The development of artificial small-scale robotic swarms with nature-mimicking collective behaviors represents the frontier of research in robotics. While microrobot swarming under magnetic manipulation has been extensively explored, light-induced self-organization of micro- and nanorobots is still challenging. This study demonstrates the interaction-controlled, reconfigurable, reversible, and active self-assembly of TiO2/α-Fe2O3 microrobots, consisting of peanut-shaped α-Fe2O3 (hematite) microparticles synthesized by a hydrothermal method and covered with a thin layer of TiO2 by atomic layer deposition (ALD). Due to their photocatalytic and ferromagnetic properties, microrobots autonomously move in water under light irradiation, while a magnetic field precisely controls their direction. In the presence of H2O2 fuel, concentration gradients around the illuminated microrobots result in mutual attraction by phoretic interactions, inducing their spontaneous organization into self-propelled clusters. In the dark, clusters reversibly reconfigure into microchains where microrobots are aligned due to magnetic dipole-dipole interactions. Microrobots' active motion and photocatalytic properties were investigated for water remediation from pesticides, obtaining the rapid degradation of the extensively used, persistent, and hazardous herbicide 2,4-Dichlorophenoxyacetic acid (2,4D). This study potentially impacts the realization of future intelligent adaptive metamachines and the application of light-powered self-propelled micro- and nanomotors toward the degradation of persistent organic pollutants (POPs) or micro- and nanoplastics.

Advanced Nanorobots and Multiscale Robotics Laboratory Faculty of Electrical Engineering and Computer Science VSB Technical University of Ostrava 17 listopadu 2172 15 70800 Ostrava Czech Republic

Department of Chemical and Biomolecular Engineering Yonsei University Yonsei ro 50 Seodaemun gu 03722 Seoul Republic of Korea

Department of Medical Research China Medical University Hospital China Medical University Hsueh Shih Road 91 40402 Taichung Taiwan

Future Energy and Innovation Laboratory Central European Institute of Technology Brno University of Technology Purkyňova 123 61200 Brno Czech Republic

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Cazamine, S. et al. Self-Organization in Biological Systems (Princeton University Press, 2001).

Anderson C, Theraulaz G, Deneubourg JL. Self-assemblages in insect societies. Insectes Soc. 2002;49:99–110. doi: 10.1007/s00040-002-8286-y. DOI

Mlot NJ, Tovey CA, Hu DL. Fire ants self-assemble into waterproof rafts to survive floods. Proc. Natl. Acad. Sci. USA. 2011;108:7669–7673. doi: 10.1073/pnas.1016658108. PubMed DOI PMC

Liu D, et al. Bionic morphological design and interface-free fabrication of Halfmoon microrobots with enhanced motion performance. Chem. Eng. J. 2023;452:139464. doi: 10.1016/j.cej.2022.139464. DOI

Sun M, et al. Magnetic microswarm and fluoroscopy-guided platform for biofilm eradication in biliary stents. Adv. Mater. 2022;34:2201888. doi: 10.1002/adma.202201888. PubMed DOI

Xu Z, Xu Q. Collective behaviors of magnetic microparticle swarms: from dexterous tentacles to reconfigurable carpets. ACS Nano. 2022;16:13728–13739. doi: 10.1021/acsnano.2c05244. PubMed DOI

Wang B, et al. Spatiotemporally actuated hydrogel by magnetic swarm nanorobotics. ACS Nano. 2022;16:20985–21001. doi: 10.1021/acsnano.2c08626. PubMed DOI

Li M, et al. A diatom-based biohybrid microrobot with a high drug-loading capacity and pH-sensitive drug release for target therapy. Acta Biomater. 2022;154:443–453. doi: 10.1016/j.actbio.2022.10.019. PubMed DOI

Fonseca ADC, Kohler T, Ahmed D. Ultrasound-controlled swarmbots under physiological flow conditions. Adv. Mater. Interfaces. 2022;9:2200877. doi: 10.1002/admi.202200877. DOI

Huang T-Y, Gu H, Nelson BJ. Increasingly intelligent micromachines. Annu. Rev. Control. Robot. Auton. Syst. 2022;5:279–312. doi: 10.1146/annurev-control-042920-013322. DOI

Soto F, et al. Smart materials for microrobots. Chem. Rev. 2022;122:5365–5403. doi: 10.1021/acs.chemrev.0c00999. PubMed DOI

Urso M, Pumera M. Micro- and nanorobots meet DNA. Adv. Funct. Mater. 2022;32:2200711. doi: 10.1002/adfm.202200711. DOI

Huang H, et al. Large-scale self-assembly of MOFs colloidosomes for bubble-propelled micromotors and stirring-free environmental remediation. Angew. Chem. Int. Ed. 2022;61:e202211163. doi: 10.1002/anie.202211163. PubMed DOI

Wang L, et al. Contaminants-fueled laccase-powered Fe3O4@SiO2 nanomotors for synergistical degradation of multiple pollutants. Mater. Today Chem. 2022;26:101059. doi: 10.1016/j.mtchem.2022.101059. DOI

Gordón Pidal JM, Arruza L, Moreno-Guzmán M, López MÁ, Escarpa A. OFF-ON on-the-fly aptassay for rapid and accurate determination of procalcitonin in very low birth weight infants with sepsis suspicion. Sens. Actuators B Chem. 2023;378:133107. doi: 10.1016/j.snb.2022.133107. DOI

Gordón J, et al. On the move-sensitive fluorescent aptassay on board catalytic micromotors for the determination of interleukin-6 in ultra-low serum volumes for neonatal sepsis diagnostics. ACS Sens. 2022;7:3144–3152. doi: 10.1021/acssensors.2c01635. PubMed DOI PMC

Zhang F, et al. Nanoparticle-modified microrobots for in vivo antibiotic delivery to treat acute bacterial pneumonia. Nat. Mater. 2022;21:1324–1332. doi: 10.1038/s41563-022-01360-9. PubMed DOI PMC

Oral CM, et al. Radiopaque nanorobots as magnetically navigable contrast agents for localized in vivo imaging of the gastrointestinal tract. Adv. Healthc. Mater. 2023;12:2202682. doi: 10.1002/adhm.202202682. PubMed DOI

de la Asunción-Nadal V, et al. MoSBOTs: magnetically driven biotemplated MoS2-based microrobots for biomedical applications. Small. 2022;18:2203821. doi: 10.1002/smll.202203821. PubMed DOI

Yang W, Wang X, Wang Z, Liang W, Ge Z. Light-powered microrobots: recent progress and future challenges. Opt. Lasers Eng. 2023;161:107380. doi: 10.1016/j.optlaseng.2022.107380. DOI

Moran J, Posner J. Microswimmers with no moving parts. Phys. Today. 2019;72:44–50. doi: 10.1063/PT.3.4203. DOI

Dong R, Zhang Q, Gao W, Pei A, Ren B. Highly efficient light-driven TiO2-Au Janus micromotors. ACS Nano. 2016;10:839–844. doi: 10.1021/acsnano.5b05940. PubMed DOI

Xiao Z, et al. Synergistic speed enhancement of an electric-photochemical hybrid micromotor by tilt rectification. ACS Nano. 2020;14:8658–8667. doi: 10.1021/acsnano.0c03022. PubMed DOI

Xiao Z, et al. Bimetallic coatings synergistically enhance the speeds of photocatalytic TiO2 micromotors. Chem. Commun. 2020;56:4728–4731. doi: 10.1039/D0CC00212G. PubMed DOI

Ussia M, et al. Light-propelled nanorobots for facial titanium implants biofilms removal. Small. 2022;18:2200708. doi: 10.1002/smll.202200708. PubMed DOI

Sachs J, Kottapalli SN, Fischer P, Botin D, Palberg T. Characterization of active matter in dense suspensions with heterodyne laser Doppler velocimetry. Colloid Polym. Sci. 2021;299:269–280. doi: 10.1007/s00396-020-04693-6. DOI

Chen X, et al. Highly efficient visible-light-driven Cu2O@CdSe micromotors adsorbent. Appl. Mater. Today. 2021;25:101200. doi: 10.1016/j.apmt.2021.101200. DOI

Zhang Y, Li Y, Yuan Y. Carbon quantum dot-decorated BiOBr/Bi2WO6 photocatalytic micromotor for environmental remediation and DFT calculation. ACS Catal. 2022;12:13897–13909. doi: 10.1021/acscatal.2c04149. DOI

Meijer JM, Rossi L. Preparation, properties, and applications of magnetic hematite microparticles. Soft Matter. 2021;17:2354–2368. doi: 10.1039/D0SM01977A. PubMed DOI

Xie H, et al. Reconfigurable magnetic microrobot swarm: multimode transformation, locomotion, and manipulation. Sci. Robot. 2019;4:aav8006. doi: 10.1126/scirobotics.aav8006. PubMed DOI

Yang L, et al. Autonomous environment-adaptive microrobot swarm navigation enabled by deep learning-based real-time distribution planning. Nat. Mach. Intell. 2022;4:480–493. doi: 10.1038/s42256-022-00482-8. DOI

Kang N, Zhu J, Zhang X, Wang H, Zhang Z. Reconfiguring self-assembly of photoresponsive hybrid colloids. J. Am. Chem. Soc. 2022;144:4754–4758. doi: 10.1021/jacs.2c00432. PubMed DOI

Mou F, et al. Phototactic flocking of photochemical micromotors. iScience. 2019;19:415–424. doi: 10.1016/j.isci.2019.07.050. PubMed DOI PMC

Palacci J, Sacanna S, Steinberg AP, Pine DJ, Chaikin PM. Living crystals of light-activated colloidal surfers. Science. 2013;339:936–940. doi: 10.1126/science.1230020. PubMed DOI

Singh DP, Choudhury U, Fischer P, Mark AG. Non-equilibrium assembly of light-activated colloidal mixtures. Adv. Mater. 2017;29:1701328. doi: 10.1002/adma.201701328. PubMed DOI

Che S, et al. Light-programmable assemblies of isotropic micromotors. Research. 2022;2022:9816562. doi: 10.34133/2022/9816562. PubMed DOI PMC

Wang L, Kaeppler A, Fischer D, Simmchen J. Photocatalytic TiO2 micromotors for removal of microplastics and suspended matter. ACS Appl. Mater. Interfaces. 2019;11:32937–32944. doi: 10.1021/acsami.9b06128. PubMed DOI

Guo X, et al. Phototactic micromotor assemblies in dynamic line formations for wide-range micromanipulations. J. Mater. Chem. C. 2022;10:5079–5087. doi: 10.1039/D1TC06078C. DOI

Peng X, Urso M, Ussia M, Pumera M. Shape-controlled self-assembly of light-powered microrobots into ordered microchains for cells transport and water remediation. ACS Nano. 2022;16:7615–7625. doi: 10.1021/acsnano.1c11136. PubMed DOI

Peng X, Urso M, Pumera M. Photo-fenton degradation of nitroaromatic explosives by light-powered hematite microrobots: when higher speed is not what we go for. Small Methods. 2021;5:2100617. doi: 10.1002/smtd.202100617. PubMed DOI

Li J, et al. Water-driven micromotors for rapid photocatalytic degradation of biological and chemical warfare agents. ACS Nano. 2014;8:11118–11125. doi: 10.1021/nn505029k. PubMed DOI

Parkinson GS. Iron oxide surfaces. Surf. Sci. Rep. 2016;71:272–365. doi: 10.1016/j.surfrep.2016.02.001. DOI

Luttrell T, et al. Why is anatase a better photocatalyst than rutile? Model studies on epitaxial TiO2 films. Sci. Rep. 2015;4:4043. doi: 10.1038/srep04043. PubMed DOI PMC

Moreira GF, Peçanha ER, Monte MBM, Leal Filho LS, Stavale F. XPS study on the mechanism of starch-hematite surface chemical complexation. Miner. Eng. 2017;110:96–103. doi: 10.1016/j.mineng.2017.04.014. DOI

Biesinger MC, et al. Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Cr, Mn, Fe, Co and Ni. Appl. Surf. Sci. 2011;257:2717–2730. doi: 10.1016/j.apsusc.2010.10.051. DOI

Biesinger MC, Lau LWM, Gerson AR, Smart RSC. Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Sc, Ti, V, Cu and Zn. Appl. Surf. Sci. 2010;257:887–898. doi: 10.1016/j.apsusc.2010.07.086. DOI

Zhou C, Zhang HP, Tang J, Wang W. Photochemically powered AgCl Janus micromotors as a model system to understand ionic self-diffusiophoresis. Langmuir. 2018;34:3289–3295. doi: 10.1021/acs.langmuir.7b04301. PubMed DOI

Rajagopal S, Paramasivam B, Muniyasamy K. Photocatalytic removal of cationic and anionic dyes in the textile wastewater by H2O2 assisted TiO2 and micro-cellulose composites. Sep. Purif. Technol. 2020;252:117444. doi: 10.1016/j.seppur.2020.117444. DOI

Palacci J, Sacanna S, Vatchinsky A, Chaikin PM, Pine DJ. Photoactivated colloidal dockers for cargo transportation. J. Am. Chem. Soc. 2013;135:15978–15981. doi: 10.1021/ja406090s. PubMed DOI

Lin Z, et al. Light-activated active colloid ribbons. Angew. Chem. - Int. Ed. 2017;56:13517–13520. doi: 10.1002/anie.201708155. PubMed DOI

Lin Z, et al. Magnetically actuated peanut colloid motors for cell manipulation and patterning. ACS Nano. 2018;12:2539–2545. doi: 10.1021/acsnano.7b08344. PubMed DOI

Debata S, Kherani NA, Panda SK, Singh DP. Light-driven microrobots: capture and transport of bacteria and microparticles in a fluid medium. J. Mater. Chem. B. 2022;10:8235–8243. doi: 10.1039/D2TB01367C. PubMed DOI

Wang X, et al. Multistimuli-responsive hydroplaning superhydrophobic microrobots with programmable motion and multifunctional applications. ACS Nano. 2022;16:14895–14906. doi: 10.1021/acsnano.2c05783. PubMed DOI

Peng X, Urso M, Balvan J, Masarik M, Pumera M. Self-propelled magnetic dendrite-shaped microrobots for photodynamic prostate cancer therapy. Angew. Chem. Int. Ed. 2022;61:e202213505. doi: 10.1002/anie.202213505. PubMed DOI

Peng Y, et al. Generic rules for distinguishing autophoretic colloidal motors. Angew. Chem. Int. Ed. 2022;61:e202116041. doi: 10.1002/anie.202116041. PubMed DOI

Lee SH, Liddell CM. Anisotropic magnetic colloids: a strategy to form complex structures using nonspherical building blocks. Small. 2009;5:1957–1962. doi: 10.1002/smll.200900135. PubMed DOI

Urso M, Ussia M, Pumera M. Smart micro- and nanorobots for water purification. Nat. Rev. Bioeng. 2023;1:236–251. doi: 10.1038/s44222-023-00025-9. PubMed DOI PMC

Ye H, et al. Design and fabrication of micro/nano-motors for environmental and sensing applications. Appl. Mater. Today. 2021;23:101007. doi: 10.1016/j.apmt.2021.101007. DOI

Shivalkar S, Gautam PK, Chaudhary S, Samanta SK, Sahoo AK. Recent development of autonomously driven micro/nanobots for efficient treatment of polluted water. J. Environ. Manag. 2021;281:111750. doi: 10.1016/j.jenvman.2020.111750. PubMed DOI

Tang FHM, Lenzen M, McBratney A, Maggi F. Risk of pesticide pollution at the global scale. Nat. Geosci. 2021;14:206–210. doi: 10.1038/s41561-021-00712-5. DOI

Carvalho FP. Pesticides, environment, and food safety. Food Energy Secur. 2017;6:48–60. doi: 10.1002/fes3.108. DOI

Camara MC, et al. Development of stimuli-responsive nano-based pesticides: emerging opportunities for agriculture. J. Nanobiotechnol. 2019;17:100. doi: 10.1186/s12951-019-0533-8. PubMed DOI PMC

González-Rodríguez RM, Rial-Otero R, Cancho-Grande B, Gonzalez-Barreiro C, Simal-Gándara J. A review on the fate of pesticides during the processes within the food-production chain. Crit. Rev. Food Sci. Nutr. 2011;51:99–114. doi: 10.1080/10408390903432625. PubMed DOI

Möhring N, et al. Pathways for advancing pesticide policies. Nat. Food. 2020;1:535–540. doi: 10.1038/s43016-020-00141-4. PubMed DOI

Loomis D, et al. Carcinogenicity of lindane, DDT, and 2,4-dichlorophenoxyacetic acid. Lancet Oncol. 2015;16:891–892. doi: 10.1016/S1470-2045(15)00081-9. PubMed DOI

Zheng X, et al. A carnation-like rGO/Bi2O2CO3/BiOCl composite: efficient photocatalyst for the degradation of ciprofloxacin. J. Mater. Sci. Mater. Electron. 2019;30:5986–5994. doi: 10.1007/s10854-019-00898-w. DOI

Lu Q, Zhang Y, Liu S. Graphene quantum dots enhanced photocatalytic activity of zinc porphyrin toward the degradation of methylene blue under visible-light irradiation. J. Mater. Chem. A. 2015;3:8552–8558. doi: 10.1039/C5TA00525F. DOI

He Z, Xia Y, Su J. Fabrication of novel AgBr/Bi24O31Br10 composites with excellent photocatalytic performance. RSC Adv. 2018;8:39187–39196. doi: 10.1039/C8RA08733D. PubMed DOI PMC

Pan D, et al. Synthesis, characterization and photocatalytic activity of mixed-metal oxides derived from NiCoFe ternary layered double hydroxides. Dalt. Trans. 2018;47:9765–9778. doi: 10.1039/C8DT01045E. PubMed DOI

Lim PF, et al. Mechanism insight of dual synergistic effects of plasmonic Pd-SrTiO3 for enhanced solar energy photocatalysis. Appl. Phys. A Mater. Sci. Process. 2020;126:550. doi: 10.1007/s00339-020-03739-4. DOI

Reguero-Márquez GA, et al. Photodegradation of 2,4-D (dichlorophenoxyacetic acid) with Rh/TiO2; comparative study with other noble metals (Ru, Pt, and Au) RSC Adv. 2022;12:25711–25721. doi: 10.1039/D2RA03552A. PubMed DOI PMC

Silva RT, et al. Effective photodegradation of 2,4-dichlorophenoxyacetic acid on TiO2 nanocrystals anchored on SBA-15 mesoporous material. Int. J. Environ. Sci. Technol. 2022;19:11905–11918. doi: 10.1007/s13762-022-03934-1. DOI

Limón-Rocha I, et al. Co, Cu, Fe, and Ni deposited over TiO2 and their photocatalytic activity in the degradation of 2,4-dichlorophenol and 2,4-dichlorophenoxyacetic acid. Inorganics. 2022;10:157. doi: 10.3390/inorganics10100157. DOI

Akintunde OO, et al. Disinfection and photocatalytic degradation of organic contaminants using visible light-activated GCN/Ag2CrO4 nanocomposites. Catalysts. 2022;12:943. doi: 10.3390/catal12090943. DOI

Hernández-Del Castillo PC, Oliva J, Rodriguez-Gonzalez V. An eco-friendly and sustainable support of agave-fibers functionalized with graphene/TiO2:SnO2 for the photocatalytic degradation of the 2,4-D herbicide from the drinking water. J. Environ. Manag. 2022;317:115514. doi: 10.1016/j.jenvman.2022.115514. PubMed DOI

Lam SM, et al. Surface decorated coral-like magnetic BiFeO3 with Au nanoparticles for effective sunlight photodegradation of 2,4-D and E. coli inactivation. J. Mol. Liq. 2021;326:115372. doi: 10.1016/j.molliq.2021.115372. DOI

Hernández-Moreno EJ, et al. Synthesis, characterization, and visible light-induced photocatalytic evaluation of WO3/NaNbO3 composites for the degradation of 2,4-D herbicide. Mater. Today Chem. 2021;19:100406. doi: 10.1016/j.mtchem.2020.100406. DOI

Zhang Z, Zhao A, Wang F, Ren J, Qu X. Design of a plasmonic micromotor for enhanced photo-remediation of polluted anaerobic stagnant waters. Chem. Commun. 2016;52:5550–5553. doi: 10.1039/C6CC00910G. PubMed DOI

Lukong VT, Ukoba K, Jen TC. Review of self-cleaning TiO2 thin films deposited with spin coating. Int. J. Adv. Manuf. Technol. 2022;122:3525–3546. doi: 10.1007/s00170-022-10043-3. DOI

Obregón S, Rodríguez-González V. Photocatalytic TiO2 thin films and coatings prepared by sol–gel processing: a brief review. J. Sol. Gel Sci. Technol. 2022;102:125–141. doi: 10.1007/s10971-021-05628-5. DOI

Sugimoto T, Itoh H, Mochida T. Shape control of monodisperse hematite particles by organic additives in the gel-sol system. J. Colloid Interface Sci. 1998;205:42–52. doi: 10.1006/jcis.1998.5588. PubMed DOI

Wang W, Chiang TY, Velegol D, Mallouk TE. Understanding the efficiency of autonomous nano- and microscale motors. J. Am. Chem. Soc. 2013;135:10557–10565. doi: 10.1021/ja405135f. PubMed DOI

Urso, M., Ussia, M., Peng, X., Oral, C. M. & Pumera, M. Reconfigurable self-assembly of photocatalytic magnetic microrobots for water purification. Figshare10.6084/m9.figshare.24013836 (2023). PubMed PMC

Magnetic Microrobot Swarms with Polymeric Hands Catching Bacteria and Microplastics in Water

Reconfigurable self-assembly of photocatalytic magnetic microrobots for water purification