Figure 6. A) Demonstration of an immotile sperm cell's pickup using a helical microswimmer and its delivery to the oocyte for fertilization in four steps: i) coupling of sperm cell and magnetic spiral, ii) its transport, iii) oocyte membrane approach and contact, iv) release. Reproduced with permission. [8]

Fine-needle aspiration cytology is a minimally invasive diagnostic strategy. However, collected specimens have to undergo a series of complex preparation steps, thus limiting the use of fine-needle aspiration cytology as a diagnostic approach for cytopathologists. In this study, we propose a cytology approach, easily adaptable to the conventional one, by employing plasmonic biomarkers (gold (red_scattering) , silver/gold (blue_scattering) , and silver/gold (green_scattering) nanoparticles), each having a well-defined optical feature. Plasmonic nanoparticles, incubated with the suspension cells, are fully visible and differentiable on the cell membranes under the darkfield lateral RGB (red−green−blue) side-illumination microscopy. The postfabrication of plasmonic nanoparticles by the conjugation of a specific antibody (antihuman epidermal growth factor receptor 2, HER2) directly allows to visualize the selectively recognized antigens of the suspension cells (MDA-MB-453 ++HER2 and Jurkat −HER2 ) in cocultures and individual cultures by using the side-illumination compared to the conventional dark-field visualization protocol. We also incubate two cancer cell lines (trypsinized MDA-MB-231 ++CD44 and MDA-MB-453 ++HER2 ) with anti-CD44 and anti-HER2 functionalized plasmonic nanoparticles, and nanoimmunoplasmonic and immunofluorescence assays show a good agreement with each other for the recognition of expressed antigens (CD44 and HER2). Our results demonstrate a remarkable potential of plasmonic nanoparticles for a simple and rapid examination of small population of cells from collected specimens by using nanoimmunoplasmonic approach and the sideillumination microscopy.

The ability of artificial microswimmers to respond to external stimuli and the mechanistical details of their origins belong to the most disputed challenges in interdisciplinary science. Therein, the creation of chemical gradients is technically challenging, because they quickly level out due to diffusion. Inspired by pivotal stopped flow experiments in chemical kinetics, we show that microfluidics gradient generation combined with a pressure feedback loop for precisely controlling the stop of the flows, can enable us to study mechanistical details of chemotaxis of artificial Janus micromotors, based on a catalytic reaction. We find that these copper Janus particles display a chemotactic motion along the concentration gradient in both, positive and negative direction and we demonstrate the mechanical reaction of the particles to unbalanced drag forces, explaining this behaviour.

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...