Near-Infrared Light-Driven Mesoporous SiO2 /Au Nanomotors for Eradication of Pseudomonas aeruginosa Biofilm.

Bacterial biofilms are linked to several diseases and cause resistant and chronic infections in immune-compromised patients. Nanomotors comprise a new field of research showing a great promise within biomedicine but pose challenges in terms of biocompatibility. Nanomotors propelled by thermophoresis could overcome this challenge, as they leave no waste product during propulsion. In this study, mesoporous-silica nanoparticles are coated with a thin layer of gold to make nanomotors, which can be driven by near-infrared (NIR) light irradiation. The prepared mesoporous SiO2 -Au nanomotors exhibit efficient self-propulsion when exposed to NIR irradiation, they penetrate deep through a biofilm matrix, and disperse the biofilm in situ due to the photothermal effect on the Au part of the nanomotors. The velocities of such nanomotors are investigated at different wavelengths and laser powers. Furthermore, the study examines the ability of these nanomotors to eradicate Pseudomonas aeruginosa (P. aeruginosa) biofilm under NIR light irradiation. The conducted study shows that the nanomotor's velocity increases with increasing laser power. The mesoporous SiO2 /Au nanomotors show excellent capabilities to eradicate P. aeruginosa biofilms even under short (30 s-3 min) irradiation time. This study shows great promise for overcoming the challenges related to bacterial biofilm eradication.

Microscopic Cascading Devices for Boosting Mucus Penetration in Oral Drug Delivery-Micromotors Nesting Inside Microcontainers.

In the case of macromolecules and poorly permeable drugs, oral drug delivery features low bioavailability and low absorption across the intestinal wall. Intestinal absorption can be improved if the drug formulation could be transported close to the epithelium. To achieve this, a cascade delivery device comprising Magnesium-based Janus micromotors (MMs) nesting inside a microscale containers (MCs) has been conceptualized. The device aims at facilitating targeted drug delivery mediated by MMs that can lodge inside the intestinal mucosa. Loading MMs into MCs can potentially enhance drug absorption through increased proximity and unidirectional release. The MMs will be provided with optimal conditions for ejection into any residual mucus layer that the MCs have not penetrated. MMS confined inside MCs propel faster in the mucus environment as compared to non-confined MMs. Upon contact with a suitable fuel, the MM-loaded MC itself can also move. An in vitro study shows fast release profiles and linear motion properties in porcine intestinal mucus compared to more complex motion in aqueous media. The concept of dual-acting cascade devices holds great potential in applications where proximity to epithelium and deep mucus penetration are needed.

Functional 2D Germanene Fluorescent Coating of Microrobots for Micromachines Multiplexing.

Micromachines are at the forefront of materials research as they are self-propelled, smart autonomous systems capable of acting as an intelligent matter. One of the obstacles the field faces is tracking individual micromachines carrying molecular cargo from the rest of the micromachines. Highly stable fluorescent markers based on chemically modified 2D germanene compounds are developed. Two different 2D germanene derivatives, 4-fluorophenylgermanane (2D-Ph-Ge) and methylgermanane (2D-Me-Ge), exhibit different fluorescence under UV light irradiation (excitation at 365 nm), which allows one particular micromotor to be easily distinguished in a mixture of micromotors. This offers a paradigm shift toward a new approach of multiplex detection of self-propelled micromachines. The utility is demonstrated on a drug delivery system, where micromachines carrying a drug are labeled with 2D-Ph-Ge with blue emission while bare micromachines are labeled by 2D-Me-Ge with red emission. This approach of functional fluorescent labeling will pave the way to multiple simultaneous functionalized micromachines identification in complex environments.

Cloisite Microrobots as Self-Propelling Cleaners for Fast and Efficient Removal of Improvised Organophosphate Nerve Agents.

Naturally available microclays are well-known materials with great adsorption capabilities that are available in nature in megatons quantities. On the contrary, artificial nanostructures are often available at high cost via precision manufacturing. Such precision nanomanufacturing is also typically used for fabrication of self-propelled micromotors and nanomachines. Herein, we utilized naturally available Cloisite microclays to fabricate autonomous self-propelled microrobots and demonstrated their excellent performances in pesticide removal due to their excellent adsorption capability. Six different modified Cloisite microrobots were investigated by sputtering their microclays with platinum (Pt) for the fabrication of platinum-Cloisite (Pt-C) microrobots. The obtained microrobots displayed fast velocities (v > 110 µm/s) with fast and efficient enhanced removal of the pesticide fenitrothion, which is also considered as improvised nerve agent. The fabricated Pt-C microrobots exhibited low cytotoxicity even at high concentrations when incubated with human lung carcinoma epithelial cells, which make them safe for human handling.

Corrosion due to ageing influences the performance of tubular platinum microrobots.

Autonomous self-propelled nano and microrobots are in the forefront of materials research. The micromachines are typically prepared in batches, stored and subsequently used. We show here that the storage of platinum tubular catalytic microrobots in water causes their corrosion which results in their lower mobility and performance. This has important implications for the construction and storage of these autonomous micromotors.