An Attempt to Develop an Aptamer Lateral-Flow Assay (ALFA) for Easy, Rapid, and Sensitive Detection of Lethal Mushroom Toxin α-amanitin

Amatoxins contribute to the majority of mushroom poisoning, most prominently, α-amanitin. Since mushroom is a common foodstuff worldwide, an easy, rapid, sensitive test for α-amanitin is needed. Several detection methods for α-amanitin have been developed, including HPLC, LC-MS, and ELISA, and LFIA. Aptamers have several advantages compared to antibodies: easy development via SELEX, longer shelf life, and higher temperature- and pH-tolerance. Aptamer Lateral Flow Assay (ALFA) is a similar technology compared to LFIA but incorporates aptamers as target-recognizing agents. This study attempted to develop an ALFA test strip for α-amanitin using a previously-developed aptamer, however failure of generating a colorimetric readout at the test line is persisted throughout all experiments, even though the concept is fully-proved and the control line functions normally. The failure is attributed to the small size of the molecule, leading to immobilization difficulties on the nitrocellulose membrane to form the test line, and the hindering of effective “surround” mechanism of aptamer-target binding (instead of “adhere”, when the target molecule is large, e.g. a protein). It is concluded that ALFAs for small-molecules whose aptamer-target interaction has not yet been studied and modelled in detail remains a challenge, despite ALFAs’ large potential.