*Review* **Carbon Dots for Killing Microorganisms: An Update since 2019**

**Fengming Lin , Zihao Wang and Fu-Gen Wu \***

State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, 2 Sipailou Road, Nanjing 210096, China **\*** Correspondence: wufg@seu.edu.cn

**Abstract:** Frequent bacterial/fungal infections and occurrence of antibiotic resistance pose increasing threats to the public and thus require the development of new antibacterial/antifungal agents and strategies. Carbon dots (CDs) have been well demonstrated to be promising and potent antimicrobial nanomaterials and serve as potential alternatives to conventional antibiotics. In recent years, great efforts have been made by many researchers to develop new carbon dot-based antimicrobial agents to combat microbial infections. Here, as an update to our previous relevant review (C 2019, 5, 33), we summarize the recent achievements in the utilization of CDs for microbial inactivation. We review four kinds of antimicrobial CDs including nitrogen-doped CDs, metal-containing CDs, antibioticconjugated CDs, and photoresponsive CDs in terms of their starting materials, synthetic route, surface functionalization, antimicrobial ability, and the related antimicrobial mechanism if available. In addition, we summarize the emerging applications of CD-related antimicrobial materials in medical and industry fields. Finally, we discuss the existing challenges of antimicrobial CDs and the future research directions that are worth exploring. We believe that this review provides a comprehensive overview of the recent advances in antimicrobial CDs and may inspire the development of new CDs with desirable antimicrobial activities.

**Keywords:** antibacterial; bactericidal; disinfection; carbon nanodots; carbonized polymer dots

**Citation:** Lin, F.; Wang, Z.; Wu, F.-G. Carbon Dots for Killing Microorganisms: An Update since 2019. *Pharmaceuticals* **2022**, *15*, 1236. https://doi.org/10.3390/ph15101236

Academic Editor: Dimitris Tsiourvas

Received: 29 July 2022 Accepted: 20 September 2022 Published: 8 October 2022

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