Detection of ricin by using gold nanoclusters functionalized with chicken egg white proteins as sensing probes

• Published in: Biosensors & bioelectronics Vol. 92; pp. 410 - 416
• Main Authors: Selvaprakash, Karuppuchamy, Chen, Yu-Chie
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 15.06.2017
• Subjects: Animals; Biosensing Techniques - methods; Chemical Warfare Agents - analysis; Chickens; Egg Proteins - chemistry; Galactose - chemistry; Galactose, chicken egg white; Gold - chemistry; Limit of Detection; Nanostructures - chemistry; Nanostructures - ultrastructure; Ovalbumin - chemistry; Ovalbumin, gold nanoclusters; Oxidation-Reduction; Ricin; Ricin - analysis; Spectrometry, Fluorescence - methods; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - methods; Ricin; Galactose, chicken egg white; Ovalbumin, gold nanoclusters
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2016.10.086

Ricin produced from the castor oil plant, Ricinus communis, is a well-known toxin. The toxin comprises A and B chains. Ricin A chain can cause toxicity by inhibiting protein synthesis, and ricin B can bind to the galactose ligand on the cell membrane of host cells. Inhalation or ingestion of ricin may even lead to death. Therefore, rapid and convenient sensing methods for detecting ricin in suspicious samples must be developed. In this study, we generated protein encapsulated gold nanoclusters (AuNCs@ew) with bright photoluminescence by using chicken egg white proteins as starting materials to react with aqueous tetrachloroaurate. The generated nanoclusters, which were mainly composed of chicken ovalbumin-encapsulated AuNCs, can recognize ricin B because of the presence of Galβ(1→4)GlcNAc ligands on chicken ovalbumin. The generated conjugates of AuNCs@ew and ricin B were heavy and readily settled down under centrifugation (13,000rpm, 60min). Thus, bright spots resulting from the conjugates at the bottom of the sample vials were easily visualized by the naked eye under ultraviolet light illumination. The limit of detection (LOD) was ~4.6µM. The LOD was reduced to ~400nM when fluorescence spectroscopy was used as the detection tool, while the LOD can be further improved to ~7.8nM when using matrix-assisted laser desorption/ionization mass spectrometry as the detection method. We also demonstrated the feasibility of using the proposed approach to selectively detect ricin B chain in complex samples. [Display omitted] •A new sensing nanoprobe for ricin is discovered.•Chicken egg white is used as the reducing agents for generating nanoprobes.•The nanoprobes have red fluorescence and can specifically target ricin B chain.•The proposed method can be used to selectively detect ricin B from complex samples.•The limit of detection of ricin was as low as ~8 nM.