A new coccolith modified electrode-based biosensor using a cognate pair of aptamers with sandwich-type binding.

In this study, we report a cognate pair of the aptamer-based sandwich-type electrochemical biosensor for type 2 diabetes biomarker (Vaspin) using coccolith modified electrodeposited on the screen-printed gold electrode (CME-SPGE). The coccolith derived from E. huxleyi used in this study were known to be highly-structured microparticles with many nano-sized pores. The CME-SPGE was successfully fabricated by drop-casting coccoliths, followed by Au sputtering and electrodeposition of Au. On this CME-SPGE electrode, the sandwich-type electrochemical aptasensor was fabricated by using a cognate pair of aptamers. The morphological, electrochemical characteristics and the performances of both the CME-SPGE and the completely fabricated sandwich-type aptasensor were investigated by SEM, EDAX, cyclic voltammetry, and chronoamperometry. Due to the synergic effect of a cognate pair of aptamers on CME-SPGE, this newly developed sandwich-type electrochemical biosensor for Vaspin showed high specificity, and good sensitivity with a limit of detection (LOD) of 298 pM, along with more widen the linear range. To the best of our knowledge, this is the first report about the use of a coccolith modified electrode with a cognate pair aptamer resulting in sandwich-type binding in an electrochemical biosensor. With the advantages of using highly-structured biomineral microparticles and a cognate pair of aptamers, this new study may pave the innovative way to design a novel sandwich-type electrochemical aptasensor platform.