MicroCantilever (MC) based nanomechanical sensor for detection of molecular interactions

dc.contributor.advisor Pranav Shrotriya
dc.contributor.author Kang, Kyungho
dc.contributor.department Mechanical Engineering
dc.date 2018-08-11T19:12:19.000
dc.date.accessioned 2020-06-30T02:40:40Z
dc.date.available 2020-06-30T02:40:40Z
dc.date.copyright Sat Jan 01 00:00:00 UTC 2011
dc.date.embargo 2013-06-05
dc.date.issued 2011-01-01
dc.description.abstract <p>Specific aims of this study are to investigate the mechanism governing surface stress generation associated with chemical or molecular binding on functionalized microcantilevers. Formation of affinity complexes on cantilever surfaces leads to charge redistribution, configurational change and steric hindrance between neighboring molecules resulting in surface stress change and measureable cantilever deformation. A novel interferometry technique employing two adjacent micromachined cantilevers (a sensing/reference pair) was utilized to measure the cantilever deformation. The sensing principle is that binding/reaction of specific chemical or biological species on the sensing cantilever transduces to mechanical deformation. The differential bending of the sensing cantilever respect to the reference cantilever ensures that measured response is insensitive to environmental disturbances. As a proof of principle for the measurement technique, surface stress changes associated with: self-assembly of alkanethiol, hybridization of ssDNA, and the formation of cocaine-aptamer complexes were measured. Dissociation constant (Kd) for each molecular reaction was utilized to estimate the surface coverage of affinity complexes. In the cases of DNA hybridization and cocaine-aptamer binding, measured surface stress was found to be dependent on the surface coverage of the affinity complexes. In order to achieve a better sensitivity for DNA hybridization, immobilization of receptor molecules was modified to enhance the deformation of underlying surface. Single-stranded DNA (ssDNA) strands with thiol-modification on both 3' and 5' ends were immobilized on the gold surface such that both ends are attached to the gold surface. Immobilization condition was controlled to obtain similar receptor density as single-thiolated DNA strands. Hybridization of double-thiolated DNA strands leads to an almost two orders of magnitude increase in cantilever deformation. In both DNA hybridization and the conventional mode for cocaine detection, the lowest detectable concentration was determined by binding activity between the ligand and receptor molecules. In order to overcome this limitation for cocaine detection, a novel competition sensing mode that relies on rate of aptamers unbinding from the cantilever due to either diffusion or reaction with cocaine as target ligands in solution was investigated. The rate of unbinding is found to be dependent on the concentration of cocaine molecules. A model based on diffusion-reaction equation was developed to explain the experimental observation. Experimental results indicate that the competition mode reduces the lowest detectable threshold to 200 nM which is comparable to that achieved analytical techniques such as mass spectrometry.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/etd/12148/
dc.identifier.articleid 3145
dc.identifier.contextkey 2808343
dc.identifier.doi https://doi.org/10.31274/etd-180810-2204
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath etd/12148
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/26342
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/etd/12148/Kang_iastate_0097E_11936.pdf|||Fri Jan 14 19:13:59 UTC 2022
dc.subject.disciplines Mechanical Engineering
dc.title MicroCantilever (MC) based nanomechanical sensor for detection of molecular interactions
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
relation.isOrgUnitOfPublication 6d38ab0f-8cc2-4ad3-90b1-67a60c5a6f59
thesis.degree.level dissertation
thesis.degree.name Doctor of Philosophy
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