Highly efficient ratiometric nanothermometers based on colloidal carbon quantum dots
Yi Han, Yanran Liu, Haiguang Zhao, Alberto Vomiero, Ronggui Li
Abstract
Optical nanothermometers have attracted much attention due to their non-contact and precise measurement with high spatial resolution at the micro- and nanoscales. They can be applied in various fields such as micro-opto-electronics, photonics, and biomedical thermal and pH sensing, while most thermal sensors reported so far contain heavy metals or have low sensitivity. Herein, we demonstrate a highly sensitive ratiometric thermal sensor based on colloidal C-dots. C-dots exhibit dual emission originating from the band gap emission and surface-dominant emission, which show a different temperature-dependent photoluminescence (PL) response. Among different surface-functionalized C-dots, C-dots@OH exhibit an absolute thermal sensitivity of -0.082 °C-1, which is the highest among various types of ratiometric thermosensors, making it a very promising candidate for high-sensitivity, self-calibrated nanoscale thermometry. As a proof-of-concept, C-dots@OH were employed to monitor the intracellular temperature (32-42 °C), showing a clear trend for temperature variation in a single cell, indicating that C-dots could offer a powerful tool for a potential precise measurement of the intracellular temperature. They could also be used as thermal sensors for nano-electronic and optoelectronic devices.