Synthesis of Luminescent Graphene Quantum Dots with High Quantum Yield and Their Toxicity Study.

Dan Jiang,Bin Liu,Shan Xu,Zhenguo Wang,Jingli Zhu,Wen Li,Na Li,Hong Zhang,Yunping Chen,Yuriy Dedkov

doi:10.1371/journal.pone.0144906

Abstract

High fluorescence quantum yield graphene quantum dots (GQDs) have showed up as a new generation for bioimaging. In this work, luminescent GQDs were prepared by an ameliorative photo-Fenton reaction and a subsequent hydrothermal process using graphene oxide sheets as the precursor. The as-prepared GQDs were nanomaterials with size ranging from 2.3 to 6.4 nm and emitted intense green luminescence in water. The fluorescence quantum yield was as high as 24.6% (excited at 340 nm) and the fluorescence was strongest at pH 7. Moreover, the influences of low-concentration (12.5, 25 μg/mL) GQDs on the morphology, viability, membrane integrity, internal cellular reactive oxygen species level and mortality of HeLa cells were relatively weak, and the in vitro imaging demonstrated GQDs were mainly in the cytoplasm region. More strikingly, zebrafish embryos were co-cultured with GQDs for in vivo imaging, and the results of heart rate test showed the intake of small amounts of GQDs brought little harm to the cardiovascular of zebrafish. GQDs with high quantum yield and strong photoluminescence show good biocompatibility, thus they show good promising for cell imaging, biolabeling and other biomedical applications.

Highlights

Graphene quantum dots (GQDs), a kind of promising carbon-based luminescent materials, have drawn researchers attention to biomedicine fields owing to their excellent optical-electronic characteristics and superior biocompatibility
When exposed to high concentration of 200 μg/mL, the Lactate dehydrogenase release (LDH) level increased almost 50% compared with the control group, which might be speculated to be the reason that GQDs could contact with cell membrane and cause the corresponding physical membrane damage
GQDs were successfully fabricated by ameliorative photo-Fenton reaction and hydrothermal process

Summary

Introduction

Graphene quantum dots (GQDs), a kind of promising carbon-based luminescent materials, have drawn researchers attention to biomedicine fields owing to their excellent optical-electronic characteristics and superior biocompatibility. It has been reported that highly blue-luminescent GQDs were produced through hydrothermal process of GO and ammonia solution and the highest PL quantum yield was 24.6% [23].

Results

Conclusion