Flagellated Janus particles for multimodal actuation and transport

Abstract

Catalytic Janus particles rely on chemical decomposition to self-propel and have displayed enormous potential for targeted drug delivery and cellular penetration. Catalytic propulsion mechanisms are limiting, however, with fuel requirements and specialized fluid properties being necessary to achieve propulsion. We have improved the dynamic propulsion of catalytic Janus particles by functionalizing flagellar filaments to one of their hemispheres. Flagellated Janus particles, torqued by rotating magnetic fields, swim along their rotation axis using the explicit chirality and flexibility of flagella, mimicking flagellar rotation of live bacteria. Depending on the working fluid, flagellated Janus particles can propel using either catalytic or swimming propulsion. We demonstrate experimentally that flagellated Janus particles behave predictably under the two actuation modes and can precisely follow trajectories under closed-loop feedback control. Flagellated Janus particles were demonstrated to swim in both Newtonian and shear-thickening fluids. These are the first Janus particles developed that can be propelled interchangeably between catalytic and flagellar swimming propulsion, allowing two distinct propulsion mechanisms for future use within in vivo operations.

Spontaneous symmetry breaking propulsion of chemically coated magnetic microparticles

“…For the experiments presented in this paper four different surface coatings were explored including: streptavidin with no biotinylated compounds, streptavidin combined with biotin (B4501, Sigma Aldrich), streptavidin combined with biotinylated polyethylene glycol amine (Biotin-PEG3-amine, Broadpharm), and streptavidin combined with biotin chitosan (CH-Biotin-2k, HAworks, USA, also known as 'chitosan biotin' in literature). Avidin coated particles were explored thoroughly in previous work 5 with the re-experiments performed here for comparative and validation purposes. The streptavidin–biotin coating was explored as a secondary control group to understand how a biotin surface coating by itself, without any complex molecules attached, could potentially impact propulsion behavior.…”

“…To circumvent low Reynolds number physics 1 , a variety of microrobots have been developed to produce non-reciprocal motion, including helix based microrobots that take advantage of chiral geometry to propel 2 and flexible microrobots that deform their bodies to create translational motion 3 , 4 . Additionally, Janus particles have been developed to propel through bulk fluid using chemical decomposition 5 and self-generated thermal gradients 6 , 7 . These propulsion methods are effective and situationally necessary, but come with the cost of complexity and often require expensive fabrication steps 8 .…”

“…The original investigation was restricted to microparticles coated with a streptavidin chemical functionalization (avidin) 5 . Avidin is known to interact with biotin and create one of the strongest non-covalent bonds found in nature 18 , making it highly desirable in medicine and nano-technology applications 19 .…”

Biohybrid Flexible Sperm-like Microrobot for Targeted Chemo-Photothermal Therapy

“…Recently, some research has been conducted to fabricate sperm-shaped flexible micro/nanorobots using living motile sperms as actuators or dead sperms as biotemplates. , However, inherent limits exist considering scalable fabrication, structure homogeneity, and performance robustness for practical applications. To mimic morphological structure and swimming mechanism of sperms, tremendous efforts were also made to fabricate artificial flexible micro/nanorobots with head-to-tail constructions. − These platforms were simply developed for biomimetic analysis of undulating propulsion, yet, to the best of our knowledge, drug delivery feasibility using head-to-tail flexible microrobots has not been verified. Hence, it is imperative to fabricate microrobots with flexible sperm-like structures and tackle the challenge to endow them with superior versatile performances toward targeted drug delivery.…”

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

“…[1][2][3][4] Emerging techniques for microswimmer actuation include magnetic actuation, thermal actuation, light, and ultrasound, as well as nanowires and Janus particles that are catalytically driven. [5][6][7] Magnetic actuation is a highly promising technique that offers remote, engineless, and fuel-free actuation. While the conventional techniques rely on magnetic fields with a strong gradient to generate force to remotely steer magnetic micro/nanoparticles, [8,9] alternative methods rely on relatively weak uniform rotating magnetic fields that apply torque on specially shaped magnetic microswimmers resulting in their rotation and linear motion owing to rotation-translation coupling.…”