Professor Lene Oddershede, Niels Bohr Institute, Biocomplexity, Copenhagen University

Optical Manipulation and Bio-applications of Plasmonic Nanoparticles

A tightly focused laser beam can trap and manipulate individual metallic nanoparticles both in liquid [1] and in air [2]. Not only the position, but also the orientation of a single nanoparticle can be controlled and a precise optical control of metallic nanoparticles has huge potential, e.g., for aerotaxy or nano-architectural purposes. Due to their plasmonic properties, metallic nanoparticles will absorb part of the incident light and the energy will be released as heat into their local surroundings. The heating associated with resonant irradiation of metallic nanoparticles can be extreme. Moreover, this heating of an irradiated nanoparticle cannot be theoretically predicted, as the precise focal intensity distribution on the nanoscale is unknown and typically highly aberrated [3]. We developed a novel membrane-based assay to directly quantify the temperature profile of an individual irradiated metallic nanoparticle and show how the temperature depends on laser power and particle size, shape, orientation and composition [4,5]. Laser induced heating of metallic nanoparticles can be advantageously used in a controlled manner, for instance to fuse membranes and cargos of two selected giant unilamellar vesicles [6]. Another promising application of these hot metallic nanoparticles is within cancer therapy, where novel results show that laser irradiated metallic nanoparticles can be used to mediate targeted drug delivery and for photothermal tumor treatment. 

[1] Hansen et al., Expanding the optical trapping range of gold nanoparticles, Nano Letters, vol. 5 p.1937-1942 (2005).
[2] Jauffred, Taheri, Schmitt, Linke, Oddershede. Optical Trapping of Gold Nanoparticles in Air. Nano Letters, vol. 15 p. 4713-4719 (2015).
[3] Kyrsting et al., Mapping 3D focal intensity exposes the stable trapping positions of single nanoparticles. Nano Letters vol.13 p.31-35 (2013).
[4] Bendix et al., Direct measurements of heating by electromagnetically trapped gold nanoparticles on supported lipid bilayers, ACS Nano, vol. 4 p.2256-2262 (2010).
[5] Ma et al., Heat generation by irradiated complex composite nanostructures. Nano Letters, vol. 14 p.612-619 (2014).
[6] A. Rørvig-Lund, Bahadori, Semsey, Bendix, Oddershede. Vesicle fusion triggered by optically heated gold nanoparticles, Nano Letters, vol. 15 p. 4183-4188 (2015).