Poor mechanical properties and bacterial infection are the main problems faced by dental restorative resins in clinical use. In this study, graphene quantum dots (GQDs) grafted with imidazole groups and mesoporous silica (MSN) are co-filled in a dental resin to impart excellent antimicrobial activity and mechanical properties to the dental resin. The higher specific surface area of GQDs and MSN results in an increased contact area with the resin matrix, which enhances the strength of the dental composite resin. The introduction of GQDs significantly improves the antimicrobial activity of the resin. The inhibition efficiency of the composite resin against Streptococcus mutans reached 99.9% with the addition of GQDs at only 0.2 wt.%. When MSN and GQDs are co-filled, MSN interferes with the release of GQDs, thus reducing the antimicrobial activity of the dental resin but improving the cyto-compatibility. By reasonably adjusting the amount of GQDs and MSN, the dental composite resin can exhibit excellent antimicrobial properties, mechanical properties and cyto-compatibility at the same time.

    Abstract
    1 Introduction
    2 Materials and methods
        2.1 Preparation of GQDs and MSN
        2.2 Silanization of GQDs and MSN
        2.3 Preparation of composite resins
        2.4 Characterization of GQDs, MSN and the composite resins
        2.5 Mechanical properties
        2.6 In vitro antibacterial property
        2.7 Cyto-compatibility
        2.8 Statistical analysis
    3 Results and discussion
        3.1 Characterization of GQDs and MSN
        3.2 Characterization of the composite resins
        3.3 Mechanical properties of composite resins
        3.4 Antimicrobial property
        3.5 Cyto-compatibility
    4 Conclusion
    Acknowledgements 
    References

• Shuxin Lu(Shanxi Key Laboratory of Biomedical Metal Materials, College of Materials Science and Engineering, Taiyuan University of Technology)
• Hongyu Zhang(Department of Occupational Disease, Second Hospital of Shanxi Medical University)
• Maozhou Chai(College of Biomedical Engineering, Taiyuan University of Technology)
• Xiaohong Yao(Shanxi Key Laboratory of Biomedical Metal Materials, College of Materials Science and Engineering, Taiyuan University of Technology)
• Xiangyu Zhang(Shanxi Key Laboratory of Biomedical Metal Materials, College of Materials Science and Engineering, Taiyuan University of Technology)
• Yongqiang Yang(National Graphene Products Quality Inspection and Testing Center (Jiangsu))