RF plasma-enhanced conducting Polymer/WO based self-propelled micromotors for miRNA detection.

Functionalized micro/nanomotors having immobilized biological molecules provide excellent and powerful tools for the detection of target molecules. Based on surface modifications and mobilities of micromotors, we report herein a new experimental design of high-speed, self-propelled and plasma modified micromotors for biomedical applications. Within this scope, in the first step, poly (3,4-ethylenedioxythiophene) (PEDOT) was in-situ synthesized onto WO (tungsten trioxide) wires by using radio frequency (RF) rotating plasma reactor. Then, WO/PEDOT-Platinum (Pt) hybrid micromotors were fabricated by using magnetron sputtering technique. The detection of miRNA-21 was performed using both single-stranded DNA (ssDNA) (probe DNA) immobilized WO-Pt and WO/PEDOT-Pt micromotors. The fluorescence signals were determined after hybridization of probe DNA immobilized these novel WO-Pt and WO/PEDOT-Pt micromotors with different molar concentrations of the synthetic target (6-carboxyfluorescein dye (FAM)-labeled miRNA-21). The changes in the micromotor speeds after the hybridization process were also evaluated. WO/PEDOT-Pt micromotors presented better sensor properties compared to the WO-Pt micromotors. A good linearity for miRNA-21 concentration between 0.1 nM and 100 nM was obtained for these micromotors based on their fluorescence intensities. The detection limit was found as 0.028 nM for WO/PEDOT-Pt micromotors (n = 3). Thus, sensor and motor characteristics of the WO-Pt micromotors were improved by RF plasma enhanced PEDOT coatings. The new catalytic WO based micromotors demonstrated here had great potential for the development of sensitive and simple sensing platforms for detection of miRNA-21.