Red, Yellow, and Blue Luminescence by Graphene Quantum Dots: Syntheses, Mechanism, and Cellular Imaging

Abstract

Owing to their excellent photoluminescence (PL) properties, good biocompatibility, and low toxicity, graphene quantum dots (GQDs) are widely applied in bioimaging, biosensing, and so forth. However, further development of GQDs is limited by their synthetic methodology and unclear PL mechanism. Therefore, it is urgent to find efficient and universal methods for the synthesis of GQDs with high stability, controllable surface properties, and tunable PL emission wavelength. By coating with polyethyleneimine (PEI) of different molecular weights, blue-, yellow-, and red-emitting GQDs were successfully prepared. By transmission electron microscopy, atomic force microscopy, and dynamic light scattering, the characterization of size and morphology revealed that blue-emitting PEI GQDs were monocoated, like jelly beans, and red-emitting PEI GQDs were multicoated, like capsules. The amidation reaction between carboxyl and amide functional groups played an important role in the coating process, as evidenced by IR spectroscopy and theoretical calculation with density functional theory B3LYP/6-31G*. The PL-tunable GQDs exhibited an excellent chemical stability and extremely low cytotoxicity, and they had been shown to be feasible for bioimaging, making these GQDs highly attractive for a wide variety of applications, including multicolor imaging and bioanalysis.

Carbon and graphene quantum dots: a review on syntheses, characterization, biological and sensing applications for neurotransmitter determination

“…As a result, the mentioned procedures have been affordable, and also yield exact dimension control, allowing the natural inheritance of the heteroatoms from the precursors. 68 2.2.2.2. Cage opening of fullerene.…”

Solvent‐Controlled Synthesis of Highly Luminescent Carbon Dots with a Wide Color Gamut and Narrowed Emission Peak Widths

“…To this aim, the relationships between the typical excitation dependent/independent emission features and the complicated structures/compositions of CDs should be understood deeply, which involve the particle sizes, the sp 2 carbon framework, the graphitization degree, the heteroatom doping, organic groups, surface states, etc . Several research groups have prepared CDs with gradually tuned optical properties by varying carbon sources and reaction conditions, and tried to correlate the PL features of CDs with their particle sizes, element contents, and functional groups.…”

Self‐Quenching‐Resistant Red Emissive Carbon Dots with High Stability for Warm White Light‐Emitting Diodes with a High Color Rendering Index

“…Carbon dots (CDs), an emerging class of carbon‐based luminescent nanomaterials, have attracted more and more attention and interest in recent years owing to their outstanding properties, such as chemical stability, [ 10,11 ] photostability, [ 12–14 ] biocompatibility, [ 15,16 ] and low toxicity. [ 17–19 ] Because of those distinct merits, CDs could be able to apply in extensive fields, such as drug delivery, [ 20,21 ] solar cell, [ 22 ] optoelectronic devices, [ 23,24 ] bioimaging, [ 25,26 ] and so on.…”