Rotational Dynamics of Laterally Frozen Nanoparticles Specifically Attached to Biomembranes

Abstract

The strongly polarized light scattering of gold nanorods at their longitudinal plasmon frequency allows for the tracking of single gold nanorod lateral positions and orientations via optical dark-field microscopy. We monitor both lateral and rotational diffusion of polymer-coated gold nanorods attached to artificial biomembranes on solid supports. The attachment is mediated by the biotin-streptavidin receptor−ligand system, but weak interaction is also observed in the absence of streptavidin. In the latter case, we observe a two-dimensional lateral diffusion of the nanorods with a diffusion coefficient of 0.5 μm2 s−1. This lateral motion is strongly reduced with the addition of streptavidin. However, the particles are still able to rotate, and we study their rotational motion using polarization contrast microscopy. The rotational diffusion time in the range of 100 ms depends on the biotin concentration in the membrane, hence the number of anchor points, and on the temperature. Cooling the membrane beyond its gel-fluid transition point leads to a reduction of the rotational motion. The experimental results can be understood in terms of dragging forces introduced by the surface viscosity of the membrane. A quantitative analysis shows that entire patches of the membrane move with the particles.

Frozen Translational and Rotational Motion of Human Immunodeficiency Virus Transacting Activator of Transcription Peptide-Modified Nanocargo on Neutral Lipid Bilayer

“…The rotational velocity of these nanorods was found to be even slower than that of the nanorod confined on the lipid bilayer through limited number of biotin/streptavidin interactions on the side wall (∼0.025 s −1 ). 23 These interesting results imply that the hypothesis of spatial confinement effect through the formation of lipid pores on the lipid membrane is not sufficient to cause the simultaneously confined lateral and rotational motions for the nanorod.…”

Rotational dynamics of cargos at pauses during axonal transport

“…By fitting the power spectral density of the intensity traces with the Lorentzian function ( Supplementary Fig. S5) 44 , we found that the rotation characteristic time of the in-plane rotation at the pauses (8.7-14.3 ms) is longer than that of the random Brownian motion (2.1 ± 0.3 ms), indicating the rotation at these long pauses is slower than the Brownian motion.…”

The Optimal Aspect Ratio of Gold Nanorods for Plasmonic Bio-sensing

“…More recently, their plasmon resonance has been employed for more elaborate optical nanoscopicsensing schemes. The plasmon resonance of coupled particles depends on interparticle distance [1][2][3][4], and the strong plasmonic light scattering efficiency allows for the visualization of single nanorods, for example for orientation sensing [5][6][7][8]. Furthermore, the resonance position is influenced by the particle charge [9,10] and the refractive index of the particle's immediate environment [11].…”