Self-propelled nano- and micromachines have immense potential as autonomous seek-and-act devices in biomedical applications. In this study, we present microrobots constructed with inherently biocompatible materials and propulsion systems tailored to skin-related applications. Addressing the significant treatment challenge posed by methicillin-resistant Staphylococcus aureus (MRSA) skin infections, we demonstrate that photocatalytic titanium dioxide microrobots decorated with silver or platinum can effectively and rapidly eradicate MRSA biofilms grown on skin-mimicking membranes and porcine skin tissues. These microrobots are powered by hydrogen peroxide or ultraviolet light─agents considered toxic in high concentrations but commonly used in controlled amounts for skin disinfection and naturally encountered by the skin. By examining the effects of different metal coatings on the propulsion abilities of the microrobots, we show that these chemically propelled devices can eliminate biofilms without causing significant damage to the surrounding skin tissues, as confirmed by histological analysis. This work paves the way for the use of microrobots in skin-related biomedical applications, particularly in cases where traditional antibiotics are ineffective.

• Keywords
• Janus particles, biofilm, microrobots, skin infection, titanium dioxide,
• MeSH
• Anti-Bacterial Agents * pharmacology   chemistry   MeSH
• Biofilms drug effects   MeSH
• Skin * microbiology   drug effects   MeSH
• Methicillin-Resistant Staphylococcus aureus * drug effects   physiology   MeSH
• Hydrogen Peroxide chemistry   pharmacology   MeSH
• Platinum chemistry   pharmacology   MeSH
• Swine MeSH
• Robotics * instrumentation   MeSH
• Staphylococcal Skin Infections * drug therapy   microbiology   MeSH
• Silver chemistry   pharmacology   MeSH
• Titanium chemistry   pharmacology   MeSH
• Ultraviolet Rays MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anti-Bacterial Agents * MeSH
• Hydrogen Peroxide MeSH
• Platinum MeSH
• Silver MeSH
• Titanium MeSH
• titanium dioxide MeSH Browser

Ammonia (NH₃) production is a critical industrial process, as ammonia is a key component in fertilizers, essential for global agriculture and food production. However, the current method of synthesizing ammonia, the Haber-Bosch process, is highly energy-intensive, and relies on fossil fuels, contributing substantially to greenhouse gas emissions. Moreover, the centralized nature of the Haber-Bosch process limits its accessibility in remote or resource-limited areas. Photochemical synthesis of ammonia, provides an alternate lower energy, carbon-free pathway compared to the prevailing industrial methods. The photoconversion of nitrate anions, often present in wastewater, offers a greener, more sustainable, and energy-efficient route for both ammonia-generation and wastewater treatment. Photochemical and chemical synthesis of ammonia requires intensive mass-transfer processes, which limits the efficiency of the method. To change the game, in this work, a key new technology of ammonia-generation, a catalytic ammonia generation (AmmoGen) microrobot, which converts nitrate to ammonia using renewable light energy is reported. The magnetic propulsion of the AmmoGen microrobots significantly enhances mass-transfer, and expedites the photosynthesis of ammonia. Overall, this "proof-of-concept" study demonstrates that microrobots can aid in catalytic small molecule activation and generation of value-added products; and are envisaged to pave the way toward new sustainable technologies for catalysis.

• Keywords
• ammonia, magnetically driven, microrobots, nitrate reduction, photosynthesis,
• Publication type
• Journal Article MeSH