Selective eradication of pathogenic bacteria using amine-modified corn-straw carbon dots.

Area of Science:

• Biomaterials Science
• Nanotechnology
• Environmental Science

Background:

• Antimicrobial resistance (AMR) and the ecological damage from broad-spectrum disinfectants necessitate targeted antibacterial strategies.
• *Staphylococcus aureus* ( *S. aureus* ) is a resilient pathogen found in aquatic environments, posing significant health risks and contributing to AMR.
• Current disinfectants lack the specificity to eliminate *S. aureus* without impacting beneficial microbial communities.

Purpose of the Study:

• To develop a species-specific antimicrobial agent for precise elimination of *S. aureus*.
• To utilize agricultural waste for creating sustainable and effective nanomaterials for pathogen control.
• To investigate the mechanism of selective bacterial eradication by novel carbon dot-based agents.

Main Methods:

• One-step hydrothermal synthesis of triethylenetetramine-functionalized carbon dots from corn straw biomass.
• Assessing bactericidal efficacy against *S. aureus* at various concentrations, temperatures, and time points.
• Investigating the mechanism of action, including cell-wall binding, membrane disruption, and reactive oxygen species (ROS) generation (superoxide and singlet oxygen).
• Evaluating selectivity by testing against *Bacillus subtilis*, *Escherichia coli*, and *Pseudomonas aeruginosa*.

Main Results:

• Synthesized carbon dots exhibit intrinsic oxidase-like activity, selectively eliminating *S. aureus* with 100% efficacy at 50 μg mL^-1 within 1 hour at 37 °C.
• The nanomaterials retain significant activity (80%) even at 4 °C.
• Selective bacterial killing is achieved through synergistic binding to cell-wall polysaccharides and membrane disruption, coupled with ROS generation.
• The agent spares beneficial bacteria like *B. subtilis* and Gram-negative species (*E. coli*, *P. aeruginosa*) due to cell-wall differences.
• Amine chain length on carbon dots modulates oxidase activity and ROS production.
• The carbon dots are rapidly photodegradable within 11 days under visible light.

Conclusions:

• Triethylenetetramine-functionalized carbon dots derived from agricultural waste offer a sustainable and selective method for controlling *S. aureus*.
• The nanomaterials' mechanism involves preferential binding and ROS generation, ensuring ecological compatibility.
• This approach advances the design of next-generation nano-antimicrobials with tunable properties for targeted pathogen eradication.