Recent Advances in Carbon Nanodots: A Promising Nanomaterial for Biomedical Applications

Abstract

Carbon nanodots (CNDs) are an emerging class of nanomaterials and have generated much interest in the field of biomedicine by way of unique properties, such as superior biocompatibility, stability, excellent photoluminescence, simple green synthesis, and easy surface modification. CNDs have been featured in a host of applications, including bioimaging, biosensing, and therapy. In this review, we summarize the latest research progress of CNDs and discuss key advances in our comprehension of CNDs and their potential as biomedical tools. We highlighted the recent developments in the understanding of the functional tailoring of CNDs by modifying dopants and surface molecules, which have yielded a deeper understanding of their antioxidant behavior and mechanisms of action. The increasing amount of in vitro research regarding CNDs has also spawned interest in in vivo practices. Chief among them, we discuss the emergence of research analyzing CNDs as useful therapeutic agents in various disease states. Each subject is debated with reflection on future studies that may further our grasp of CNDs.

ROS-Scavenging Therapeutic Hydrogels for Modulation of the Inflammatory Response

“…Carbon nanomaterials such as fullerene, carbon nanotube (CNT), and carbon nanodots also exhibit effective ROS-scavenging properties but use different mechanisms. , They can interact with superoxide anions because of high electron affinity through π- π stacking and convert them to O 2 by transferring an electron. , In this case, the electron- π system allows the carbon nanomaterials to work as electron donors (Figure d) . In contrast, when they are modified with surface functional groups with more hydrophilicity such as hydroxyl, aldehyde, and amine, these functional groups behave as proton donors .…”

“…186,187 In this case, the electron-π system allows the carbon nanomaterials to work as electron donors (Figure 4d). 188 In contrast, when they are modified with surface functional groups with more hydrophilicity such as hydroxyl, aldehyde, and amine, these functional groups behave as proton donors. 185 When it is possible to transfer electrons from ROS to carbon backbones, carbon releases acidic residues such as carbonates and bicarbonates as products of degradation.…”

Nitrogen-Doped Carbon Dots with Oxidation Stress Protective Effects for Reactive Oxygen Species Scavenging on Hepatic Ischemia–Reperfusion Injury

“…Recently, the swift progression of precision medicine and targeted therapies has led to the increasing popularity of nanomaterials in medical research, either as drugs or drug carriers. − Nanomaterials such as Prussian blue, carbohydrate-derived nanoantioxidants, and platinum nano-antioxidant were employed to explore their protective effects on HIRI. Compared to the aforementioned nanomaterials, chitosan-derived nitrogen-doped carbon dots (CNDs) offer advantages such as simpler size control, excellent bioluminescence, high biocompatibility, and a plethora of surface functional groups. − These attributes make them potential candidates for fluorescent localization and as drug carriers, positioning them as versatile nanomaterials for broader applications. From the perspective of molecular structure, the conjugated π system or carboxyl group in CNDs serves as a special electron donor, granting them a unique ability to scavenge reactive oxygen free radicals, particularly hydroxyl radicals (OH•) which are difficult to transfer within cells .…”

Carbon Quantum Dots from Amino Acids Revisited: Survey of Renewable Precursors toward High Quantum-Yield Blue and Green Fluorescence

“…Carbon quantum dots (CQDs) are fluorescent nanomolecules or nanoparticles smaller than 10 nm. , The most studied 0D CQDs consist of a more graphitized, sp 2 -carbon rich core surrounded with a 5–50 wt % amorphous shell of polar functional groups. − The structure of CQDs results in their excellent solubility in water, negligible cytotoxicity, and biocompatibility, and while bearing carboxylic groups, CQDs are conveniently functionalizable . CQDs combine the unique optical properties of quantum dots (QDs) with the electronic properties of carbon (nano)­materials.…”