Motor-based Microprobe For Motion Detection Of DNA

Biosensors are integrated devices combine high selective bio-recognition reactions with sensitive and convenient transducers. Compared with other biometric technologies, biosensor is cheaper, simpler and more convenient. And these biosensors have been widely used in a variety of biological target molecule detection. However, their applications are facing great challenges because most of them require long assay time, multiple washing and separation steps. Synthetic micro/nanomotors due to the simple preparation, controllable structure, available in volume production and its autonomous motion performance, have developed into an emerging hotspot and have been widely used in drug delivery, biosensing, targeted therapy and other fields. Motor-based detection protocol mostly relies on a sandwich identification assay. It is complex and costly since nano or micro particles are needed to label probes for identifying detection signal. To solve these problems, the research of this work is as follows:A motor-based microprobe is proposed using a tubular microengine powered by bio-assembled enzyme as catalyst and exploited for one-step and wash free detection of DNA through motion readout. The microprobe is fabricated by assembling of a catalase layer on the inner surface of poly(3,4-ethylenedioxythiophene)/Au (PEDOT/Au) microtube through DNA conjugate which is responsible for the biocatalytic bubble propulsion. The sensing concept of the microprobe is relied on the target-induced release of catalase through the DNA replace hybridization, which decreases the amount of enzyme assembled on microtube, and thus slows down the movement of the microprobe. Therefore, the motion speed is negatively correlated with the target concentration. At the optimal conditions, the microprobe can conveniently distinguish the concentration of specific DNA strands in a range of 0.5～10 μM without any washing and separation step. This microprobe can be easily prepared in batch with good reproducibility and stability. Its motion speed can be conveniently visualized by optical microscope. The proposed motor-based microprobe and its dynamic sensing method provide a novel approach for the development of intelligent microprobe and show considerable promise for diverse clinical and diagnostic applications.