Synthesis and Characterization of Novel Nanothermometers

Abstract

Nanothermometers enable the measurement of local temperatures at nanoscale dimensions (1-100 nm), which can provide insight into many biological and industrial applications. Previously synthesized nanothermometers are similar to molecular beacons, consisting of fluorescently labeled stem-loop DNA strands linked to gold nanoparticles (AuNPs) via a thiol-gold link- age. The principle behind their operation is that the fluorophore is quenched by the nanoparticle due to the self-binding of the stem-loop DNA at low temperatures. As the nanothermometers are heated, the stem-loop unfolds at its characteristic melting point, and as a result, the fluorophore is no longer in the quenching region of the nanoparticle and a dramatic rise in fluores- cence will occur. The temperature response of the nanothermometer can be selected by optimizing the sequence of the DNA strand. Typically, the AuNPs only serve to quench the fluorophores in these types of nanothermometers. However, by anchoring stem-loop DNA to functional nanoparticles, a new type of system is created, one which can provide tailored functionality and also real-time, local temperature information. For example, AuNPs can be used for their catalytic, plasmonic and visible light properties, Fe2O3 nanoparticles can be used for their magnetic and photocatalytic properties, and Pd can be used for catalysis or hydrogen storage. In an effort to create nanothermometers that also possess these multifunctional properties, we have successfully synthesized a variety of nanothermometers supported by a variety of nanoparticles, including Au, Au-Fe2O3, Pd, Pd-Fe2O3, and Au-Pd-Fe2O3 nanoparticles. The obtained nanothermometers are currently being characterized by fluorescence spectroscopy, scanning electron microscopy, UV-Vis spectroscopy, and phase analysis light scattering (PALS). Funding Source: Department of Energy