pH-Sensitive Silver-Containing Carbon Dots Based on Folic Acid.

Area of Science:

• Materials Science
• Nanotechnology
• Analytical Chemistry

Background:

• Carbon dots (CDs) are versatile nanomaterials with unique optical properties.
• Folic acid is a biocompatible precursor for synthesizing functionalized nanomaterials.
• Silver incorporation can modulate the photoluminescence of carbon dots.

Purpose of the Study:

• To synthesize silver-containing carbon dots (Ag-CDs) using folic acid.
• To investigate the pH-dependent fluorescence mechanism of Ag-CDs.
• To explore the potential of Ag-CDs as fluorescent sensors.

Main Methods:

• Synthesis of Ag-CDs from folic acid.
• Characterization using fluorescence spectroscopy (emission and excitation spectra).
• Analysis of electronic absorption origins.
• Investigation of pH effects using UV-Vis absorption and X-ray Photoelectron Spectroscopy (XPS).

Main Results:

• Ag-CDs exhibited distinct fluorescence species with different excitation and emission characteristics.
• The electronic absorption origins of fluorescent species were assigned.
• A pH-regulating fluorescence mechanism was proposed, involving a mixing coordination structure (Ag(CDs-NH2)OH) at pH ~12.
• A strong fluorescence emitter was observed at extremely basic conditions (pH ~12).

Conclusions:

• The synthesized Ag-CDs possess tunable fluorescence properties influenced by pH.
• The study elucidated the pH-dependent fluorescence mechanism of Ag-CDs.
• Ag-CDs show promise for development into fluorescent sensors, especially for applications in highly alkaline media.