Magnetic Microswarm and Fluoroscopy‐Guided Platform for Biofilm Eradication in Biliary Stents

Abstract

substances (EPSs) that protect bacterial cells and show enhanced resistance to conventional antibiotics and the immune system. [1] Biofilms and their associated infections pose a significant threat to public health, including medical complications and persistent infections that are often life-threatening. Biofilms are very widely distributed on diverse surfaces, including humans, and the contamination of medical devices and implants, especially forming in inaccessible regions, such as the inner wall of biliary stent implants. [2] The purpose of biliary stent implants is to prevent obstruction during endoscopic retrograde cholangiopancreatography. [3] Due to the limited diameter of biliary stents, patients who require longterm stent placement may experience recurrent biliary stent blockage, which may be life-threatening. The adhesion of microorganisms on stent lumen surface and formation of biofilms play an essential role in the initiation of the blockage process and the subsequent clogging of the stent. [4][5][6][7] The biofilm adhering to biliary stents is a complex mixture of several species of bacterial such as Escherichia coli, Enterococcus faecalis, Klebsiella, Bacillus, and Candida tropicalis. [3] Repeated replacement of biliary stents to avoid blockage is unpleasant and costly for patients, and an effective solution is to remove Biofilm eradication from medical implants is of fundamental importance, and the treatment of biofilm-associated pathogen infections on inaccessible biliary stents remains challenging. Magnetically driven microrobots with controlled motility, accessibility to the tiny lumen, and swarm enhancement effects can physically disrupt the deleterious biostructures while not developing drug resistance. Magnetic urchin-like capsule robots (MUCRs) loaded with magnetic liquid metal droplets (MLMDs, antibacterial agents) are designed using natural sunflower pollen, and the therapeutic effect of swarming MUCR@MLMDs is explored for eradicating complex mixtures of bacterial biofilm within biliary stents collected from patients. The external magnetic field triggers the emergence of the microswarm and induces MLMDs to transform their shape into spheroids and rods with sharp edges. The inherent natural microspikes of MUCRs and the obtained sharp edges of MLMDs actively rupture the dense biological matrix and multiple species of embedded bacterial cells by exerting mechanical force, finally achieving synergistic biofilm eradication. The microswarm is precisely and rapidly deployed into the biliary stent via endoscopy in 10 min. Notably, fluoroscopy imaging is used to track and navigate the locomotion of microswarm in biliary stents in real-time. The microswarm has great potential for treating bacterial biofilm infections associated with medical implants.

Medical Swimming Cellbots

“…Photosensitive algae, [2b,29] spores, [ 30 ] and other types of cells are also applied to fabricate swimming cellbots, such as green microalgae microrobots controlled by optical force, Ganoderma lucidum spore‐based microrobots, as well as magnetic urchin‐like capsule robots fabricated from sunflower pollen grains. [ 31 ] Biomaterials like spores and grains are easy to obtain in a large quantity, and own good biocompatibility due to degradability. Subsequently, due to the urgent needs of biomedical applications, more cells with higher biocompatibility and lower immunogenicity are applied to the construction of cellbots, such as red blood cells, [ 32 ] macrophages, [26b,33] and so on.…”

Pollen‐Based Magnetic Microrobots are Mediated by Electrostatic Forces to Attract, Manipulate, and Kill Cancer Cells

“…[11][12][13][14][15][16] Besides, such materials ensure their abundance to mass produce as micro/nanorobots and also offer biocompatibility. Plant-based micro/nanorobots, e.g., pollen microparticles, [17][18][19] plant tissues, [20,21] plant cells, [22] and microalgae, [23,24] are of particular interest due to their biocompatibility and ability to be easily modified to perform multiple functions.…”

Multiscale Magnetic Hydrogel Robot with a Core–Shell Structure for Active Targeted Delivery

“…Over the past decades, small-scale swimming robots (SSRs) with dimensions ranging from nanometer to millimeter have proven to be promising drug carriers due to their ability of active movement. − Besides, the applications of SSRs can be extended to clinical diagnosis, cell manipulation, environmental remediation, and minimally invasive surgery. − These robots can be classified by the actuation methods, such as light-actuated, acoustic-actuated, fuel-actuated, , or magnetically actuated methods. , Among them, robots actuated by the magnetic field show superior performance in active targeted delivery owing to the advantages of this actuation strategy such as strong penetration, remote control, and advanced biological compatibility. , Recent progress in applying SSRs in active drug delivery is mainly focused on the development of fabrication techniques, materials, and motion control of robots . Diverse manufacturing methods, such as 3D laser lithography, template-assisted deposition, or self-assembly, have been exploited to rationally design the shape and functionality of SSRs. − Micro-/nanorobots of various shapes, including spherical, helical, wire-like, and peanut-shaped, have been proposed and proven to be effective drug carriers through in vivo or in vitro experiments.…”