An electrochemical biosensor has been developed by researchers in Spain that is capable of detecting meat products contaminated by horse.
The disposable biosensor detects a tiny piece of DNA which has been found to be virtually unchanged in the more than 4500 mitochondrial genomes of horses sequenced to date, but is absent in other species of mammals.
The biosensor was created by researchers at the Complutense University of Madrid, who have reported on its development in the journal Analytical Chemistry.
Javier Gallego, a researcher in the Department of Genetics, says the biosensor will detect horse meat without any false positives.
It can deliver a result in only one hour and is capable of detecting as little as 0.5% of horse meat by weight in beef – the level set by European legislation.
Until now, the ways to detect these meat adulterations were based on immunological, spectroscopic or molecular biology techniques.
These methods were often not sufficiently selective to differentiate close animal species, due to the possibility of cross-reactions, or were not sufficiently reliable in processed products due to the breakdown of the proteins and DNA that occur, explains co-author Susana Campuzano, a researcher in the department of Analytical Chemistry at the university.
The multidisciplinary team found that better results were obtained in mitochondrial DNA fragments than in nuclear DNA because the former is more protected and better resistant to possible heat treatments.
These results are the result of collaboration between the Faculties of Chemistry and Biology at the university.
While Gallego’s team identified the specific fragment to be detected, designed the appropriate probe for it and contributed with his knowledge and experience in techniques of mitochondrial DNA extraction and preparation of mitochondrial lysates, the Department of Analytical Chemistry, led by Professor José Pingarrón, designed an adequate electrochemical biosensor capable of satisfying the requirements of sensitivity and selectivity necessary to comply with current legislation for the detection of this type of adulteration.
Most of the experimental work that led to this development was carried out by doctoral student Víctor Ruiz-Valdepeñas Montiel, and Master’s student María Luisa Gutiérrez.
“In addition to moving to the identification of other mammalian DNAs, this methodology could be applied for both the detection of adulterations involving other animal meats and for screening purposes to identify all animal species present in a meat,” says Pingarrón.
The study team described the development as an extremely interesting tool for beef-meat screening.
Víctor Ruiz-Valdepeñas Montiel, María L. Gutiérrez, Rebeca M. Torrente-Rodríguez, Eloy Povedano, Eva Vargas, Á. Julio Reviejo, Rosario Linacero, Francisco J. Gallego, Susana Campuzano, José M. Pingarrón. Disposable Amperometric Polymerase Chain Reaction-Free Biosensor for Direct Detection of Adulteration with Horsemeat in Raw Lysates Targeting Mitochondrial DNA. Analytical Chemistry, 2017; 89 (17): 9474 DOI: 10.1021/acs.analchem.7b02412
The abstract can be read here.