Dynamics of a bifunctional motor under crowded conditions

A simple and inexpensive fabrication of a polymer based bifunctional motor, containing catalytic palladium nanoparticles (Pd NPs) and luminescent zinc quinolate inorganic complex (Zn-QC), is reported. The motor displayed buoyancy driven self-propulsion in aqueous hydrogen peroxide (H<inf>2</inf>O<inf>2</inf>) solution, and could be easily tracked within liquid media using its luminescence under UV light. The propulsion speed and the luminescence of the motor were found to be correlated with the solution viscosity and local concentration of macromolecules within the medium. The bifunctional motor was further used to monitor bacterial concentration in solutions and was found to be an excellent probe for simultaneous characterization of spatio-temporal density and viscosity profiles of inhomogeneous solutions and particle assemblies. The motor fabricated is scalable and offers convenient platform for using self-powered catalytic motors in gleaning comprehensive insights into the rheology and density profiles of complex crowded systems, like the cytosol.