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Multifunctional nanorobots facilitate pollutant degradation and bacteria elimination

29 Aug 2025

Chemical pollution, pathogenic bacteria, and biofilms, a community of microorganisms embedded in a slimy matrix, present threats to public health. To address these challenges, Professor Ken Leung, Associate Professor of the Department of Chemistry at HKBU, in collaboration with scientists from the University of Science and Technology of China, Hefei University of Technology, and the Dongcheng branch of the First Affiliated Hospital of Anhui Medical University, developed a multifunctional nanorobot, which demonstrates capabilities in breaking down organic pollutants, exhibits antibacterial properties, and removes biofilms.

The research findings have been published in the academic journal Advanced Healthcare Materials, and the invention holds potential for broad applications in antibacterial treatments, sewage management, and biomedicine.

The nanorobot designed and fabricated by the collaborative research team has a hollow spherical structure with its core composed of iron oxide. This enables control of the nanorobot’s movement with the application of magnetic fields, so that the nanorobot can navigate along predetermined paths. Its middle layer consists of silver and gold bi-metallic nanorods, which not only act as catalyst for chemical reactions that facilitate the degradation of organic pollutants, but also inhibit the growth or disrupt the function of bacterial cells. Moreover, the nanorobot’s outer layer is made of polydopamine, a biocompatible material that protects and stabilises the inner components, while its large cavity and mesoporous structure can be used as drug carriers.

To test the efficacy of the nanorobot in pollutant degradation, the research team created miniature wastewater pools. They introduced an organic pollutant from industrial and agricultural activities, and an organic dye typically found in industrial wastewater, into two of the chambers of the pools. Driven by magnetic fields, the nanorobots accurately moved to the two chambers and stayed there for one minute. Tests revealed that the levels of pollutants in the chambers were reduced significantly, demonstrating the nanorobots’ capabilities in facilitating pollutant degradation.

The research further showcased the nanorobot’s antibacterial capability. It can act as a carrier to load zinc phthalocyanine, a photosensitiser that absorbs light and transfers the energy to facilitate chemical reactions for therapeutic applications, including the disruption of bacterial cell structure. When magnetic fields, near-infrared laser and xenon lamp irradiation were applied together, the nanorobot loaded with zinc phthalocyanine achieved up to 99.99% inhibition of Escherichia coli and Staphylococcus aureus bacterial proliferation.

In addition, the magnetic propulsion capability of the nanorobot loaded with zinc phthalocyanine enables it to effectively remove bacterial biofilms. The study highlighted the potential of the nanorobot in addressing biofilm-associated infections and blockages in confined spaces like catheters.

Professor Leung said: “Our research results show that the multifunctional nanorobot developed by our research team exhibits precise catalytic capabilities, high antibacterial activity, and effective biofilm removal properties. Its mobility navigated by magnetic fields enables pollutant degradation and antibacterial activities to be conducted in a controlled, precise and effective manner. This multifunctional nanorobot possesses significant potential for applications in sewage treatment, biomedicine, and other fields.”