Molybdenum Disulfide-Based Tubular Microengines: Toward Biomedical Applications

2D molybdenum disulfi de (MoS2) is herein explored as an advanced surface material in the fabrication of powerful tubular microengines. The new catalytic self-propelled open-tube bilayer microengines have been fabricated using a template electrodeposition and couple the unique properties of sp(2) hybridized MoS2 with highly reactive inner granular Pt catalytic structures. The MoS2 /metal microengines display extremely efficient bubble propulsion, reflecting the granular structure of the inner catalytic platinum or gold layers (compared to the smooth metal surfaces of common micromotors). The efficient movement of functionalized MoS2 micromotors can address challenges imposed by slow mass transport processes involved in various applications of MoS2. The delocalized electron network of the MoS2 outer layer facilitates pi-pi stacking interactions and endows the tubular microengines with a diverse array of capabilities. These are demonstrated here for efficient loading and release of the drug doxorubicin, and rapid and sensitive OFF-ON fluorescent detection of important nucleic acids (miRNA-21) and proteins (thrombin) using microengines modified with dye-labeled single-stranded DNA and aptamer, respectively. Such coupling of the attractive capabilities of 2D-MoS2 nanosheets with rapidly moving microengines provides an opportunity to develop multifunctional micromachines for diverse biomedical applications ranging from efficient drug delivery to the detection of important bioanalytes.