analyzing-movement-nauplius-artemia-salina-optical-tracking-plasmonic

Analyzing the Movement of the Nauplius '<em>Artemia salina</em>' by Optical Tracking of Plasmonic Nanoparticles

We demonstrate how optical tweezers may provide a sensitive tool to analyze the fluidic vibrations generated by the movement of small aquatic organisms. A ...

Ludwig-Maximilians-Universität

We propose and demonstrate a new method of an all-optical, contactless, one-step injection of single gold nanoparticles through phospholipid membranes. The method is based on the combination of strong optical forces acting on and simultaneous optical heating of a gold nanoparticle exposed to laser light tuned to the plasmon resonance of the nanoparticle. A focused laser beam captures single nanoparticles from the colloidal suspension, guides them toward a phospholipid vesicle and propels them through the gel-phase membrane, resulting in the nanoparticle internalization into the vesicle. Efficient resonant optical heating of the gold nanoparticle causes a pore to form in the gel-phase membrane, a few-hundred nanometers in size, which remains open for several minutes.

Single-step injection of gold nanoparticles through phospholipid membranes.

We have coated gold nanorods (NRs) with thermoresponsive microgel shells based on poly(N-isopropylacrylamide) (pNIPAM). We demonstrate by simultaneous laser-heating and optical extinction measurements that the Au NR cores can be simultaneously used as fast optothermal manipulators (switchers) and sensitive optical reporters of the microgel state in a fully externally controlled and reversible manner. We support our results with optical modeling based on the boundary element method and 3D numerical analysis on the temperature distribution. Briefly, we show that due to the sharp increase in refractive index resulting from the optothermally triggered microgel collapse, the longitudinal plasmon band of the coated Au NRs is significantly red-shifted. The optothermal control over the pNIPAM shell, and thereby over the optical response of the nanocomposite, is fully reversible and can be simply controlled by switching on and off a NIR heating laser. In contrast to bulk solution heating, we demonstrate that light-triggering does not compromise colloidal stability, which is of primary importance for the ultimate utilization of these types of nanocomposites as remotely controlled optomechanical actuators, for applications spanning from drug delivery to photonic crystals and nanoscale motion.

Triggering the volume phase transition of core-shell Au nanorod-microgel nanocomposites with light.

We propose and demonstrate a hybrid lithographic technique capable of nanopatterning surfaces by optothermal decomposition of a polymeric film induced by a single metal nanoparticle. A tightly focused laser beam exerting a strong optical force onto the nanoparticle is used to move it inside the polymer film. Due to efficient plasmonic absorption of the laser light, the nanoparticle is heated up to temperatures of several hundred degrees, causing melting or even thermal decomposition of the polymer film. By this method, grooves less than 100 nm wide and tens of micrometers long can be directly milled in a polymer layer.

Subdiffraction-limited milling by an optically driven single gold nanoparticle.

The genus Lens comprises a range of closely related species within the galegoid clade of the Papilionoideae family. The clade includes other important crops (e.g. chickpea and pea) as well as a sequenced model legume (Medicago truncatula). Lentil is a global food crop increasing in importance in the Indian sub-continent and elsewhere due to its nutritional value and quick cooking time. Despite this importance there has been a dearth of genetic and genomic resources for the crop and this has limited the application of marker-assisted selection strategies in breeding.

Ancient orphan crop joins modern era: gene-based SNP discovery and mapping in lentil.

We report on the deposition of individual gold nanorods from an optical trap using two different laser wavelengths. Laser light, not being resonant to the plasmon resonances of the nanorods, is used for stable trapping and in situ alignment of individual nanorods. Laser light, being resonant to the transversal mode of the nanorods, is used for depositing nanorods at desired locations. The power and polarization dependence of the process is investigated and discussed in terms of force balances between gradient and scattering forces, plasmonic heating, and rotational diffusion of the nanorods. This two-color approach enables faster printing than its one-color equivalent and provides control over the angular orientation (±16°) and location of the deposited nanorods at the single-nanorod level.

Two-color laser printing of individual gold nanorods.

Noble-metal particles feature intriguing optical properties, which can be utilized to manipulate them by means of light. Light absorbed by gold nanoparticles, for example, is very efficiently converted into heat, and single particles can thus be used as a fine tool to apply heat to a nanoscopic area. At the same time, gold nanoparticles are subject to optical forces when they are irradiated with a focused laser beam, which renders it possible to print, manipulate, and optically trap them in two and three dimensions. Here, we demonstrate how these properties can be used to control the polymerization reaction and thermal curing of polydimethylsiloxane (PDMS) at the nanoscale and how these findings can be applied to synthesize polymer nanostructures such as particles and nanowires with subdiffraction limited resolution.

Article	Year
Single-step injection of gold nanoparticles through phospholipid membranes. ACS nano\| PubMed ID: 21488672	2011
Triggering the volume phase transition of core-shell Au nanorod-microgel nanocomposites with light. Nanotechnology\| PubMed ID: 21543835	2011
Subdiffraction-limited milling by an optically driven single gold nanoparticle. ACS nano\| PubMed ID: 21812459	2011
Ancient orphan crop joins modern era: gene-based SNP discovery and mapping in lentil. BMC genomics\| PubMed ID: 23506258	2013
Two-color laser printing of individual gold nanorods. Nano letters\| PubMed ID: 23927535	2013
Nanolithography by plasmonic heating and optical manipulation of gold nanoparticles. ACS nano\| PubMed ID: 23941522	2013

Michael Fedoruk

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