Doped Graphene Quantum Dots as Biocompatible Radical Scavenging Agents

Abstract

Oxidative stress is proven to be a leading factor in a multitude of adverse conditions, from Alzheimer’s disease to cancer. Thus, developing effective radical scavenging agents to eliminate reactive oxygen species (ROS) driving many oxidative processes has become critical. In addition to conventional antioxidants, nanoscale structures and metal–organic complexes have recently shown promising potential for radical scavenging. To design an optimal nanoscale ROS scavenging agent, we have synthesized ten types of biocompatible graphene quantum dots (GQDs) augmented with various metal dopants. The radical scavenging abilities of these novel metal-doped GQD structures were, for the first time, assessed via the DPPH, KMnO4, and RHB (Rhodamine B protectant) assays. While all metal-doped GQDs consistently demonstrate antioxidant properties higher than the undoped cores, aluminum-doped GQDs exhibit 60–95% radical scavenging ability of ascorbic acid positive control. Tm-doped GQDs match the radical scavenging properties of ascorbic acid in the KMnO4 assay. All doped GQD structures possess fluorescence imaging capabilities that enable their tracking in vitro, ensuring their successful cellular internalization. Given such multifunctionality, biocompatible doped GQD antioxidants can become prospective candidates for multimodal therapeutics, including the reduction of ROS with concomitant imaging and therapeutic delivery to cancer tumors.

Evaluation of Antibacterial, Antioxidant, Anti-inflammatory and Anticancer Efficacy of Titanium-Doped Graphene Oxide Nanoparticles

“…Ti/GO-NPs showed 88% for 50 µg/mL, thus Ti/GO-NPs resulted in good antioxidant properties when compared to the antioxidant studies carried out with graphene doped for various metal oxides when compared with the standard ascorbic acid which showed 10-50% at 15-65 µg/mL [34]. The antioxidant activity is typically dose-dependent in our study; as the concentration of the nanoparticles increases, the antioxidant activity also increases.…”

Gazing Beyond the Horizon: A Systematic Review Unveiling the Theranostic Potential of Quantum Dots in Alzheimer's Disease

“…Zhou et al demonstrated the ability of SeDQDs to scavenge reactive oxygen species (ROS), while SeCQDs exhibited the potential to improve memory deficits and reduce Aβ accumulation [ 26 ]. Similarly, Bhaloo et al synthesized GQDs by heteroatom doping and evaluated their radical scavenging effects, demonstrating high biocompatibility (>80% cell viability) and antioxidant abilities in various assays [ 32 ]. Notably, Al-GQDs exhibited the highest reducing power, while others showed moderate scavenging success.…”

Graphene Quantum Dots Inhibit Lipid Peroxidation in Biological Membranes

“…18,39,40 GQDs can scavenge free radicals by either transferring hydrogen atoms from the functional groups or through electron transfer and adduct formations from the graphitic basal plane. 5,39,41 Therefore, we hypothesized that GQDs inhibit peroxidation of lipids in biological membranes.…”

“…Graphene quantum dots (GQDs) are carbonaceous nanoparticles with diameters below 30 nm consisting of graphitic basal planes with oxygen-containing functional groups around their outer periphery. − Depending on the starting material and synthesis method, GQDs can contain varying extents of heteroatom doping within the basal plane, − as well as different oxidation states − and degrees of surface charge within the peripheral functional groups. Over the past decade, GQDs have been researched extensively for biomedical applications due to their high biocompatibility, , especially when compared to other graphene-based nanomaterials such as large graphene oxides, − and carbon nanotubes, , which have been associated with acute toxicity in numerous studies.…”

“…While these observations imply that GQDs protect mitochondria from oxidative stress, the mechanisms by which GQDs interact with biological membranes is not fully understood. Notably, GQDs have been proposed to have antioxidant properties. ,, GQDs can scavenge free radicals by either transferring hydrogen atoms from the functional groups or through electron transfer and adduct formations from the graphitic basal plane. ,, Therefore, we hypothesized that GQDs inhibit peroxidation of lipids in biological membranes.…”