Simple homogeneous electrochemical target-responsive aptasensor based on aptamer bio-gated and porous carbon nanocontainer derived from ZIF-8.

A simple homogeneous electrochemical aptasensor was designed by using target-responsive substrate releasing from aptamer-gated zeolitic imidazolate framework-8 (ZIF-8)-derived porous carbon nanocontainer. The nanocontainer (Z-700) was prepared by calcination of ZIF-8 at 700 °C. Z-700 had great biocompatibility, high surface areas and pore volume, especially the graphene-like π-rich structure, which was beneficial for adsorbing aptamer easily. The electroactive dyes methylene blue (MB) was then trapped in the pores of Z-700 and easily capped with aptamer as gatekeeper based on π-stacking interaction. Upon addition of target protein thrombin (Thb), the Thb could specifically recognize and combine with its aptamer to form complex. Thereafter, the aptamer bio-gate opened and the MB released from the pores, which could be detected on the screen-printed electrode. Under the optimized conditions, the proposed Thb aptasensor showed a wide detection range from 1 fM to 1 nM with a low detection limit of 0.57 fM. The strategy by using ZIF-8-derived porous carbon and aptamer bio-gate provides a promising scheme for developing simple, rapid, reliable and ultrasensitive bioassays, which has a great potential as a powerful tool in disease diagnosis and biomedicine.