www.afm-journal.de © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 2000112 (1 of 13) FULL PAPER Microrobots Derived from Variety Plant Pollen Grains for Efficient Environmental Clean Up and as an Anti-Cancer Drug Carrier Tijana Maric, Muhammad Zafir Mohamad Nasir, Nur Farhanah Rosli, Maja Budanovic´, Richard D. Webster, Nam-Joon Cho, and Martin Pumera* The production of large quantities of micromachines and microrobots is limited by fabrication methods and the use of synthetic templates. Pollen is one of the most stable structures in the world, capable of surviving harsh treatment and for millions of years. Pollen grains are available in large variety of shapes and sizes. The use of a wide variety of naturally abundant, nontoxic pollen grains for the efficient fabrication of platinum-pollen (Pt-pollen) hybrid microrobots capable of fast propulsion for environmental and biomedical applications is demonstrated. Nine different pollen grains are selected and modified (dandelion, pine, lotus, sunflower, poppy, camellia, lycopodium, cattail, and galla) to demonstrate the robustness of different types of pollen grains for potential applications in environmental remediation. The efficient mobility rendered by the fabricated microrobots enhances their performance in the removal of heavy metals in aqueous medium. Furthermore, they can be used as doxorubicin carriers. DOI: 10.1002/adfm.202000112 T. Maric, Dr. M. Z. M. Nasir, N. F. Rosli, Dr. M. Budanovic, Prof. R. D. Webster Division of Chemistry & Biological Chemistry School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371, Singapore Prof. N.-J. Cho School of Materials Science and Engineering Nanyang Technological University Singapore 637459, Singapore Prof. M. Pumera Center for Advanced Functional Nanorobots Department of Inorganic Chemistry Faculty of Chemical Technology University of Chemistry and Technology Prague Technická 5, Prague 6 166 28, Czech Republic E-mail: martin.pumera@vscht.cz Prof. M. Pumera Department of Chemical and Biomolecular Engineering Yonsei University 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea Prof. M. Pumera Department of Medical Research China Medical University Hospital China Medical University No. 91 Hsueh-Shih Road, Taichung 404, Taiwan Prof. M. Pumera Future Energy and Innovation Laboratory Central European Institute of Technology Brno University of Technology Purkyn ˇ ova 656/123, Brno CZ-616 00, Czech Republic self-propelling miniaturized devices are able to drive by the following mecha- nisms: self-electrophoresis, bubbles propulsion, self-diffusion phoresis, and Marangoni effect. [8–10] Small size and fast velocities of microrobots have been favorable properties serving as highly effi- cient platforms for water clean-up in the removal of heavy metals, [11,12] oils, [13,14] dyes, [15] chemical warfare agents, [16] phe- nolic pollutants, [17] pollutants degrada- tion, [1,18] and pathogens. [19] Recent efforts have also demonstrated wide range of biomedical application of microrobots as drug carriers, [20] cargo delivery, [21,22] nano- surgery, [23] and cancer therapy. [24–26] Previously, pollen grains have gained increasing attention due to their environ- mentally friendly properties, structural stability, biocompatibility, and monodispersity. [27–34] The exine (outer layer) is composed of a biologically and chemically resistant crosslinked biopolymer called sporopollenin, which is considered the diamond of biopolymers and exhibits remark- able mechanical stability even compared to many carbon types and synthetic polymers from which micromotors are typically fabricated. [27,28,35] In contrast, intine (inner layer) is made up of pectin, cellulose, proteins, and polysaccharides. Additionally, the hollow internal shells of pollen grains make them suitable 1. Introduction The main goal of nanotechnology is successful replacement of macroscopic vehicles with miniaturized devices—micro/ nanorobots that can perform similar or improved varied functions in environmental science and biomedical applica- tions. [1,2] Self-propelling autonomous nano/microrobots have garnered significant interest not only in nanotechnology but in other spectra of science also, such as medicine. [3–7] These The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.202000112. Adv. Funct. Mater. 2020, 2000112