title: Chemomechanics of surface stresses induced by DNA hybridization.
abstract: When biomolecular reactions occur on one surface of a microcantilever beam, changes in intermolecular forces create surface stresses that bend the cantilever. While this phenomenon has been exploited to create label-free biosensors and biomolecular actuators, the mechanisms through which chemical free energy is transduced to mechanical work in such hybrid systems are not fully understood. To gain insight into these mechanisms, we use DNA hybridization as a model reaction system. We first show that the surface grafting density of single-stranded probe DNA (sspDNA) on a surface is strongly correlated to its radius of gyration in solution, which in turn depends on its persistence length and the DNA chain length. Since the persistence length depends on ionic strength, the grafting density of sspDNA can be controlled by changing a solution's ionic strength. The surface stresses produced by the reaction of complementary single-stranded target DNA (sstDNA) to sspDNA depend on the length of DNA, the grafting density, and the hybridization efficiency. We, however, observe a remarkable trend: regardless of the length and grafting density of sspDNA, the surface stress follows an exponential scaling relation with the density of hybridized sspDNA.
authors.affiliation: Department of Mechanical Engineering, University of California, Berkeley, California 94720, USA.
authors.forename: Jeanne C
authors.initials: JC
authors.lastname: Stachowiak
authors.forename: Min
authors.initials: M
authors.lastname: Yue
authors.forename: Kenneth
authors.initials: K
authors.lastname: Castelino
authors.forename: Arup
authors.initials: A
authors.lastname: Chakraborty
authors.forename: Arun
authors.initials: A
authors.lastname: Majumdar
mesh_terms: D001483:Base Sequence; D001672:Biocompatible Materials / Q000737:chemistry; D001696:Biomechanical Phenomena; D015374:Biosensing Techniques; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004247:DNA / Q000737:chemistry*; D008422:Materials Testing; D044085:Microfluidics; D009693:Nucleic Acid Hybridization; D020411:Oligonucleotide Array Sequence Analysis; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D001672:Biocompatible Materials; D004247:DNA