Je Min Yoo

Graphene quantum dots (GQDs) constitute the zero-dimensional family of carbon nanomaterials, combining efficient penetration of the blood–brain barrier (BBB) with precisely controllable surface chemistry, and have drawn attention as theragnostic platforms that carry both diagnosis and therapy in a single particle. Although various neurodegenerative diseases each arise from a different causal protein, they converge on shared pathology: aberrant accumulation of neuronal proteins and chronic neuroinflammation driven by pathological activation of glial cells such as microglia and astrocytes. GQDs modulate aggregation through monomer capture that delays nucleation, the blockade of growing fibril tips, and the penetration and disassembly of mature fibrils, all of which have been verified against various protein aggregation models. Beyond aggregation control, heteroatom doping and surface functionalization design allow GQDs to scavenge reactive oxygen species (ROS) and adjust autophagic pathways, attenuating markers of pathological microglial activation. Tunable emission simultaneously enables imaging of pathological burden and high-sensitivity detection of fluid biomarkers, supporting integration of therapeutic and diagnostic functions. GQD bioactivity, however, is inherently double-edged: depending on composition and concentration, the same materials can trigger mitochondrial oxidative stress and ferroptosis rather than exerting antioxidant action, as observed in microglia and macrophages. Therefore, key challenges remain separating anti-inflammatory efficacy from toxicity through precise surface functionalization, ensuring batch-to-batch reproducibility, establishing standardized physicochemical reporting, and quantitatively delineating the therapeutic window.

Aberrant phase separation- and stress granule (SG)-mediated cytosolic aggregation of TDP-43 in motor neurons is the hallmark of amyotrophic lateral sclerosis (ALS). In this study, we found that graphene quantum dots (GQDs) potentially modulate TDP-43 aggregation during SG dynamics and phase separation. The intrinsically disordered region in the C-terminus of TDP-43 exhibited amyloid fibril formation; however, GQDs inhibited the formation of amyloid fibrils through direct intermolecular interactions with TDP-43. These effects were accompanied by attenuation of the ALS phenotype in animal models. Additionally, GQDs delayed the onset and survival of TDP-43 transgenic mouse models by enhancing motor neuron survival, reducing glial activation, and reducing the cytosolic aggregation of TDP-43 in motor neurons. In this research, we demonstrated the efficacy of GQDs on the SG-mediated aggregation of TDP-43 and the binding property of GQDs with TDP-43. Additionally, we demonstrated the clinical feasibility of GQDs using several animal models and other types of ALS caused by FUS and C9orf72. Therefore, GQDs could offer a new therapeutic approach for proteinopathy-associated ALS.

Recent studies concerning graphene quantum dots (GQDs) focus extensively on their application in biomedicine, exploiting their modifiable optical properties and ability to complex with various molecules via π–π or covalent interactions. Among these nascent findings, the potential therapeutic efficacy of GQDs was reported against Parkinson’s disease, which has to date remained incurable. Herein, we present an environmentally friendly approach for synthesizing GQDs through a waste-to-treasure method, specifically from coffee waste to nanodrug. Consistent with the previous findings with carbon fiber-derived GQDs, the inhibitory effects of coffee bean-derived GQDs demonstrated similar effectiveness against abnormal α-synuclein fibrillation and the protection of neurons from relevant subcellular damages. The fact that a GQDs-based nanodrug can be prepared from a non-reusable yet edible source illustrates a potential approach to convert such waste materials into novel therapeutic agents with minimal psychological rejection by patients.

In the field of wastewater treatment, the advanced oxidation process (AOP) is a widely employed method. It uses reactive oxygen species (ROS) to degrade harmful organic and inorganic chemicals. Metal catalysts are the conventional standard when using these methods. However, they have drawbacks such as harsh activation conditions and poor recyclability. We previously suggested chemical vapor deposition (CVD) graphene film as an alternative metal-free catalyst. In this study, we enhanced the catalytic activity of the CVD graphene film by synergistically adding UV light irradiation. The result was complete degradation of phenol on a wafer-scale in a reduced timeframe. To further enhance the degradation process, we devised a graphene-based column for continuous in situ chemical oxidation and analyzed the intermediates over time, proving the potential of graphene-assisted AOP in industrial wastewater applications.

While graphene and its derivatives have been suggested as a potential nanomedicine in several biomimetic models, their specific roles in immunological disorders still remain elusive. Graphene quantum dots (GQDs) may be suitable for treating intestinal bowel diseases (IBDs) because of their low toxicity in vivo and ease of clearance. Here, GQDs are intraperitoneally injected to dextran sulfate sodium (DSS)–induced chronic and acute colitis model, and its efficacy has been confirmed. In particular, GQDs effectively prevent tissue degeneration and ameliorate intestinal inflammation by inhibiting T_H1/T_H17 polarization. Moreover, GQDs switch the polarization of macrophages from classically activated M1 to M2 and enhance intestinal infiltration of regulatory T cells (T_regs). Therefore, GQDs effectively attenuate excessive inflammation by regulating immune cells, indicating that they can be used as promising alternative therapeutic agents for the treatment of autoimmune disorders, including IBDs.

This communication proposes the use of monolayer CVD graphene as a novel metal-free catalyst for degradation of phenols.

We report the synthesis and applications of APPE (aminophenyl propargyl ether) as a novel n-type dopant for graphene. The characteristics of APPE-doped graphene films were investigated using Raman spectroscopy as well as electron transport measurements. The Raman 2D/G peak ratio decreased by more than 40%, and the minimum conductivity voltage (Dirac voltage) was shifted to −133 V as the pristine graphene was doped with APPE, indicating that the graphene was strongly n-doped. We suppose that the electron donating property of the amine group (–NH₂) is the origin of such an intense n-doping effect. In contrast, a similar molecule with an electron withdrawing nitro group (–NO₂) (nitrophenyl propargyl ether, NPPE) showed a slight p-doping effect. Thus, we conclude that the doping effect of a molecular framework strongly depends on the functional substituents, which can be represented by the Hammett equation. We also confirmed that the sheet resistance of the APPE doped graphene film was reduced by ∼70%, which is crucial to enhance the electrical conductivity of graphene for various electronic applications. In addition, the acetylene group of APPE appears promising to be utilized in “click chemistry” to further functionalize the π-surface of graphene for sensors and bio applications.