The occurrence of synthetic and natural hormones in an aqueous environment poses significant risks to humans because of their endocrine-disrupting activity. Autonomous self-propelled and remotely actuated nano/microrobots have emerged as a new field that encompasses a wide range of potential applications, including sensing, detection and elimination/degradation of emerging pollutants. In this work, we develop programmable polypyrrole-based (PPy, outer functional layer) microrobots incorporated with a Pt catalytic layer and paramagnetic iron nanoparticles (Fe3O4) to provide self-propulsion and a magnetic response for the highly efficient removal of oestrogenic pollutants. As the pH of the tested water alters, the surface charge of PPy/Fe3O4/Pt microrobots gradually changes, leading to affinity modulation. As microrobots move inside the solution, they collect oestrogen fibres and subsequently weave macroscopic webs on the surface. Our results suggest that motion-controllable microrobots with adjustable surface chemistry could provide a suitable platform for the highly efficient removal of hormonal pollutants.
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Data for the figures presented in this paper are provided in the Supplementary Information and in the FigShare repository (https://doi.org/10.6084/m9.figshare.12979910.v1). Source data are provided with this paper.
Credi, A. Nanomachines. Fundamentals and applications. By Joseph Wang. Angew. Chem. Int. Ed. 53, 4274–4275 (2014).
Srivastava, S. K., Clergeaud, G., Andresen, T. L. & Boisen, A. Micromotors for drug delivery in vivo: the road ahead. Adv. Drug Deliv. Rev. 138, 41–55 (2019).
Khezri, B. et al. Ultrafast electrochemical trigger drug delivery mechanism for nanographene micromachines. Adv. Funct. Mater. 29, 1806696 (2019).
Mohsen, B.-M. S. et al. Recoverable bismuth-based microrobots: capture, transport, and on-demand release of heavy metals and an anticancer drug in confined spaces. ACS Appl. Mater. Interfaces 11, 13359–13369 (2019).
Wang, B., Zhang, Y. & Zhang, L. Recent progress on micro- and nano-robots: towards in vivo tracking and localization. Quant. Imaging Med. Surg. 8, 461–479 (2018).
Erkoc, P. et al. Mobile microrobots for active therapeutic delivery. Adv. Ther. 2, 1800064 (2019).
Ornes, S. Inner workings: medical microrobots have potential in surgery, therapy, imaging and diagnostics. Proc. Natl Acad. Sci. USA 114, 12356–12358 (2017).
Ying, Y. & Pumera, M. Micro/nanomotors for water purification. Chem. Eur. J. 25, 106–121 (2019).
Kong, L., Rosli, N. F., Chia, H. L., Guan, J. & Pumera, M. Self-propelled autonomous Mg/Pt Janus micromotor interaction with human cells. Bull. Chem. Soc. Jpn 92, 1754–1758 (2019).
Wang, H. & Pumera, M. Emerging materials for the fabrication of micro/nanomotors. Nanoscale 9, 2109–2116 (2017).
Khezri, B., Novotný, F., Moo, J. G. S., Nasir, M. Z. M. & Pumera, M. Confined bubble-propelled microswimmers in capillaries: wall effect, fuel deprivation and exhaust product excess. Small 16, e2000413 (2020).
Hwang, J. et al. A remotely steerable Janus micromotor adsorbent for the active remediation of Cs-contaminated water. J. Hazard. Mater. 369, 416–422 (2019).
Ying, Y., Pourrahimi, A. M., Sofer, Z., Matějková, S. & Pumera, M. Radioactive uranium preconcentration via self-propelled autonomous microrobots based on metal–organic frameworks. ACS Nano 13, 11477–11487 (2019).
Singh, V. V. & Wang, J. Nano/micromotors for security/defense applications. A review. Nanoscale 7, 19377–19389 (2015).
Singh, V. V., Martin, A., Kaufmann, K., D. S. de Oliveira, S. & Wang, J. Zirconia/graphene oxide hybrid micromotors for selective capture of nerve agents. Chem. Mater. 27, 8162–8169 (2015).
Dong, Y. et al. A substrate-free graphene oxide-based micromotor for rapid adsorption of antibiotics. Nanoscale 11, 4562–4570 (2019).
Wang, L., Kaeppler, A., Fischer, D. & Simmchen, J. Photocatalytic TiO2 micromotors for removal of microplastics and suspended matter. ACS Appl. Mater. Interfaces 11, 32937–32944 (2019).
He, X., Bahk, Y. K. & Wang, J. Organic dye removal by MnO2 and Ag micromotors under various ambient conditions: the comparison between two abatement mechanisms. Chemosphere 184, 601–608 (2017).
Zhan, Z. et al. Visible light driven recyclable micromotors for ‘on-the-fly’ water remediation. Mater. Lett. 258, 126825 (2020).
Pourrahimi, A. M., Villa, K., Ying, Y., Sofer, Z. & Pumera, M. ZnO/ZnO2/Pt Janus micromotors propulsion mode changes with size and interface structure: enhanced nitroaromatic explosives degradation under visible light. ACS Appl. Mater. Interfaces 10, 42688–42697 (2018).
Khezri, B., Beladi Mousavi, S. M., Sofer, Z. & Pumera, M. Recyclable nanographene-based micromachines for the on-the-fly capture of nitroaromatic explosives. Nanoscale 11, 8825–8834 (2019).
Orozco, J. et al. Micromotor-based high-yielding fast oxidative detoxification of chemical threats. Angew. Chem. Int. Ed. 52, 13276–13279 (2013).
Srivastava, S. K., Guix, M. & Schmidt, O. G. Wastewater mediated activation of micromotors for efficient water cleaning. Nano Lett. 16, 817–821 (2016).
Clouzot, L., Marrot, B., Doumenq, P. & Roche, N. 17α‐ethinylestradiol: an endocrine disrupter of great concern. Analytical methods and removal processes applied to water purification. A review. Environ. Prog. 27, 383–396 (2008).
Villa, K., Parmar, J., Vilela, D. & Sánchez, S. Core–shell microspheres for the ultrafast degradation of estrogen hormone at neutral pH. RSC Adv. 8, 5840–5847 (2018).
Hyun-ShikChang, K.-Ho. Choo, Lee, B. & Choi, S.-J. The methods of identification, analysis, and removal of endocrine disrupting compounds (EDCs) in water. J. Hazard. Mater. 172, 1–12 (2009).
Kibambe, M. G., Momba, M. N. B., Daso, A. P., Zijl, M. C. V. & Coetzee, M. A. A. Efficiency of selected wastewater treatment processes in removing estrogen compounds and reducing estrogenic activity using the T47D-KBLUC reporter gene assay. J. Environ. Manage. 260, 110135 (2020).
Swart, N. & Pool, E. Rapid detection of selected steroid hormonesfrom sewage effluents using an ELISA in the KuilsRiver water catchment area, South Africa. J. Immunoassay Immunochem. 28, 395–408 (2007).
Bexfield, L. M., Toccalino, P. L., Belitz, K., Foreman, W. T. & Furlong, E. T. Hormones and pharmaceuticals in groundwater used as a source of drinking water across the United States. Environ. Sci. Technol. 53, 2950–2960 (2019).
Ying, G.-G., Kookana, R. S. & Ru, Y.-J. Occurrence and fate of hormone steroids in the environment. Environ. Int. 28, 545–551 (2002).
Sarmah, A. K., Northcott, G. L., Leusch, F. D. L. & Tremblay, L. A. A survey of endocrine disrupting chemicals (EDCs) in municipal sewage and animal waste effluents in the Waikato region of New Zealand. Sci. Total Environ. 355, 135–144 (2006).
Soto, A. M. et al. Androgenic and estrogenic activity in water bodies receiving cattle feedlot effluent in Eastern Nebraska, USA. Environ. Health Perspect. 112, 346–352 (2004).
Ting, Y. F. & Praveena, S. M. Sources, mechanisms and fate of steroid estrogens in wastewater treatment plants: a mini review. Environ. Monit. Assess. 189, 178 (2017).
Grassi, M., Kaykioglu, G., Belgiorno, V. & Lofrano, G. in Emerging Compounds Removal from Wastewater (ed. Lofrano, G.) 15–37 (Springer, 2012).
Silva, C. P., Otero, M. & Esteves, V. Processes for the elimination of estrogenic steroid hormones from water: a review. Environ. Pollut. 165, 38–58 (2012).
Moreira, F. C., Boaventura, R. A. R., Brillas, E. & Vilar, V. J. P. Electrochemical advanced oxidation processes: a review on their application to synthetic and real wastewaters. Appl. Catal. B Environ. 202, 217–261 (2017).
Akagi, K. Interdisciplinary chemistry based on integration of liquid crystals and conjugated polymers: development and progress. Bull. Chem. Soc. Jpn 92, 1509–1555 (2019).
Liu, P. et al. Recent advancements of polyaniline-based nanocomposites for supercapacitors. J. Power Sources 424, 108–130 (2019).
Wei, L. et al. Determination of estrogens in milk using polypyrrole fiber-mediated solid-phase extraction followed by high performance liquid chromatography. J. Braz. Chem. Soc. 29, 2137–2143 (2018).
Mohammadi, A., Ameli, A. & Alizadeh, N. Headspace solid-phase microextraction using a dodecylsulfate-doped polypyrrole film coupled to ion mobility spectrometry for the simultaneous determination of atrazine and ametryn in soil and water samples. Talanta 78, 1107–1114 (2009).
Yuan, X. et al. Photocatalytic degradation of organic pollutant with polypyrrole nanostructures under UV and visible light. Appl. Catal. B Environ. 242, 284–292 (2019).
Zhang, X., Zhang, J., Song, W. & Liu, Z. Controllable synthesis of conducting polypyrrole nanostructures. J. Phys. Chem. B 110, 1158–1165 (2006).
Gao, W. et al. Cargo-towing fuel-free magnetic nanoswimmers for targeted drug delivery. Small 8, 460–467 (2012).
Karshalev, E. et al. Utilizing iron’s attractive chemical and magnetic properties in microrocket design, extended motion and unique performance. Small 13, 1700035 (2017).
Hunter, R. J. Zeta Potential in Colloid Science: Principles and Applications (Academic Press, 1981).
Zhang, X. & Bai, R. Surface electric properties of polypyrrole in aqueous solutions. Langmuir 19, 10703–10709 (2003).
Stejskal, J. et al. Polypyrrole salts and bases: superior conductivity of nanotubes and their stability towards the loss of conductivity by deprotonation. RSC Adv. 6, 88382–88391 (2016).
Samanta, D., Meiser, J. L. & Zare, R. N. Polypyrrole nanoparticles for tunable, pH-sensitive and sustained drug release. Nanoscale. 7, 9497–9504 (2015).
Zhang, X. & Bai, R. Mechanisms and kinetics of humic acid adsorption onto chitosan-coated granules. J. Colloid Interface Sci. 264, 30–38 (2003).
M.P. was supported by the Ministry of Education, Youth and Sports (Czech Republic) grant no. LL2002 under the ERC CZ programme. B.K. was supported by the Czech Science Foundation (GACR no. 20-20201S).
The authors declare no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Extended Data Fig. 1 SEM images and EDS mapping of microrobots.
a, EDS after electropolymerization of PPy (PPy base tube); b, EDS after Pt electrodeposition (PPy/Pt tube) and also; c, Final PPy/Fe3O4/Pt microrobots; d, SEM and corresponding EDS mapping for Fe and Pt with EDS spectra of the observed area; e, STEM image of catalytic Pt layer inside the tube.
Extended Data Fig. 2 SEM images of tubular surface morphologies.
a, Pristine PPy tube (without Pt electrodeposition and also Fe3O4 NPs incorporation); b, PPy/Pt tube, and c, PPy/Fe3O4/Pt microrobots.
Extended Data Fig. 3 PPy/Fe3O4/Pt microrobots’ motion characterization.
a, Their speed in relation to H2O2 concentration and b, Corresponding microscopic images of the microrobots’ motion in different H2O2 concentration.
Extended Data Fig. 4 Selectivity study of removal efficiency of PPy-based microrobots.
a, Section i-ii represents removal efficiency for Pyrranine dye with microrobots (ii) and without (i); section iii-iv represents experiments carried out with Rhodamine B with microrobots (iv) and without (iii); section v-vi represents removal efficiency for Methylene Blue with microrobots (v) and without (vi); section vii-viii serves for comparison of removal efficiency for 17α-ethynylestradiol with microrobots (viii) and without (vii); b, absorption spectra of organic dyes and c, their chemical structures.
Extended Data Fig. 5 Numerical simulation of the pressure and fluid velocity.
a, Numerical simulation of a 12.4 × 4.4 µm microrobot speeding at 140 µm s−1 through water.; b, Similar simulated situation but with the addition of mass to the microrobot body (Colormap represents pressure field; red arrows represent fluid flow with the microrobot as a frame of reference).
Supplementary Figs. 1–6, Table1 and notes 1–5.
Supplementary Video 1
The synergic effect of bubble and magnetic propulsion in navigating of microrobots.
Supplementary Video 2
The directional microrobot reorientation in the presence of a rotating magnetic field.
Supplementary Video 3
The transformation of the fibrous texture to one compact piece which can be easily removed by a static external magnetic field.
Source Data Fig. 3
Data for presented ζ-potential measurements.
Source Data Fig. 4
Removal efficiency for hormones.
Source Data Fig. 5
XPS source data.
Source Data Extended Data Fig. 3
Statistic source data from speed tracking of microrobots propelled by hydrogen peroxide.
Source Data Extended Data Fig. 4
Selectivity data source.
Source Data Extended Data Fig. 5
Source data for numerical simulation.
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Dekanovsky, L., Khezri, B., Rottnerova, Z. et al. Chemically programmable microrobots weaving a web from hormones. Nat Mach Intell 2, 711–718 (2020). https://doi.org/10.1038/s42256-020-00248-0
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