# Enhancement of Antibacterial Activity of Carbon Dots via Lysozyme Coupling

## TL;DR

Researchers improved the antibacterial properties of carbon dots by coupling them with lysozyme, making them safer and more effective for medical use.

## Contribution

Lysozyme coupling enhances the biocompatibility and antibacterial duration of carbon dots.

## Key findings

- Coupled carbon dots showed increased water dispersibility and particle sizes between 12 to 20 nm.
- Cytotoxicity threshold increased from 2.5 to 5 mg/mL after lysozyme coupling.
- Effective inhibition time against Streptococcus mutans was extended from 12 to 36 hours.

## Abstract

To develop a safe,
efficient, water-soluble, and targeted antibacterial
substance for medical applications, we synthesized carbon dots using
citric acid and urea as precursors by a solvothermal method. We then
coupled the carbon dots and lysozyme by using a simple 1-ethyl-3-(3′-dimethylaminopropyl)
carbodiimide-N–hydroxysuccinimide (EDC-NHS)
coupling method. After coupling, the carbon dots exhibited improved
water dispersibility with particle sizes ranging from 12 to 20 nm.
Notably, the highest carbon dot concentration associated with cytotoxicity
increased from 2.5 to 5 mg/mL when coupled with lysozyme, implying
that coupling could enhance the biocompatibility of carbon nanodots.
Furthermore, coupled carbon dots extended the effective inhibition
time against Streptococcus mutans from
12 to 36 h, compared to carbon dots alone. The improved biocompatibility
and prolonged effective antibacterial duration highlight the potential
of lysozyme-coupled carbon dots as a safe, efficient, and water-soluble
antibacterial agent for a variety of oral healthcare and medical applications.