title: Gold nanoparticles: enhanced optical trapping and sensitivity coupled with significant heating.
abstract: Gold nanoparticles appear to be superior handles in optical trapping assays. We demonstrate that relatively large gold particles (R(b)=50 nm) indeed yield a sixfold enhancement in trapping efficiency and detection sensitivity as compared to similar-sized polystyrene particles. However, optical absorption by gold at the most common trapping wavelength (1064 nm) induces dramatic heating (266 degrees C/W). We determined this heating by comparing trap stiffness from three different methods in conjunction with detailed modeling. Due to this heating, gold nanoparticles are not useful for temperature-sensitive optical-trapping experiments, but may serve as local molecular heaters. Also, such particles, with their increased detection sensitivity, make excellent probes for certain zero-force biophysical assays.
authors.affiliation: JILA, University of Colorado, and National Institute of Standards and Technology, Boulder, CO 80309, USA.
authors.forename: Yeonee
authors.initials: Y
authors.lastname: Seol
authors.forename: Amanda E
authors.initials: AE
authors.lastname: Carpenter
authors.forename: Thomas T
authors.initials: TT
authors.lastname: Perkins
mesh_terms: D004735:Energy Transfer; D006046:Gold / Q000737:chemistry* / Q000528:radiation effects*; D006358:Hot Temperature; D007834:Lasers; D008846:Micromanipulation / Q000379:methods*; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013817:Thermography
chemical_list: D006046:Gold