Primary Amine Functionalized Carbon Dots for Dead and Alive Bacterial Imaging

Area of Science:

• Nanotechnology
• Biotechnology
• Materials Science

Background:

• Small molecular dyes for bacterial imaging suffer from toxicity and photobleaching.
• Carbon dots present a low-cost, low-toxicity alternative with anti-photobleaching properties.
• Enhancing carbon dot quantum yield and understanding bacterial imaging mechanisms remain challenges.

Purpose of the Study:

• To develop primary amine functionalized carbon dots for effective bacterial imaging.
• To improve quantum yield and photostability of carbon dots for bio-imaging applications.
• To investigate the mechanism of carbon dots in imaging both live and dead bacterial cells.

Main Methods:

• Preparation and characterization of four types of carbon quantum dots.
• Utilizing spermine as a precursor to enhance quantum yield and fluorescence stability.
• Surface modification with ethylenediamine for improved bacterial cell wall penetration.
• Detailed investigation of physical structure and chemical groups, particularly primary amine functionalities.

Main Results:

• Spermine-derived carbon dots exhibited a high quantum yield (66.46%) and excellent photobleaching resistance (70% fluorescence maintained after 3-h irradiation).
• Ethylenediamine modification enabled effective staining of both live and dead bacterial cells.
• Primary amine groups on spermine-carbon quantum dots were identified as crucial for visible live bacterial cell staining.

Conclusions:

• Primary amine functionalized carbon dots are promising for bacterial imaging, addressing limitations of traditional dyes.
• Spermine-based carbon dots offer superior quantum yield and photostability.
• The developed carbon dots provide an efficient and eco-friendly platform for bacterial imaging, with potential for further applications.