Biohybrid microrobots combine flagellated chemotactic bacteria with a synthetic cargo for the propulsion and steering. They are extensively studied for delivery of sensitive materials such as peptides, plasmid DNA proteins and other therapeutic agents to mammalian cells. In order to achieve maximum functionality, these two components have to be incorporated efficiently. Besides cargo integration, controlled release of the cargo is the key factor determining the efficiency for delivery applications. Controlling on-site release and active delivery of the cargo improves the bioavailability of the administration. However, very few numbers of studies so far reported demonstrating the release of cargo from a biohybrid system with respect to external stimuli. Therefore, we propose a method to spatially and temporally control the integration and the release of cargo by using visible light as the trigger. Upon red light illumination, a micro size polystyrene particle as cargo is integrated into the body of a bacteria cell (<i>E.coli</i>) and transported to the target site. Upon far-red light illumination, the cargo is release at the target site. For such, we exploit light dependent unique photoisomerization ability of the proteins phytochrome B (PhyB) with the phytochrome interaction factor 6 (PIF6). Upon red light treatment (650 nm) PhyB protein dimerizes with PIF6 and this interaction is reversed under far-red light. Our experimental results demonstrate a dynamic effective cargo integration and cargo release for the first time by using non-benign visible light as the stimuli as a proof-of-concept. This study paves the way towards improving the control of biosystems with a transforming impact in bioengineering, targeted drug delivery, and lab-on-a-chip devices.

Red/far-red light controlled bacteria-driven microrobots for cargo delivery and release

2019 Fall National Meeting

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