Dynamic Isolation and Unloading of Target Proteins by Aptamer-Modified Microtransporters

We describe here a new strategy for isolating target proteins from complex biological samples based on an aptamer-modified self-propelled microtube engine. For this purpose, a thiolated thrombin or a mixed thrombin-ATP aptamer (prehybridized with a thiolated short DNA) was coassembled with mercaptohexanol onto the gold surface of these microtube engines. The rapid movement of the aptamer-modified microtransporter resulted in highly selective and rapid capture of the target thrombin, with an effective discrimination against a large excess of nontarget proteins. Release of the captured thrombin can be triggered by the addition of ATP that can bind and displace the immobilized mixed thrombin ATP aptamer in 20 min. The rapid loading and unloading abilities demonstrated by these selective microtransporters are illustrated in complex matrixes such as human serum and plasma. The new motion-driven protein isolation platform represents a new approach in bioanalytical chemistry based on active transport of proteins and offers considerable promise for diverse diagnostic applications.