Spontaneous symmetry breaking propulsion of chemically coated magnetic microparticles

Abstract

Chemically coated micro/nanoparticles are often used in medicine to enhance drug delivery and increase drug up-take into specific areas of the body. Using a recently discovered spontaneous symmetry breaking propulsion mechanism, we demonstrate that chemically coated microparticles can swim through mucus solution under precise navigation and that certain functionalizations can dynamically change propulsion behavior. For this investigation biotin, Bitotin-PEG3-amine, and biotin chitosan were chemically functionalized onto the surfaces of magnetic microparticles using an avidin–biotin complex. These chemicals were chosen because they are used prolifically in drug delivery applications, with PEG and chitosan having well known mucoadhesive effects. Coated microparticles were then suspended in mucus synthesized from porcine stomach mucins and propelled using rotating magnetic fields. The relationship between different chemical coatings, microparticle velocity, and controllability were thoroughly explored and discussed. Results indicate that the biotinylated surface coatings altered the propulsion behavior of microparticles, with performance differences interlinked to both magnetic field properties and localized mucus properties. Precisely controlled drug carrying microparticles are envisioned to help supplant traditional drug delivery methods and enhance existing medical techniques utilizing micro/nanoparticles.

Propulsion of Planar V‐Shaped Microswimmers in a Conically Rotating Magnetic Field

“…rotation-translation coupling. [31,32] Despite recent theoretical advances in comprehending the driven propulsion of planar magnetic microswimmers, there is no systematic experimental investigation testing the role of geometry, magnetization, or field frequency and configuration, other than the experiment with the upscaled (cm-sized) 3D-printed propellers by Sachs et al [30] The use of planar microswimmers, which can be mass-produced through standard photolithography, is an attractive option in the field of microrobotics due to its ease of fabrication and potential for scalability and biocompatibility. [33,34] Planar magnetic microswimmers are prone to magnetize in their plane, while in-plane magnetized microswimmers typically exhibit bidirectional propulsion (i.e., parallel and antiparallel to the fieldrotation axis) when driven by a standard in-plane rotating magnetic field.…”

“…[ 30 ] Additionally, it has been demonstrated with spherical microbeads that nonlinear rheology of the suspending fluid can induce symmetry breaking and enable rotation‐translation coupling. [ 31,32 ] Despite recent theoretical advances in comprehending the driven propulsion of planar magnetic microswimmers, there is no systematic experimental investigation testing the role of geometry, magnetization, or field frequency and configuration, other than the experiment with the upscaled (cm‐sized) 3D‐printed propellers by Sachs et al [ 30 ] The use of planar microswimmers, which can be mass‐produced through standard photolithography, is an attractive option in the field of microrobotics due to its ease of fabrication and potential for scalability and biocompatibility. [ 33,34 ]…”

Microrobots for Targeted Delivery and Therapy in Digestive System

“…Targeted delivery and therapy in the digestive system may become one of the game changer applications of miniature robots since the digestive system contains a variety of small and difficult to reach lumens, examination and treatment even via endoscopic methods is encumbered with grave discomfort to the patient (i.e., gastroscopy and colonoscopy). − The digestive system shows a relatively low immune response compared with other organs, making the selection of carrier materials more diverse. To date, researchers have developed various microrobotic systems and strategies to tackle remote delivery of microrobots and payloads to the stomach and the intestine, by rationally considering and utilizing the local (micro)­environment. ,,− However, a lot of barriers exist in the digestive system. For example, the intestinal peristalsis and highly viscous mucus hamper high-precision actuation and control of miniature robots inside these lumens. − Similarly, biological barriers hinder the movement of microrobots along the GI tract .…”