Effect of Viscosity on Microswimmers: A Comparative Study

Nsamela, Audrey; Sharan, Priyanka; Garcia-Zintzun, Aidee; Heckel, Sandra; Chattopadhyay, Purnesh; Wang, Linlin; Wittmann, Martin; Gemming, Thomas; Sáenz, James; Simmchen, Juliane

doi:10.1002/cnma.202100119

Cited by 7 publications

(8 citation statements)

References 54 publications

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“…We speculate that this observation was probably related to the fact that the disassembly of the P3 L brushes was either inefficient and/or resulted in an increased local viscosity that might have impaired the locomotion of these motors (Movie S4, Supporting Information). [ 42 ]…”

Section: Resultsmentioning

confidence: 99%

pH‐Responsive Motors and their Interaction with RAW 264.7 Macrophages

Ramos-Docampo

Qian

Ade

et al. 2022

Adv Materials Inter

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sues. Exploring the benefit of motors over their passively diffusing counterparts in cell culture or in animal models attracted substantial attention in the past years. [5,6] Early examples focused on externallydriven motors that made use of physical stimuli to propel in low-density media. Recent examples include the use of nearinfrared (NIR) light-activated motors to penetrate a 3D cell tumor culture, which selectively induced cell apoptosis upon NIR irradiation or resulted in depleted amyloid aggregation. [7] Similarly, magnetically driven motors made of CaCO 3 and Fe 3 O 4 showed an increased cellular uptake since their mobility allowed for more efficient approaching of the target area. [8] The decomposition of the core particle in the acidic environment of the lysosomes assisted cargo release. In a different approach, Shen et al. employed Zn-doped iron oxide rods that swarmed and eventually spun under a rotating magnetic field, inducing cell death. [9] This effect was also assessed in vivo, where the size of tumors generated in mice decreased 4× upon magnetic therapy. Further, ultrasound-powered motors used for antigen delivery showed a 5-7-fold increase in cell penetration compared to passive particles. [10] Alternatively, motors that harvest energy from their local environment are a powerful option to design truly autonomous motors. There are examples of motors that showed locomotion in simple 2D cell models as well as more complex 3D cultures and even in animal models. Mesoporous silica particles [11] or liposomes [12,13] were chosen to assess cellular uptake in 2D cultures, showing promising results. For instance, Llopis-Lorente et al. engineered a mesoporous silica motor that moved due to the conversion of urea into ammonia and CO 2 . [14] After entrapment in the lysosomes, a 4× lower motor concentration was needed to release the same amount of cargo as their passive particle counterparts, an aspect that was attributed to the enhanced diffusion of the motors. Further, Wilson and co-workers designed a drug-loaded liposome-based motor that gained locomotion in the acidic pH generated in the surroundings of HeLa cells. [15] These motors showed a chemo tactic behavior towards acidic environments where they reached speeds up to ≈9 µm s −1 at pH 4.6.Other motors were able to penetrate 3D cell environments or tissues. For example, we showed that collagenase-propelled motors posed velocities up to 22 µm s −1 in collagen fiber networks, being eventually able to enhance penetration into bone Nano/micromotors are self-propelled particles that use external stimuli to gain locomotion outperforming Brownian motion. Here, three different polymers are employed that are conjugated to silica particles through a pH-labile linker. At slightly acidic pH, the linkers hydrolyze and release the polymeric chains, resulting in enhanced locomotion. The motors show a maximum velocity of ≈3 µm s −1 in cell media when poly(ethylene glycol) methyl ether methacrylate is asymmetrically distributed on the surface of the particles. Furthe...

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Section: Resultsmentioning

confidence: 99%

pH‐Responsive Motors and their Interaction with RAW 264.7 Macrophages

Ramos-Docampo

Qian

Ade

et al. 2022

Adv Materials Inter

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“…13 However, this elegant approach does not give realistic estimates for photoactive systems. Measurements of the displaced water volume by gas evolution can measure the specifications of colloids, 27 but have not been used on photoactive systems. To achieve a precise measurement of the O 2 generation on a defined amount of particles, we developed a Janus Au@TiO 2 colloidal monolayer with well-known dimensions (see SEM image Fig.…”

Section: Motion Mechanismsmentioning

confidence: 99%

Determination of the swimming mechanism of Au@TiO₂ active matter and implications on active–passive interactions

Wang

Simmchen

2023

Soft Matter

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“…It was found that micrometer-sized Janus particles and tubular swimmers experience drag-related speed reductions when swimming in viscous media. [64,74,75] An interesting effect, that is frequently overlooked in physical considerations, is the influence of polymers on the catalysts that create flows for propulsion, which has no direct counterpart in biological systems, but the toxicity that the polymer molecules might have on cells shows certain similarities. [64]…”

Section: Swimming In Highly Viscous Environmentsmentioning

confidence: 99%

“…[57][58][59][60][61][62][63] A first attempt to interpret this behavior by Berg and Turner ascribed this to the gel-like behavior of the network formed by the polymer chains. [58] However, depending on the specific polymer, its behaviors, and effects on the biological entities, this behavior can be weak [64] or even absent as experienced for specific smooth-swimming E. coli. [60,63] A recent work looked in very much detail at the interactions between E. coli and colloidal obstacles, concluding that it might actually be path-straightening, instead of polymer dynamics that cause the speed enhancement.…”

Section: Swimming In Highly Viscous Environmentsmentioning

confidence: 99%

Colloidal Active Matter Mimics the Behavior of Biological Microorganisms—An Overview

Nsamela

Zintzun

Montenegro‐Johnson

et al. 2022

Small

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resources from the environment into building blocks and provides energy, and the capacity to pass on some form of inheritable information to the next generation. [1] The creation of artificial life-able to replicate these behaviors-is extensively studied with droplets, vesicles, [2] and DNA nanotechnology. [3] However, these exciting approaches belong to synthetic biology and are reviewed in detail in other excellent reviews. [4] While bio-inspiration has long been a driver for game-changing developments such as airplanes, submarines, radar, and water-repelling surfaces, on the small scale we see yet relatively few such developments. [5] There are fascinating micro-organisms that have evolved over billions of years, and over the course of this process they managed to adapt in different environments. The integration of living beings into their environment is a dynamic process that requires reaction and adaptation to external conditions and stimuli; it is all the more impressive, therefore, that some bacteria have adapted to water and land, but socalled thermo-and extremophiles have even adapted to survive the harshest conditions. Potential uses for smart small scale devices are plentiful, and range from drug delivery to sensing and environmental remediation, with specific literature available on all of these. [6][7][8] The first step is often assumed to be the ability to sense certain physical or chemical changes in the surroundings, and then evaluate which condition is more favorable and adapt accordingly. Artificial micromotors mimic biological microswimmers (Figure 1) in a fully synthetic way, giving microdevices motility, previously the attribute of living systems. Due to the small scale of these devices, their sensing and signal processing capabilities are very limited; yet still, several resemblances with living microswimmers have been observed and studied, and often impressive similarities or even additional understanding can be found. The goal of this review paper is to summarize recent progress in this area, and to give insight into the physical backgrounds of such biomimetic behaviors. Comparison of Biological and Synthetic Active MatterBiological microorganisms, often referred to as "microbes," are a highly diversified collection of living entities from all three branches of the tree of life: Bacteria and Archaea, which are This article provides a review of the recent development of biomimicking behaviors in active colloids. While the behavior of biological microswimmers is undoubtedly influenced by physics, it is frequently guided and manipulated by active sensing processes. Understanding the respective influences of the surrounding environment can help to engineering the desired response also in artificial swimmers. More often than not, the achievement of biomimicking behavior requires the understanding of both biological and artificial microswimmers swimming mechanisms and the parameters inducing mechanosensory responses. The comparison of both classes of microswimmers provides with analogies in thei...

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Effect of Viscosity on Microswimmers: A Comparative Study

Cited by 7 publications

References 54 publications

pH‐Responsive Motors and their Interaction with RAW 264.7 Macrophages

pH‐Responsive Motors and their Interaction with RAW 264.7 Macrophages

Determination of the swimming mechanism of Au@TiO₂ active matter and implications on active–passive interactions

Colloidal Active Matter Mimics the Behavior of Biological Microorganisms—An Overview

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Effect of Viscosity on Microswimmers: A Comparative Study

Cited by 7 publications

References 54 publications

pH‐Responsive Motors and their Interaction with RAW 264.7 Macrophages

pH‐Responsive Motors and their Interaction with RAW 264.7 Macrophages

Determination of the swimming mechanism of Au@TiO2 active matter and implications on active–passive interactions

Colloidal Active Matter Mimics the Behavior of Biological Microorganisms—An Overview

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Product

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Determination of the swimming mechanism of Au@TiO₂ active matter and implications on active–passive interactions