Size-Dependent Interactions of γH2AX and p53 Proteins with Graphene Quantum Dots

p53 protein is a nuclear phosphoprotein that is a critical tumor suppressor, playing a key role in regulating the cell cycle and initiating apoptosis in response to DNA damage. As a transcription factor, it also activates genes involved in DNA repair and cell cycle arrest. H2AX is a histone H2A variant, which is vital for detecting DNA double-strand breaks. When phosphorylated at Serine 139, it forms γH2AX, which recruits DNA repair proteins to damage sites. The interaction between p53 and γH2AX is central to the DNA damage response, where p53 activates repair pathways and γH2AX flags the DNA lesions. It is known that impairing γH2AX while preserving p53 activity may slow cancer progression. Towards understanding this, graphene quantum dots (GQDs) offer a promising solution for tracking γH2AX and analyzing DNA damage, where they can help visualize it by investigating how p53 contributes to DNA repair at sites marked by γH2AX. This study examines the interactions between γH2AX and p53 with three different-sized two-layered GQDs (2 × 3 nm, 5 × 6 nm, and 8 × 9 nm) using the Molecular Dynamics (MD) approach. Our analysis revealed that both proteins adsorbed strongly to the 5 × 6 nm and 8 × 9 nm GQDs, with 5 × 6 nm GQD having the highest stability, making it a key candidate for future biosensing and cancer research, whereas the 8 × 9 nm GQD has the greatest potential to denature the proteins.