Detection of nitrite with a surface-enhanced Raman scattering sensor based on silver nanopyramid array

Area of Science:

• Environmental Science
• Analytical Chemistry
• Materials Science

Background:

• Nutrient pollution from fertilizers and waste introduces nitrite into aquatic systems, posing environmental and health risks.
• Accurate and sensitive detection of nitrite is crucial for water quality monitoring and environmental protection.

Purpose of the Study:

• To develop a highly sensitive and selective surface-enhanced Raman scattering (SERS) sensor for nitrite detection.
• To utilize the synergistic plasmonic coupling between gold nanostars and silver nanopyramids for signal amplification.

Main Methods:

• Fabrication of a SERS sensor by coupling plasmonic gold nanostars with silver nanopyramid arrays.
• Utilizing the reaction between nitrite, 1-naphthylamine, and 4-aminothiophenol to form an azo group, creating SERS "hot spots".
• Employing finite-difference time-domain (FDTD) simulation to analyze SERS enhancement factors.

Main Results:

• Achieved a limit of detection of 0.6 pg/mL for nitrite in water.
• Demonstrated selective nitrite detection in real-world river water samples.
• Observed a remarkable SERS enhancement factor of 4 × 10^10 at the "hot spots".

Conclusions:

• The developed SERS sensor offers a sensitive, selective, and cost-effective method for nitrite detection.
• This approach eliminates the need for expensive molecular probes or Raman reporters.
• The sensor shows significant advantages over existing colorimetric, electrochemical, and fluorescent methods for small molecule detection.