One Stone, Two Birds: pH- and Temperature-Sensitive Nitrogen-Doped Carbon Dots for Multiple Anticounterfeiting and...

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Carbon dots (CDs) are emerging fluorescent nanomaterials with significant potential in anticounterfeiting and bioimaging.
• Developing biocompatible and highly responsive fluorescent probes is crucial for advanced applications.

Purpose of the Study:

• To synthesize nitrogen-doped carbon dots (NCDs) using a straightforward thermal sintering method.
• To investigate the photoluminescent properties and environmental sensitivity of NCDs for potential applications.

Main Methods:

• Synthesis of NCDs via thermal sintering.
• Characterization of photoluminescence properties, including excitation-dependent emission and solvatochromism.
• Evaluation of NCDs' response to temperature and pH variations.
• Demonstration of NCDs in fluorescent inks for pattern printing.

Main Results:

• NCDs exhibited excellent biocompatibility and tunable fluorescence properties.
• A large red shift (∼130 nm) in emission was observed with excitation wavelengths from 355 to 550 nm.
• NCDs displayed distinct changes in emission intensity and peak position with temperature (223–323 K) and pH (1–13).
• Nontoxic NCDs were successfully used in water-soluble fluorescent inks to create a "horse" pattern.

Conclusions:

• NCDs are highly sensitive to excitation wavelength, temperature, and pH, making them versatile fluorescent materials.
• The observed properties indicate significant potential for NCDs in multicolor cell imaging and advanced anticounterfeiting technologies.