Thermoplasmonic Effects of Gold Nanorods

Gold nanoparticles have been used in recent decades in many biomedical applications including photothermal therapies, sensing, and enhanced spectroscopies due to their unique plasmonic properties. These properties which can include enhanced electric fields and a localized photothermal heating effect, result from their localized surface plasmon resonance (LSPR). The LSPR itself is dependent on many factors including properties of the particle such as shape, size, and composition but also on the dielectric properties of the surrounding medium and the presence of neighboring particles (plasmonic interactions). In addition to utilizing directly the photothermal effect, there has been interest in the effect of that plasmonic heating on bound biomolecules that can be used for in vivo studies. With the potential development of new applications using these hybrid plasmonic systems there now arises the need for more basic knowledge on the relationship of the plasmonic heating of nanoparticles to coupled biomolecules. In this work we created a computational model of gold nanorods that can be used to predict the plasmonic and photothermal effects of various nanoparticles and nanoparticle-biomolecule conjugates including temperature profiles and rates of temperature increase. These models were compared to a photothermal heat study conducted using synthesized gold nanorods coupled to bovine and human serum albumin (BSA and HSA). Future work in this study will include examining the heating effect of the gold nanorods on the coupled proteins experimentally using analytical techniques such as Raman spectroscopy.