A water-soluble boronic acid sensor for caffeic acid based on double sites recognition

Area of Science:

• Analytical Chemistry
• Chemical Sensing
• Fluorescence Spectroscopy

Background:

• Boronic acid compounds are versatile fluorescent sensors for various analytes.
• Selective detection of caffeic acid using boronic acid sensors remains a challenge.
• Existing sensors often lack specificity for caffeic acid over similar compounds like catechol.

Purpose of the Study:

• To develop a novel water-soluble boronic acid-based sensor (5c) for highly selective caffeic acid recognition.
• To investigate the sensing mechanism and performance of sensor 5c.
• To evaluate the sensor's applicability in real sample analysis.

Main Methods:

• Synthesis of a novel water-soluble boronic acid sensor (5c) with dual recognition sites.
• Fluorescence spectroscopy to monitor the interaction between sensor 5c and analytes.
• Inner filter effect (IFE) mechanism utilized for caffeic acid detection.
• Determination of binding constants and limit of detection (LOD).
• Application of the sensor for caffeic acid quantification in pharmaceutical tablets.

Main Results:

• Sensor 5c exhibited a significant fluorescence quenching (99.6%) upon addition of caffeic acid (2.3 × 10^-4 M) via IFE.
• The sensor demonstrated high selectivity for caffeic acid over carbohydrates and catechol derivatives.
• Fast response time at room temperature was observed.
• A high binding constant (9245.7 ± 348.3 M^-1) and low LOD (1.81 × 10^-6 M) were achieved.
• Successful determination of caffeic acid content in tablets with sufficient recovery rates.

Conclusions:

• Sensor 5c is a highly selective and sensitive fluorescent probe for caffeic acid detection.
• The inner filter effect plays a crucial role in the sensing mechanism.
• The developed sensor shows potential for practical applications in detecting biologically significant caffeic acid in real samples.