecules immersed in an ionic solution was modelled by means of cylinders negatively charged at the surface and a FE (Finite Element) continuum electrostatics analysis was implemented in order to numerically solve the second order non-linear Poisson-Boltzmann equation. Then, a FE structural analysis of the cantilever was performed coupled with the continuum electrostatics analysis. In this way, the effects of the molecules’ electrostatic interactions on the cantilever deflection were taken into account. The model was run to describe the microcantilever deflection due to the electrostatic field under different design and operating conditions, and it was also set to compare hexagonal and square disposition of double strand DNA molecules.



Materials Science Forum (Volumes 539-543)

Main Theme:

Edited by:

T. Chandra, K. Tsuzaki, M. Militzer , C. Ravindran




M. Merlo et al., "Electrostatic Nanomechanics of Cantilever Biosensors", Materials Science Forum, Vols. 539-543, pp. 595-601, 2007

Online since:

March 2007




[1] J. Fritz, M.K. Baller, H.P. Lang, H. Rothuizen, P. Vettiger, E. Meyer, H.J. Güntherodt, C. Gerber and J.K. Gimzewski, Translating biomolecular recognition into nanomechanics, Science 228 (2000), 316-318.

[2] T. Thundat, P.I. Oden and R.J. Warmack, Microcantilever sensors, Microscale Thermophys. Eng. 1 (1997), 185-199.

[3] G. Wu, H. Ji, K. Hansen, T. Thundat, R. Datar, R. Cote, M.F. Hagan, A.K. Chakraborty and A. Majumdar, Origin of nanomechanical cantilever motion generated from biomolecular interactions, Proc. Natl. Acad. Sci. USA 98 (2001), 1560-1564.

DOI: https://doi.org/10.1073/pnas.98.4.1560

[4] K.M. Hansen, H.F. Ji, G. Wu, R. Datar, R. Cote, A. Majumdar, and T. Thundat, Cantilever-based optical deflection assay for discrimination of DNA single-nucleotide mismatches, Anal. Chem. 73 (2001), 1567-1571.

DOI: https://doi.org/10.1021/ac0012748

[5] G. Wu, R. Datar, K. Hansen, T. Thundat, R. Cote, and A. Majumdar, Bioassay of prostatespecific antigen (PSA) using microcantilevers, Nat. Biotechnol. 19 (2001), 856-860.

DOI: https://doi.org/10.1038/nbt0901-856

[6] A. Majumdar, Bioassays based on molecular nanomechanics, Dis. Markers 18 (2002), 167-174.

[7] M.F. Hagan, A. Majumdar and A.K. Chakraborty, Nanomechanical forces generated by surface grafted DNA, J. Phys. Chem. B 106 (2002), 10163-10173.

DOI: https://doi.org/10.1021/jp020972o

[8] M. Yue, H. Lin, D.E. Dedrick, S. Satyanarayana, A. Majumdar, A.S. Bedekar, J.W. Jenkins and S. Sundaram, A 2-D microcantilever array for multiplexed biomolecular analysis, J. Microelectromechanical Systems 13 (2004), 290-299.

DOI: https://doi.org/10.1109/jmems.2003.823216

[9] R. Raiteri, M. Grattarola, H.J. Butt and P. Skladal, Micromechanical cantilever-based biosensors, Sens. Actuators B 79 (2001), 115-126.

DOI: https://doi.org/10.1016/s0925-4005(01)00856-5

[10] D. Chapot, L. Bocquet and E. Trizac, Electrostatic potential around finite rodlike macromolecules: non linear Poisson-Boltzmann theory, J. Colloid Interface Sci. 285 (2005), 609-618.

DOI: https://doi.org/10.1016/j.jcis.2004.11.059

[11] D. Harries, Solving the Poisson-Boltzmann equation for two parallel cylinders, Langmuir 14 (1998), 3149-3152.

DOI: https://doi.org/10.1021/la971314b

[12] M. K. Gilson, M. E. Davis, B. A. Luty and J. A. McCammon, Computation of electrostatic forces on solvated molecules using the Poisson-Boltzmann equation, J. Phys. Chem. 97 (1993), 3591-3600.

DOI: https://doi.org/10.1021/j100116a025

[13] M. Ospeck and S. Fraden, Solving the Poisson-Boltzmann equation to obtain interaction energies between confined like-charged cylinders, J. Chem. Phys. 20 (1998), 9166-9171.

DOI: https://doi.org/10.1063/1.477469

[14] S. L. Brenner and A. Parsegian, A physical method for deriving the electrostatic interaction between rod-like polyions at all mutual angles, Biophys. J. 14 (1974), 327-334.

DOI: https://doi.org/10.1016/s0006-3495(74)85919-9

[15] F. Fogolari, A. Brigo and H. Molinari, The Poisson-Boltzmann equation for biomolecular electrostatics: a tool for structural biology, J. Mol. Recognit. 15 (2002), 377-392. January 2007: Revised Version.

DOI: https://doi.org/10.1002/jmr.577