Abstract
<title>Abstract</title> <p>To evaluate novel functionalized graphene quantum dots (G-QDs) and determine their effects on dentin crystal orientation, mechanical properties, and adhesive bonding. Dentin blocks (4 mm × 4 mm × 3 mm) were used to create artificial caries-like lesions. Graphene-based treatment solutions were prepared at 0.1%, 0.2%, 0.3%, and 0.5% G-QDs (G-QDs0.1%, G-QDs0.2%, G-QDs0.3%, G-QDs0.5%.), with 0.9% saline serving as the vehicle control (controlG-QDs00). Molecular geometries were obtained from PubChem database and optimized with a semiempirical approach and atom labeling. Specimens were immersed in solutions for 1-month and then challenged with artificial saliva/collagenase cocktail for 3 days at 37°C. Treated dentin was characterized by TEM/XRD/O-PTIR/Raman spectroscopy/AFM-based mechanical testing, microtensile bond strength (μTBS), and glutamate quantification. Docking indicated higher affinity of G-CQD for collagen than for HAp. Quantum mechanical calculations suggested grafting of phenylalaninyl proline dipeptide groups to graphene oxide surface. Raman analysis showed concentration-dependent shifts at 1450, 1453, 1457, 1460, and 1462 cm−1 for control and G-QD groups, respectively. TEM demonstrated preserved collagen fibril organization in G-QDs0.5% specimens, with fibrillar collagen molecules having an estimated molecular length approximately 4.4 times the D-period. G-CQDs showed higher glutamate concentrations (p<0.05). O-PTIR ratio maps and indicated local matrix-to-mineral changes. XRD/Rietveld refinement showed increased crystallinity and altered atomic site occupancies, especially in G-QD groups who showed higher stiffness than control. μTBS decreased after aging in all groups except G-QDs0.5%. 0.5% G-QD modification improved dentin physicochemical and structural features and may contribute to a more stable adhesive-dentin interface.</p>