摘要： Background: Recently, antimicrobial photodynamic therapy (aPDT) as an alternative treatment modality has been used adjunctively in the treatment of periodontitis and peri-implantitis. Photosensitizing agents in the form of nanoparticles have been designed for improving the e?ciency of aPTD. Graphene quantum dots are a special type of nanocrystals that can promote aPDT when coupled with curcumin (Cur). The main objective of the present study was to investigate the e?ects of photoexcited GQD-Cur on the metabolic activity of perio-pathogen mixed bio?lms. Materials and methods: GQD-Cur was synthesized and characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS), fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible spectrometry (UV–Vis), and X-ray di?raction (XRD). The cell cytotoxicity e?ect of GQD-Cur was evaluated on primary human gingival ?broblast (HuGu) cells. Perio-pathogen mixed bio?lms including Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia photosensitized with GQD doped with Cur were irradiated with a blue LED at a wavelength of 435 ± 20 nm for 1 min, and then bacterial viability measurements were performed. The antimicrobial susceptibility pro?le, bio?lm formation ability, amount of reactive oxygen species (ROS) released, and variations of gene expressions involved in bio?lm formation were assessed. Results: The SEM, DLS, FTIR, UV–Vis spectrometry, and XRD pattern con?rmed that GQD-Cur was synthesized successfully. According to the results, GQD-Cur exhibited no cytotoxicity against HuGu cells. Photoexcited GQD-Cur resulted in a signi?cant reduction in cell viability (93%) and bio?lm formation capacity (76%) of peri-pathogens compared to the control group (P < 0.05). According to the results, a signi?cant concentration-dependent increase in the ROS generation was observed in perio-pathogens mixed cells treated with di?erent doses of GQD-Cur-aPDT. Moreover, rcpA, ?mA, and inpA gene expression pro?les were downregulated by 8.1-, 9.6-, and 11.8-folds, respectively. Conclusions: Based on the results, photoexcited GQD-Cur have a high potency of perio-pathogens suppression in planktonic and bio?lm forms and downregulation of the bio?lm genes expression pattern was exploited as a nanoscale-based platform for periodontitis.