A High-Density Nanoporous SERS Substrate Prepared by Facile One-Step Anodization for P-Hydroxybenzoic Acid Detection

Area of Science:

• Materials Science
• Analytical Chemistry
• Nanotechnology

Background:

• Surface-enhanced Raman scattering (SERS) is a sensitive analytical technique.
• Conventional SERS substrates face challenges in fabrication, cost, and processing time.
• Developing efficient and cost-effective SERS substrates is crucial for food safety applications.

Purpose of the Study:

• To develop a novel, high-density porous anodic aluminum oxide (AAO) substrate for enhanced SERS detection of food preservatives.
• To optimize the fabrication process for improved efficiency and reduced cost.
• To evaluate the performance of the developed AAO substrate for detecting p-hydroxybenzoic acid.

Main Methods:

• Fabrication of a high-density porous AAO substrate using a one-step anodization process at 25 °C and a lower anodization voltage (20 V).
• Incorporation of a pore-widening step to increase SERS hotspots.
• Characterization of the AAO substrate structure and its effect on SERS signal intensity.
• Detection of p-hydroxybenzoic acid using the developed AAO substrate and calculation of analytical enhancement factors.

Main Results:

• The one-step anodization process at 25 °C significantly reduced fabrication time and improved efficiency.
• Lowering the anodization voltage to 20 V and employing pore widening resulted in a high-density porous structure with enhanced SERS signal intensity.
• Analytical enhancement factors ranged from 1.18 × 10^5 to 1.44 × 10^7 for p-hydroxybenzoic acid.
• A detection limit of 100 ppb for p-hydroxybenzoic acid was achieved, well below the regulatory limit.

Conclusions:

• The developed high-density porous AAO substrate offers a promising, cost-effective, and efficient alternative for SERS-based food safety analysis.
• The optimized fabrication method (one-step anodization with pore widening) enhances SERS performance.
• This approach significantly improves the detection limits for food preservatives, aiding in regulatory compliance.