Towards a Biocompatible Fuel to Improve Micro/Nanomachine Functionality

The process of finding a biocompatible fuel or a mechanism that allows current micro/nano machines navigate in different regions of the human body is still in its infancy. Tubular polyaniline (PANI)/Zn microrockets are shown to display effective autonomous motion in extreme acidic environments without any additional chemical fuel. The continuous thrust of hydrogen bubbles generated by the spontaneous redox reaction occurring at the inner Zn surface reflects the effective propulsion in acidic media. The propulsion characteristics of these microrockets were tested in different acidic media and in human serum. The observed ultrafast propulsion (as high as 100 body lengths/s) is a complementary functionality to their current guided movement and directed cargo transport capabilities. The speed-pH dependence of these PANI/Zn microrockets holds promise for sensitive pH measurements in extreme acidic environments. The goal of these efforts will not only obviate the hydrogen peroxide fuel requirement to catalytically propelled current microrockets but also allow advancement from current initial proof-of-concept studies into practical in vitro and in vivo biomedical applications for further evaluation.