Oral Defense Examination : Engineering Metal Nanoclusters for Enhanced Antimicrobial Effects and Their Mechanism Study

Speaker Zheng Kaiyuan (Supervisor: A/Prof Xie Jianping)

Host Department of Chemical and Biomolecular Engineering

Date/Time 20 Nov - 20 Nov, 2.00PM

Venue E5-02-32 , Faculty of Engineering, National University of Singapore


Antimicrobial resistance is one of the greatest health threats worldwide, so alternative powerful antimicrobial agents are urgently needed. The silver (Ag) nanomaterials are attractive broad-spectrum antimicrobial agents. We summarized the physicochemical properties of Ag nanomaterials, and found that size could determine antimicrobial efficiency. Therefore, we used ultrasmall metal nanoclusters (NCs) less than 2 nm as model to improve antimicrobial efficiency. Firstly, we synthesized ultrastable luminescent Ag NCs through aggregation-induced emission (AIE). Next, we improved antimicrobial efficiency through conjugation of Ag NCs with a commercial antibiotics daptomycin to achieve synergistic effects. The conjugation could effectively kill bacteria with complementary antimicrobial mechanisms. Moreover, commonly believed inert and noble gold (Au) was found to show unexpected antimicrobial effect in Au NCs form. The Au NCs could kill both Gram-positive and Gram-negative bacteria by generating reactive oxygen species (ROS), thus disturbing the normal metabolism of bacteria to kill them. In addition, we found the surface ligand of Au NCs could influence their antimicrobial efficiency, and the mechanism behind was explored.