A magnetic field-driven multi-functional "medical ship" for intestinal tissue collection in vivo

MOF-Modified Microrollers for Bioimaging and Sustained Antibiotic Delivery

Central nervous system (CNS) infections caused by neurosurgery or intrathecal injection of contaminated cerebrospinal fluid are a common and difficult complication. Drug-delivery microrobots are among the latest solutions proposed for antibacterial applications. However, there is a lack of research into developing microrobots with the ability to sustain antibody delivery while can move efficiently in the CNS. Here, biocompatible antibacterial metal-organic framework (MOF)-modified microrollers (MMRs) to combat CNS infections are proposed. The MMRs are iron-based metal-organic framework (NH2-MIL-101(Fe)) modified for enhanced adsorption and Fe/Al coated for magnetic actuation and biocompatibility. The MMRs have demonstrated a faster and unhindered magnetically actuated motion on the uneven biological tissue surface in an organ-on-a-chip that mimicked the CNS compared to it on smooth surface. CFD results consistently align with the experimental findings. The MMRs can be loaded with rhodamine 6G for bioimaging, allowing them to be imaged through sections of the main human tissues by fluorescence microscopy, or tetracycline hydrochloride for antibiotic delivery, allowing them to inhibit the growth of Staphylococcus aureus biofilms by sustained release of antibiotics for 9 days. This study provides a strategy to integrate high-capacity adsorption material with magnetically actuated locomotion for long-term targeted antibacterial applications in biological environments.

Mimicking Motor Proteins: Wall-Guided Self-Navigation of Microwheels

Untethered micro/nanorobots (MNRs) show great promise in biomedicine. However, high-precision targeted in vivo navigation of MNRs into both deep and tiny microtube networks comes with big challenges because the present medical imaging cannot simultaneously meet the requirements of high resolution, high penetration depth, and high real-time performance. Inspired by intracellular motor proteins that transport cargo along cytoskeletal tracks, this study proposed a microtube inwall-guided targeted self-navigation strategy of magnetic microwheels (μ-wheels) that relies only on interactions with a microtube inwall, compared to conventional techniques that rely on real-time imaging and tracking of MNRs. By presetting the direction of the rotating magnetic field, the μ-wheel realized targeted navigation along the inwall. The propulsion principles behind it are elaborated. The targeted self-navigation of the μ-wheels in three-dimensional microtube networks, a spiral microtube, and an intrahepatic bile duct of a pig was conducted. Lastly, based on the strategy, a practical tumor early detection method was proposed and verified by means of magnetic resonance imaging. The microtube inwall-guided targeted self-navigation strategy reduces the dependence of in vivo targeted navigation of MNRs on the real-time performance of medical imaging technology and greatly contributes to the development of MNRs in biomedical applications.

Light-driven nanomotors with reciprocating motion and high controllability based on interference techniques

In this paper, we investigate the controlled movement of optically trapped nano-particles in an interference optical lattice. The suggested interferometric optical tweezers setup utilizes the superposition of three orthogonal Gaussian standing waves to create 3D optical lattices. Dynamic control over the constructed lattices can be achieved simply by changing the incident beam parameters using a polarizer or a phase shifter. The trapping properties of the generated optical lattices for a dielectric Rayleigh particle are numerically evaluated using a MATLAB program. The simulation results showed that the generated lattices can be translated by altering the relative phase between the interfering beams. More complex transformations and geometries can be achieved by changing other properties of the interfering beams such as the polarization state. This simple setup enables the construction of a rich variety of dynamic optical lattices and offers promising applications in colloidal and biological science such as controlling the diffusion of colloidal particles and stretching or compressing tethered polymeric molecules. This interferometric method can also be used in light-driven nanomotors with high controllability.