Most of the protein-detection tests used in medical diagnostics—ELISA tests—require animal-derived antibodies, which are expensive and tend to be unstable during storage. Researchers from CEA-Leti and CEA-IRIG recently developed a new testing technology that can detect and count biomarkers without using antibodies. They cleverly combined aptamer testing with LAMP, a 20-year-old nucleic acid amplification technique similar to PCR amplification. LAMP augments the signal exponentially to help deliver a diagnosis faster and more cost effectively than conventional ELISA tests. 

Proof-of-concept testing was completed on thrombin, a key protein in the blood coagulation cascade that is also relevant for medical diagnostic applications. Aptamers are oligonucleotides* capable of binding to biomarkers like peptides or proteins and, in some cases, to DNA, as selectively as antibodies. Here, LAMP is used to amplify the aptamers so that they can be detected and quantified. The more target protein there is in the sample, the more aptamer there is, which means that the technique not only tells whether or not the biomarker is present, but also how much of it there is. Plus, with LAMP amplification, the signal is increased exponentially so that even very tiny amounts of the target protein can be picked up. In this research, the technology was able to detect quantities of around a nanomolar—just tens of micrograms per liter.

The new technology offers potential in the field of medical diagnostics, especially for cardiovascular issues where time is of the essence. Ultimately it could even be integrated into a portable medical device capable of providing an extremely accurate diagnosis in under an hour, ideal for emergency situations. It is currently being tested on blood samples in partnership with French national blood bank EFS and Saint-Etienne University Medical Center.

*Short fragments of nucleic acid chains (or short fragments of DNA)