Improvement of Photoluminescence of Graphene Quantum Dots with a Biocompatible Photochemical Reduction Pathway and Its Bioimaging Application

Abstract

As a rising star in the family of fluorescent material, graphene quantum dots (GQDs) have attracted great attention because of their excellent properties such as high photostability against photobleaching and blinking, biocompatibility, and low toxicity. Herein, blue luminescent GQDs were prepared by photo-reducing GQDs with isopropanol. After photochemical reduction, the increasing of sp(2) domains and the formed hydroxyl in pGQDs can enhance the photoluminescence of GQDs. The quantum yield of the photo-reduced GQDs (pGQDs) was increased 3.7 fold. Because of its less negative surface charges and lower cytotoxicity than chemical reduced GQDs (cGQDs), the pGQDs were more easily uptaken by cells. This work may provide a simple and green pathway to enhance the QY of GQDs with satisfactory biocompatibility as fluorescent nanoprobes.

Photoluminescent and superparamagnetic reduced graphene oxide–iron oxide quantum dots for dual-modality imaging, drug delivery and photothermal therapy

“…This led to the development of biocompatible carbon-based QDs, with QDs derived from carbohydrates [20], nanodiamonds [21], and graphene [22][23][24][25]. Graphene QDs (GQDs) can be created by ultrasonication [22], chemical reduction [23], photo-reduction [24], and hydrothermal cutting [25]. These carbon QDs emit the same level of luminescence as the cadmium QDs, but do not carry the same cytotoxic risk.…”

Properties and Synthesis Strategies of Graphene Quantum Dots

“…In this regard, post-modification is an alternative approach, in which GQDs can be modified by post-processing. 58,[60][61][62][63][64][65][66][67][68] Post-modification allows one to design GQDs with rationally improved properties. Polymer passivation is an often-adopted method to improve the quantum yield of GQDs.…”

Nanofabrication of Graphene Quantum Dots with High Toxicity Against Malaria Mosquitoes, Plasmodium falciparum and MCF-7 Cancer Cells: Impact on Predation of Non-target Tadpoles, Odonate Nymphs and Mosquito Fishes

“…This interaction helps GQDs to decrease the cell viability by alterations in the nuclear morphology, cytoplasm organization, and changes in gene expression of MCF-7 cells. Nitrogen-doped GQDs were co-cultured with HeLa cells and did not showed considerable toxicity on HeLa cells by 3-(4, 5-dimeth-ylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide test (MTT) assay [60], see also [70]. To our mind, GQDs are a possible candidate to inhibit tumor progression and thereby effectively controlling the disease progression without toxicity towards normal cells.…”