Aptamers are short, single stranded sections of DNA or RNA that can selectively bind to a protein or similar biochemical molecule. They are, theoretically, an ideal basis for species tests; unlike PCR, they could underpin a test for highly processed products that was also faster, cheaper, and more suited for point-of-use kits.
To date, there is no published porcine-specific aptamer that is specifically bound to a heat-stable protein. This study (purchase required) has taken some important steps along the way, but also highlights the challenges. The authors screened, characterised and validated aptamers bound to any pork protein through the SELEX process, combined with Next Generation Sequencing (NGS) and Liquid Chromatography Mass Spectrometry (LC-MS) analysis. The putative porcine-specific aptamers were selected after fourteen rounds of selection using centrifugal-ultrafiltration separation technique against five negative controls. The best candidate had a binding affinity with a dissociation constant of 27.61 ± 1.92 nM. However, the selected porcine-bound aptamers were not specific and could also bind to multiple proteins from negative samples. LC-MS analysis showed that the aptamers bound to troponin and tropomyosin subunits, and these proteins have potential as target markers for future authentication studies. The authors conclude that future research could develop aptamers with higher specificity towards porcine protein which could be used as a practical tool for food authentication in real meat-based food samples.
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