报告题目：Graphene quantum dots: fluorescent properties and biomedial applications

报告人：Nikita Belko¹

1-B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, 220072 Minsk, Belarus

Email: nikita.belko@gmail.com (nikita.belko@qq.com)

报告时间：2023年8月26日上午10：00 – 11：00

报告地点：激光楼116（多功能厅）

报告邀请人：李念强教授

报告人简介：

Nikita Belko received his Ph.D. degree in optics from the Belarusian State University in 2021. His research interests include optical spectroscopy, carbon-based nanomaterials, and ghost imaging.

报告摘要：

Graphene quantum dots (GQDs) are biocompatible carbon-based nanomaterials with a small size (~5 nm) and remarkable luminescent properties. The potential of GQDs for both in vitro and in vivo bioimaging has been demonstrated in numerous reports. Here, we study fluorescent properties of commercially available and standardized GQDs [green luminescent, water-dispersed, CAS 7440−44−0, Sigma-Aldrich] in different environments. We demonstrate, in contrast to many reports, that this kind of GQDs suffers from substantial photoinstability and exhibits rather fast photobleaching under visible light irradiation. For the GQDs immobilized on a solid substrate, in a polymer matrix, or in dried red blood cell (RBC) membranes, the emission signal is slowly recovering in the dark, and this process can be accelerated by decreasing the temperature. These GQD samples demonstrate dynamic hysteresis in fluorescence intensity under optical excitation by long (10–100 s) symmetrical triangular pulses. In addition, all of these samples exhibit exponential distribution of photon-waiting times in photon-counting measurements indicating that the emission statistics is not affected by the microenvironment and the dots emit independently. In aqueous suspensions, the GQDs undergo irreversible photodegradation. Nevertheless, the GQDs can be considered a good fluorescent label for the applications where the prolonged photostability is not essential. In fact, the studied GQDs were shown to efficiently accumulate in RBC membranes and exhibit bright fluorescence without compromising the viability of the cells.