Fluorometric sensing of pH values using green-emitting black phosphorus quantum dots

Area of Science:

• Materials Science
• Analytical Chemistry
• Nanotechnology

Background:

• Developing novel fluorescent sensors for accurate pH monitoring is crucial in various scientific fields.
• Black phosphorus quantum dots (BPQDs) are emerging nanomaterials with unique optical properties.
• Existing pH sensing methods may have limitations in sensitivity, stability, or applicability to biological samples.

Purpose of the Study:

• To develop a "turn-on" fluorometric sensor for pH detection using black phosphorus quantum dots (BPQDs).
• To synthesize and characterize water-stable BPQDs for reliable sensing applications.
• To evaluate the performance of BPQD-based sensor in biological samples like human urine and serum.

Main Methods:

• Synthesis of BPQDs via a liquid exfoliation method.
• Characterization using TEM, FT-IR, XPS, and absorption/fluorescence spectroscopy.
• Fluorometric analysis of BPQD response to varying pH levels.

Main Results:

• Synthesized BPQDs exhibit bright green fluorescence (excitation/emission 420/515 nm) and uniform particle size (5.2 nm).
• Fluorescence intensity of BPQDs is modulated by protonation/deprotonation of surface hydroxyl groups.
• A linear response was observed in the pH range of 1.0-9.0, with a "turn-on" mechanism below pH 4.0.
• Successful application of the sensor for pH determination in human urine and serum samples.

Conclusions:

• The developed BPQD-based sensor provides a sensitive and reliable "turn-on" method for pH detection.
• The sensor demonstrates excellent performance and applicability in complex biological matrices.
• BPQDs show significant potential as fluorescent probes for pH monitoring in biomedical and environmental applications.