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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.
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Reconfigurable microbots folded from simple colloidal chains
To overcome the reversible nature of low-Reynolds-number flow, a variety of biomimetic microrobotic propulsion schemes and devices capable of rapid transport have been developed. However, these approaches have been typically optimized for a specific function or environment and do not have the flexibility that many real organisms exhibit to thrive in complex microenvironments. Here, inspired by adaptable microbes and using a combination of experiment and simulation, we demonstrate that one-dimensional colloidal chains can fold into geometrically complex morphologies, including helices, plectonemes, lassos, and coils, and translate via multiple mechanisms that can be varied with applied magnetic field. With chains of multiblock asymmetry, the propulsion mode can be switched from bulk to surface-enabled, mimicking the swimming of microorganisms such as flagella-rotating bacteria and tail-whipping sperm and the surface-enabled motion of arching and stretching inchworms and sidewinding snakes. We also demonstrate that reconfigurability enables navigation through three-dimensional and narrow channels simulating capillary blood vessels. Our results show that flexible microdevices based on simple chains can transform both shape and motility under varying magnetic fields, a capability we expect will be particularly beneficial in complex in vivo microenvironments.
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- PAR ID:
- 10172846
- Publisher / Repository:
- Proceedings of the National Academy of Sciences
- Date Published:
- Journal Name:
- Proceedings of the National Academy of Sciences
- Volume:
- 117
- Issue:
- 31
- ISSN:
- 0027-8424
- Page Range / eLocation ID:
- p. 18186-18193
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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