Graphene quantum dots in photodynamic therapy

Jiayi Chen; Wentian Wu; Fangwei Zhang; Jiali Zhang; Hui Liu; Jing Zheng; Shouwu Guo; Jingyan Zhang

doi:10.1039/d0na00631a

Graphene quantum dots in photodynamic therapy

Nanoscale Adv. 2020 Sep 17;2(10):4961-4967. doi: 10.1039/d0na00631a. eCollection 2020 Oct 13.

Authors

Jiayi Chen¹, Wentian Wu², Fangwei Zhang², Jiali Zhang², Hui Liu¹, Jing Zheng¹, Shouwu Guo², Jingyan Zhang¹

Affiliations

¹ State Key Laboratory of Bioreactor Engineering, Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology Shanghai 200237 P. R. China zhengjing@ecust.edu.cn.
² Department of Electronic Engineering, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University Shanghai 200240 P. R. China swguo@sjtu.edu.cn.

Abstract

Graphene quantum dots (GQDs) have shown great promise in a variety of medical applications. Recently, it has been found that GQDs are also beneficial for photodynamic therapy (PDT). However, the findings of GQDs as PDT agents have been controversial in the literature. Herein, we investigate the photoactivity of single-atomic-layered GQDs by examining their ability to generate singlet oxygen (¹O₂) under irradiation and their effects on the photoactivity of photosensitizers. We demonstrate that the GQDs with lateral sizes of ∼5 or 20 nm are photo-inactive for they cannot generate ¹O₂ under irradiation of either a 660 nm laser (105 mW cm^-2) or a halogen light. Moreover, the GQDs inhibit the photoactivity of two classical photosensitizers, namely, methylene blue and methylene violet. The stronger interaction between the GQDs and the photosensitizer results in greater inhibition of GQDs. Besides, the large-sized GQDs exhibit stronger inhibition than the small-sized GQDs. The inhibitory effect of the GQDs on the photoactivity of photosensitizers is consistent with their photo-cytotoxicity. These results indicate that the single-atomic-layered GQDs are not potential PDT agents, but they may be helpful for photosensitizers by delivering them into the cells. The discrepancy between the current work and the literature is probably associated with the GQDs used.