Highly sensitive and rapid visual detection of ricin using unmodified gold nanoparticle probes

Abstract

Herein, a sensitive and selective colorimetric biosensor for the detection of ricin was demonstrated with a 40-mer ricin-binding aptamer (RBA) as recognition element and unmodified gold nanoparticles (AuNPs) as probe. The sensitivity of the assay was greatly improved after optimizing several key parameters such as the amount of aptamer adsorbed on AuNPs, the concentration of NaCl, and the reaction time after adding NaCl. The linear range for the current analytical system was from 0.31 nM to 11.55 nM. The corresponding limit of detection (LOD) was 0.31 nM. Some different proteins such as thrombin (Th), horseradish peroxidase (HRP), lysozyme (Lys), glucose oxidase (GOx), and bovine albumin (BSA) showed no or just a little interference in the determination of ricin. This colorimetric aptasensor is superior to the other conventional methods owing to its simplicity, low cost, high sensitivity and detection with the naked eye, which can be used in real samples.