DNA aptamer selection and detection of marine biotoxin 20 Methyl Spirolide G.

This study reports the selection of DNA aptamer for the detection of 20 Methyl Spirolide G (SPXG). After 10
rounds of selection, the enriched pool of aptamers specific to SPXG was cloned, sequenced and clustered into
seven families based on similarity. Three sequences SPX1, SPX2 and SPX7, each belonging to different clades
were further evaluated for their binding affinity. Surface plasmon resonance studies determined the highest affinity
KD of 0.0345x10-8 M for aptamer SPX7. A label-free microscale thermophoresis-based aptasensing using
SPX7 with highest affinity, indicated a linear detection range from 1.9 to 125000 pg/mL (LOD = 0.39 pg/mL;
LOQ = 1.17 pg/mL). Spiking studies in simulated contaminated samples of mussel and scallop indicated recoveries
in the range of 86 to 108%. Results of this study indicate the successful development of an aptamer for
detection of SPXG at picogram levels. It also opens up avenues to develop other sensing platforms for detection of
SPXG using the reported aptamer.