Direct Measurements of Heating by Electromagnetically Trapped Gold Nanoparticles on Supported Lipid Bilayers

Abstract

Absorption of electromagnetic irradiation results in significant heating of metallic nanoparticles, an effect which can be advantageously used in biomedical contexts. Also, metallic nanoparticles are presently finding widespread use as handles, contacts, or markers in nanometer scale systems, and for these purposes it is essential that the temperature increase associated with electromagnetic irradiation is not harmful to the environment. Regardless of whether the heating of metallic nanoparticles is desired or not, it is crucial for nanobio assays to know the exact temperature increase associated with electromagnetic irradiation of metallic nanoparticles. We performed direct measurements of the temperature surrounding single gold nanoparticles optically trapped on a lipid bilayer, a biologically relevant matrix. The lipid bilayer had incorporated fluorescent molecules which have a preference for either fluid or gel phases. The heating associated with electromagnetic radiation was measured by visualizing the melted footprint around the irradiated particle. The effect was measured for individual gold nanoparticles of a variety of sizes and for a variety of laser powers. The temperatures were highly dependent on particle size and laser power, with surface temperature increments ranging from a few to hundreds of degrees Celsius. Our results show that by a careful choice of gold nanoparticle size and strength of irradiating electromagnetic field, one can control the exact particle temperature. The method is easily applicable to any type of nanoparticle for which the photothermal effect is sought to be quantified.

Guidable Thermophoretic Janus Micromotors Containing Gold Nanocolorifiers for Infrared Laser Assisted Tissue Welding

“…It is worth to point out that the observed laser based heating presented here is in line with the absorption and heating rates of nanoparticles, whose heating rate was observed not by whole particle motion, but rotational changes, as well as with simulated or lipid bilayer disordering studies 23, 24, 25, 26, 27. Also temperature measurements of Janus particle based cancer treatment agents resulted in similar values like the ones presented here 21.…”

Electromagnetic absorption mechanisms in metal nanospheres: Bulk and surface effects in radiofrequency-terahertz heating of nanoparticles

“…Individual nanoparticles must be subject to an intense electric field to heat substantially; e.g., in Ref. 2 individual gold nanoparticles heated by several hundred degrees when the incident laser intensity was I $ 1 GW/m 2 , yet individual nanoparticles are projected to heat far less than a degree for intensities on the order of 10 4 W/m 2 (Ref.…”

Optical trapping and manipulation of plasmonic nanoparticles: fundamentals, applications, and perspectives

“…17,68,69 Due to their small volume bubble formation is suppressed and local temperatures signicantly exceeding the boiling point of the surrounding medium can be achieved. 70,71 Even under off-resonant excitation conditions (with respect to the LSPR), as present in an optical trap, signicant temperature increases can be observed. Optical trapping offers possibilities to quantify the induced temperature proles and to study their effect on chemical and biochemical processes.…”