A reversible, colorimetric, pH-responsive indole-based hydrogel and its application in urea detection

Area of Science:

• Materials Science
• Analytical Chemistry
• Chemical Engineering

Background:

• Developing sensitive and selective sensors for environmental and biological analytes is crucial.
• Hydrogels offer versatile platforms for chemical sensing due to their tunable properties.
• Indole-based materials present unique electronic and structural characteristics for molecular interactions.

Purpose of the Study:

• To develop a novel pH-responsive indole-based hydrogel for the colorimetric detection of urea.
• To investigate the sensing mechanism involving cation-π interaction and hydrogen bonding.
• To evaluate the sensor's performance, including linear range, limit of detection, selectivity, and regenerability.

Main Methods:

• Fabrication of the pH-responsive indole-based (4-HINF) hydrogel using a sol-gel method.
• Utilizing the hydrogel as a platform for colorimetric urea detection in aqueous solutions.
• Characterizing the synergistic effects of cation-π interaction and hydrogen bonding in the sensing mechanism.
• Assessing the sensor's response linearity, limit of detection, selectivity, and regenerative ability.

Main Results:

• The 4-HINF hydrogel demonstrated effective colorimetric detection of urea.
• A linear response was observed in the concentration range of 0–10 mM.
• The limit of detection for urea was determined to be 10 μM.
• The sensor exhibited high selectivity to pH changes and good regenerative ability.

Conclusions:

• The developed indole-based hydrogel serves as a promising platform for sensitive and selective urea detection.
• The synergistic cation-π interaction and hydrogen bonding contribute to the sensor's efficacy.
• The sensor's properties ensure its potential for applications in complex environmental and biological systems.