Permanent Fixing or Reversible Trapping and Release of DNA Micropatterns on a Gold Nanostructure Using Continuous-Wave or Femtosecond-Pulsed Near-Infrared Laser Light

Abstract

The use of localized surface plasmons (LSPs) for highly sensitive biosensors has already been investigated, and they are currently being applied for the optical manipulation of small nanoparticles. The objective of this work was the optical trapping of λ-DNA on a metallic nanostructure with femtosecond-pulsed (fs) laser irradiation. Continuous-wave laser irradiation, which is generally used for plasmon excitation, not only increased the electromagnetic field intensity but also generated heat around the nanostructure, causing the DNA to become permanently fixed on the plasmonic substrate. Using fs laser irradiation, on the other hand, the reversible trapping and release of the DNA was achieved by switching the fs laser irradiation on and off. This trap-and-release behavior was clearly observed using a fluorescence microscope. This technique can also be used to manipulate other biomolecules such as nucleic acids, proteins, and polysaccharides and will prove to be a useful tool in the fabrication of biosensors.

Insight into plasmonic hot-electron transfer and plasmon molecular drive: new dimensions in energy conversion and nanofabrication

“…These ring patterns could be controlled by using the trapping laser power and the numerical aperture of the objective. Although the observation of a ring pattern was very similar to that by the Tsuboi group, 69 a contrasting Plasmonic hot-electron transfer and nanofabrication A Furube and S Hashimoto mechanism that is entirely photothermal with no optical trapping force was postulated because of the absence of plasmonic substrates. However, we note that the tight focus with an NA 1.2 objective may sometimes generate optical gradients and scattering forces sufficient to form patterned aggregates on the substrates depending on the laser power.…”

“…A DNA ring of approximately the size of a focused laser spot was found to form permanently on a focused CWlaser (λ = 808 nm) illumination assisted by the Au twin-pyramid structure at an intensity of 5 × 10 3 W cm − 2 . 69 Interestingly, for femtosecond laser irradiation (λ = 770 nm, 80 MHz, 120 fs), only reversible trapping and release was observed. The mechanism behind this structural formation was not fully uncovered but the balance of an attractive gradient force and repulsive thermophoretic force because of accumulated heat may contribute to the structure.…”

Understanding and controlling plasmon-induced convection

“…Indeed, light-absorbing nanotextured surfaces such as those utilizing metal pads, dipole antennas and bowtie nanoantennas have recently been shown to be very effective for optical manipulation 9,13,15 . These plasmonic 'nanotweezers' have multidisciplinary applications spanning biological species manipulation 16 , colloidal physics and optical matter formation 9,17 , DNA aggregation 15 , lab-on-a-chip particle manipulation 6 and fundamental optical physics 18 . In all cases, thermal convection generated as a result of the frequencydependent absorption of optical energy by the metallic nanostructures plays an important role in the particle trapping behaviour observed 9,12 .…”

Characterization of the near-field and convectional transport behavior of micro and nanoparticles in nanoscale plasmonic optical lattices

“…6 Plasmonic-based, near-field optical manipulation has been developed to overcome these diffraction-imposed limitations, and has been successfully applied to trap dielectric and metallic nanoparticles, and bacteria. [7][8][9][10] In liquid environments, these efforts have culminated in the recent demonstration of the tweezing of a single protein molecule and measurement of mechanical vibration to reveal its identity with the extraordinary acoustic Raman technique. [11][12][13][14][15] Technical advances in conventional optical trapping techniques have enabled the creation of microscale and nanoscale one-, two-, and three-dimensional periodic potentials (or optical lattices).…”