pH-Responsive Motors and their Interaction with RAW 264.7 Macrophages

Abstract

Nano/micromotors are self-propelled particles that use external stimuli to gain locomotion outperforming Brownian motion. Here, three different polymers are employed that are conjugated to silica particles through a pH-labile linker. At slightly acidic pH, the linkers hydrolyze and release the polymeric chains, resulting in enhanced locomotion. The motors show a maximum velocity of ≈3 µm s−1 in cell media when poly(ethylene glycol) methyl ether methacrylate is asymmetrically distributed on the surface of the particles. Further, the motor internalization by RAW 264.7 macrophages was compared between motors, which have the polymer conjugated via a pH-labile linker, and the irresponsive particles. Preliminary data indicate enhanced uptake, but further efforts are required to use responsive polymers to propel motors inside mammalian cells.