Preparation of self-propelled Cu-Pt micromotors and their application in miRNA monitoring

Self-propelled catalytic micromotors offer considerable promise in terms of many applications. Catalytic micromotors are strongly influenced by the presence and concentration of specific ions and chemicals in the environment, making them useful as sensors and actuators. In this work, copper (Cu)-platinum (Pt) micromotors were fabricated by using the magnetron sputtering method for the first time in the literature and their applications based on the detection of miRNA-21 were evaluated. We analyzed the dependence of the mobility of Cu-Pt micromotors using different concentrations of hydrogen peroxide (H2O2) . The presence of surfactants in the environment is also important for the movement of the micromotors. Thus, we studied the effect of three different surfactants: anionic as sodium dodecyl sulfate (SDS), cationic as cetyltrimethylammonium bromide (CTAB), and nonionic as Triton X-100. Cu-Pt micromotor motion was observed even at very low concentrations of surfactant (0.01%) and hydrogen peroxide (0.25%). miRNAs have been regarded as biomarker candidates in early diagnosis. Our sensing strategy relied on dye-labeled single-stranded DNA immobilization onto Cu-Pt micromotors that recognize the target miRNA-21. The changes in the fluorescence intensity as well as the changes in the speed of micromotors were examined before and after hybridization.