Aptamer-Modified Porous Anodized Aluminum Substrate for Rapid and Ultrasensitive Detection of Tetracycline via Surface Enhanced Raman Spectroscopy Couple with Electric Field Enrichment

Tetracycline (TC) has broad-spectrum antimicrobial activity and is low cost and widely used in animal disease treatment drugs and feed additives. However, the misuse of tetracycline causes serious damage to ecosystems and poses a major threat to human health. Therefore, the development of rapid and ultrasensitive TC detection methods is of great significance for the effective monitoring and prevention of TC pollution. Here, a surface enhanced Raman spectroscopy (SERS) sensor combined with electric field enrichment technology was developed for rapidly quantitative testing of TC. The SERS sensor was constructed by introducing Ag nanoparticles (AgNPs) and a Raman probe (4-aminothiophenol, 4-ATP) on the porous anodized aluminum (PAA) membrane through hybridization of aptamer-2 (Apt-2) with aptamer-1 (Apt-1). In the presence of TC, the SERS tags (4-ATP/AgNPs/Apt-2) dissociate from this sensing platform, attributed to the stronger specific binding of TC to Apt-1, leading to a significant decrease in the Raman signal, which enables indirect quantitative analysis of TC. Based on the ion current property of the composite PAA membrane and the high activity and specificity of the SERS substrate, TC can be rapidly enriched in 1 min by electric field enrichment technology and identified by potable Raman spectrometer in 3 min. The improved SERS sensor allows for a real-time response to 1 fg/mL–1 ng/mL TC, and the limit of detection (LOD) is 1 fg/mL. More importantly, the SERS sensor can be used to detect TC in real food samples (such as milk and shrimp) and has excellent performance. The sensing strategy is very promising for mitigating food security risk.