Antimicrobial and Nanocarrier Properties of Carbon Dots (CDs) Synthesized from Different Materials

Asmita Devkota, Tennessee State University


Multidrug resistance (MDR) in pathogens is a serious public health issue. In this prospect, the use of carbon dots as an antimicrobial agent is promising as they lead to nonspecific and random oxidative damages to the biomolecules such as proteins, lipids, and nucleic acids. Moreover, CDs are excellent candidates for gene delivery owing to their unique features like a facile synthesis, ease of functionalization, non-toxicity, and greater biocompatibility. The efficient way of introducing exogenous DNA into bacterial cells is fundamental in many microbiology and molecular activities such as cloning, mutant generation, DNA library construction. Heat shock and electroporation are two major techniques of gene delivery in bacterial cells, however, both techniques are time and resource-consuming. Thus, to develop efficient, easy, less time-consuming, and safe gene delivery methods, we used carbon dots as a non-viral method of gene delivery. In this study, we synthesized four carbon dots: amine-coated carbon dots (NH2-FCDs), carboxylate carbon dots (COOH-FCDs), carbon dots from L-arginine, and glucose (N-CDs), and carbon dots using citric acid and polyethyleneimine (PEI). We studied their antimicrobial effects in six different bacteria viz E. coli, Pectobacterium carotovorum, Agrobacterium tumefaciens, Agrobacterium rhizogenes, Pseudomonas syringae, and Salmonella enterica. Further, we studied the plasmid/gene delivery efficiency of carbon dots inside Escherichia coli, Pectobacterium carotovorum, and Salmonella enterica. We incubated CDs, cells, and plasmids carrying red fluorescent protein (RFP) as a reporter gene and ampicillin resistance gene as selectable markers. We used the agar well diffusion method for the antimicrobial study and calculated the inhibition zones in each bacterium. Transformed colonies were counted using ImageJ software and data were analyzed using R-software. Our findings showed that amine-coated carbon dots (NH2-FCDs) showed the highest inhibition in bacteria whereas carbon dots prepared from citric acid and polyethyleneimine (PEI) were non-inhibitory to the cells. Salmonella and E. coli were more resistant against CDs compared to Agrobacterium, Pseudomonas, and Pectobacterium. Different incubation times were also required for complete inhibition of bacteria according to the source of carbon dots. Similarly, our study demonstrated that among all these CDs, only carboxylate carbon dots (COOH-FCDs) were able to deliver plasmid DNA into E. coli cells.

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Recommended Citation

Asmita Devkota, "Antimicrobial and Nanocarrier Properties of Carbon Dots (CDs) Synthesized from Different Materials" (2021). ETD Collection for Tennessee State University. Paper AAI28648038.