RUI: Collaborative Research: Microbicidal Carbon Dots for Combating Anti-Biotic Resistance and Beyond

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Non-Technical Abstract: Since the 1990s, infectious diseases caused by antibiotic-resistant bacteria have been increasing globally and becoming a serious threat from these diseases. Antibiotic resistance is mostly a consequence of bacterial response to excessive uses of antibiotics in humans or agriculture and the widespread usage of disinfectants in a variety of other settings. Noticeably, new resistance mechanisms emerge and spread globally as fast as new drugs being developed, which has posted serious challenges to the realm of traditional antibiotics/antimicrobial agents, but has also motivated a global search for alternative antimicrobial strategies. Among the many strategies that have been pursued in combating the resistance, the development of antibacterial agents that are mechanistically different from traditional antibiotics is a more effective option. Specifically, on the technology explored in this project, carbon dots are developed as a new class of antimicrobial agents which kill bacterial cells through reactive species generated under visible/natural light. This project, funded by the Biomaterials Program within the National Science Foundation's Division of Materials Research, focuses on the evaluation and validation of the potential of carbon dots for killing drug-resistant bacteria and developing an understanding of related working mechanisms, with the goal of establishing an effective alternative antimicrobial technology for combating drug-resistant bacteria. This project will also have significant broader impacts in stimulating the development and transfer of new technologies for the knowledge-driven economy, and other areas such as applications in food, water safety and national defense, education and human resource development. With more than 85% of the student population from underrepresented minority groups, the proposed multidisciplinary research is expected in providing a great research training environment for these undergraduate students in a variety of ways, including direct participation in research, student exchange programs (between the collaborators' labs), and summer workshops. Technical Abstract: This Collaborative Research project is to explore the light-activated microbicidal functions of newly developed carbon dots (CDots) against drug-resistant bacterial pathogens. CDots may be considered as a special kind of "core-shell" nanostructures, each with a small carbon nanoparticle core and a thin shell of soft materials. They are strongly absorptive over the entire visible spectrum, and their photoexcited state properties and redox processes resemble those typically found in semiconductor quantum dots, but with unique advantages. The interdisciplinary project team will develop and validate CDots as a new class of visible/natural light-activated microbicidal agents against multi-drug resistant bacteria, with the selected species for testing including Salmonella enterica, Listeria monocytogenes, and Campylobacter jejuni and Campylobacter coli isolated from farm animals. The scientific objectives of the project are: (1) systematic evaluation of CDots' antibacterial function to the drug-resistant bacteria in relation to several major factors including Cdot surface charge, size, and synthesis approach; (2) mechanistic elucidation and understanding of CDots' antimicrobial function, focusing on correlations of the structural and photochemical parameters of CDots with the observed bacteria-killing performances; and (3) exploration of Carbon/TiO2 hybrid dots of different configurations for enhanced antimicrobial performance against drug-resistant microbes and viruses. The intellectual merits of the project include the advancement of the biomaterial field for antimicrobial applications and the establishment of the photo-activated antimicrobial functions of CDots for combating the increasing threat of antibiotic resistance. In addition to addressing the critical issues in national healthcare, these materials could find applications in food, water safety and national defense. The broad impacts of the project include providing excellent research-for-training opportunities for participating students in the interdisciplinary field at the interface of material science and biological applications at the two collaborating institutions, especially for undergraduate and K-12 students from underrepresented groups.