Fluorescent carbon dots derived from urine and their application for bio-imaging

Area of Science:

• Materials Science
• Biotechnology
• Nanotechnology

Background:

• Developing novel fluorescent probes for bio-imaging is crucial for advancing biological research and diagnostics.
• Low-cost, biocompatible, and water-soluble fluorescent materials are highly sought after for in vivo and in vitro applications.

Purpose of the Study:

• To synthesize water-soluble fluorescent carbon dots (C-dots) from urine, a low-value metabolite, via a simple and economical one-step method.
• To characterize the synthesized C-dots and evaluate their potential as fluorescent probes for bio-imaging.

Main Methods:

• Urine-derived carbon dots (UCDs) were prepared using Sephadex filtration, and hydrothermally treated urine C-dots (HUCDs) were synthesized via hydrothermal reaction.
• Characterization involved Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), and Fourier-transform Infrared (FTIR) spectroscopy.
• In vitro and in vivo bio-imaging were performed on Hela cells, Caenorhabditis elegans, onion epidermal cells, and bean sprouts. Cytotoxicity was assessed using normal rat kidney (NKR) cells.

Main Results:

• UCDs and HUCDs were successfully synthesized with average sizes of 2.5 nm and 5.5 nm, respectively.
• HUCDs exhibited a significantly higher fluorescence quantum yield (17.8%) compared to UCDs (4.8%).
• Spectroscopic analyses confirmed the presence of carbon, oxygen, nitrogen, and functional groups like amino, hydroxyl, carboxylate, and carbonyl on the C-dots. The synthesized C-dots demonstrated good biocompatibility and low cytotoxicity.

Conclusions:

• Urine-derived carbon dots (UCDs and HUCDs) are water-soluble, fluorescent, and possess good biocompatibility.
• These C-dots show potential as safe and effective fluorescent probes for various bio-imaging applications.
• The simple and economical synthesis route makes these C-dots a promising alternative to conventional fluorescent probes.