Recent Advances on Graphene Quantum Dots for Bioimaging Applications

Abstract

Being a zero-dimensional (0D) nanomaterial of the carbon family, graphene quantum dots (GQDs) showed promising biomedical applications owing to their ultra-small size, non-toxicity, biocompatibility, excellent photo stability, tunable fluorescence, and water solubility, etc., thus capturing a considerable attention in biomedical field. This review summarizes the recent advances made in the research field of GQDs and place special emphasis on their bioimaging applications. We briefly introduce the synthesis strategies of GQDs, including top-down and bottom-up strategies. The bioimaging applications of GQDs are also discussed in detail, including optical [fluorescence (FL)], two-photon FL, magnetic resonance imaging (MRI), and dual-modal imaging. In the end, the challenges and future prospects to advance the clinical bioimaging applications of GQDs have also been addressed.

Preparation and Applications of Carbon‐Based Fluorescent Nanothermometers

“…GQDs are zero‐dimensional nanomaterials of the carbon family, consisting of a single atom–thick sheet of honeycomb structure. [ 47–54 ] At present, the GQD synthesis methods can be divided into top–down and bottom–up approaches. [ 47,48,51 ] In the top–down synthesis method, the bulk carbon materials, such as graphene and carbon black, are usually cracked by chemical/electrochemical exfoliation, hydrothermal/solvothermal treatment, and microwave/ultrasonic treatment to produce nano‐quantum dots.…”

“…They show the following advantages: high optical absorptivity, adjustable fluorescent emission, chemical stability, well biocompatibility, and low toxicity. [ 5–99 ] Given these superior properties, they have been extensively discussed in bioimaging devices, biosensors, catalysts, photovoltaic devices, as well as fluorescent nanothermometers for spatially resolved temperature ( Figure ). [ …”

Graphene Quantum Dots as Flourishing Nanomaterials for Bio-Imaging, Therapy Development, and Micro-Supercapacitors

“…Currently, PSs do not only attack the targeted malignant cells, but as light irradiation must be implemented for target treatment, this can also generate ROS in both normal and healthy cells, damaging them irreparably [ 191 ]. Nevertheless, the use of GQDs may assist on overcoming the previously mentioned challenges of choosing the ideal PS due to their excellent catalytic activity, genuine fluorescence properties, and good photo stability [ 192 ].…”

Graphene-Based Scaffolds for Regenerative Medicine

“…Some biosensors integrate graphene in the surface plasmon resonance (SPR) technology, showing improved sensitivity and detection range [ 10 ]. Graphene quantum dots (GQDs) are of special interest to bioimaging in vitro and in vivo because of their biocompatibility, tunable fluorescence with excellent photostability, ultra-small size and hydrophilicity [ 11 ]. Stable photoluminescence makes GQDs suitable for cancer bioimaging and has led to biofunctionalization for specific cancer cell imaging and real-time imaging in living cells [ 12 ].…”