Sensitive and selective SERS probe for trivalent chromium detection using citrate attached gold nanoparticles

Area of Science:

• Analytical Chemistry
• Materials Science
• Environmental Science

Background:

• Trivalent chromium (Cr(3+)) is a toxic heavy metal pollutant.
• Sensitive and selective detection methods for Cr(3+) are crucial for environmental safety.
• Surface-enhanced Raman spectroscopy (SERS) offers high sensitivity for detecting trace analytes.

Purpose of the Study:

• To develop a novel SERS probe for sensitive and selective detection of Cr(3+).
• To investigate the mechanism behind the SERS signal enhancement for Cr(3+) detection.
• To evaluate the probe's stability and selectivity against other metal ions.

Main Methods:

• Citrate-capped gold nanoparticles (AuNPs) were synthesized.
• Tween 20 was introduced to stabilize the AuNPs, creating a Tween 20/citrate-AuNP probe.
• The probe's performance for Cr(3+) detection was evaluated using SERS in an aqueous medium (pH 6.0).
• AuNP aggregation induced by Cr(3+) chelation with citrate was studied.

Main Results:

• The Tween 20/citrate-AuNP probe detected Cr(3+) at a concentration as low as 50 × 10(-9) M.
• Tween 20 enhanced the probe's stability in high ionic strength conditions.
• Cr(3+) induced AuNP aggregation, creating hot spots for significant SERS signal enhancement via electromagnetic field effects.
• The probe exhibited a selectivity of 400-fold for Cr(3+) over other metal ions.

Conclusions:

• The developed Tween 20/citrate-AuNP probe is a sensitive and selective SERS platform for Cr(3+) detection.
• The probe's stability and enhanced SERS signal are attributed to Tween 20 and Cr(3+)-induced aggregation.
• This method holds promise for environmental monitoring of Cr(3+) contamination.