Multilayered Dual Functional SiO2@Au@SiO2@QD Nanoparticles for Simultaneous Intracellular Heating and Temperature Measurement

This paper discusses synthesis and application of dual functional SiO₂@Au@SiO₂@QD composite nanoparticles for integrated intracellular heating with temperature motoring. The particles are of multilayered concentric structure, consisting of Au nanoshells covered with quantum dots, with the former for infrared heating through localized surface plasma resonance while the later for temperature monitoring. The key to integrate plasmonic-heating/thermal-monitoring on a single composite nanoparticle is to ensure that the quantum dots be separated at a certain distance away from the Au shell surface in order to ensure a detectable quantum yield. Direct attachment of the quantum dots onto the Au shell would render the quantum dots practically functionless for temperature monitoring. To integrate quantum dots into Au nanoshells, a quantum quenching barrier of SiO₂ was created by modifying a Stober-like process. Materials, optical and thermal characterization was made of these composite nanoparticles. Cellular uptake of the nanoparticles was discussed. Experiments were performed on simultaneous in vitro heating and temperature monitoring in a cell internalized with the dual-functional SiO₂@Au@SiO₂@QD composite nanoparticles.