Phototactic Biohybrid Microrobot Using Peptide Nanotubes-Coated Microalgae for pH-Responsive Active Drug Delivery

Despite the recent wide investigation on active cancer drug delivery, there are still strong medical unmet needs for active tumor-environment responsive cancer drug delivery in terms of spatiotemporal control. Herein, a biohybrid system of pH-responsive peptide nanotubes (PNTs)-coated microalgae for active cancer drug delivery in response to the tumor-environment is developed. The amphiphilic PNTs are effectively used to encapsulate cancer drugs and coat the living microalgae of C. reinhardtii by electrostatic interactions. The drug-loaded PNTs-based biohybrid microalgae maintain agile movement with phototaxis behavior. After in vitro characterization and cytotoxicity assessment, it is shown that the biohybrid microalgae could be phototactically localized to the cancer cells and pH-responsively disassembled to release cancer drugs in a controlled manner. Finally, with the encapsulation of paclitaxel, the statistically significant suppression of tumor growth in xenograft tumor model animals is successfully demonstrated. Taken together, the feasibility of the multifunctional microrobotic platform for advanced cancer therapy is confirmed.