Single DNA molecule detection in an optical trap using surface-enhanced Raman scattering

Raman spectra from single DNA molecules in their natural aqueous environment are presented. A DNA molecule that is anchored between two optically trapped dielectric beads is suspended in a solution with nanosized silver colloid particles. The nonspecific binding of the metal to the DNA enhances the Raman scattering that is excited by a near-infrared beam. A Raman spectrum is first recorded followed by a force-extension curve that verifies the presence of a single DNA molecule. (C) 2010 American Institute of Physics. [doi:10.1063/1.3431628]