Using materials with properties similar to those of cells and microorganisms together with innovative fabrication methods, soft and smart microrobots can be developed, with increased adaptability and ...flexibility toward in vivo applications. These tiny robots are designed to carry out difficult tasks such as noninvasive microsurgery, diagnosis and therapy in complex environments, including viscous media and intricate channels. Moreover, the novel property of the soft materials to respond to stimuli has paved the way for the creation of reconfigurable and smart microrobots with both actuation and function (e.g., sensing, drug delivery) capabilities. This feature article aims to give an overview of the different soft and smart swimming microrobots (less than 1 mm in all dimensions), highlighting some aspects of new materials, their development and the challenges in their processing to obtain highly functional microrobots.
In this feature article, the latest developments of soft microrobots are presented. Novel materials and fabrication techniques are thoughtfully described, providing an overview of the current possibilities to build soft and smart swimming microrobots with advanced features such as reconfigurable morphologies, advanced control mechanisms, and multifunction capabilities.
In recent years, the combination of synthetic micro‐ and nanomaterials with spermatozoa as functional components has led to the development of tubular and helical spermbots – microrobotic devices ...with potential applications in the biomedical and nanotechnological field. Here, the initial advances in this field are discussed and the use of spermatozoa as functional parts in microdevices elaborated. Besides the potential uses of these hybrid robotic microswimmers, the obstacles along the way are discussed, with suggestions for solutions of the encountered challenges also given.
The initial advances in using spermatozoa as functional components in robotic microdevices are summarized giving an overview of the state‐of‐the‐art combinations of single‐spermatozoa‐carrying robotic components, as well as of their potential applications and current challenges.
Biohybrid micromotors propelled by motile cells are fascinating entities for autonomous biomedical operations on the microscale. Their operation under physiological conditions, including highly ...viscous environments, is an essential prerequisite to be translated to in vivo settings. In this work, a sperm‐driven microswimmer, referred to as a spermbot, is demonstrated to operate in oviduct fluid in vitro. The viscoelastic properties of bovine oviduct fluid (BOF), one of the fluids that sperm cells encounter on their way to the oocyte, are first characterized using passive microrheology. This allows to design an artificial oviduct fluid to match the rheological properties of oviduct fluid for further experiments. Sperm motion is analyzed and it is confirmed that kinetic parameters match in real and artificial oviduct fluids, respectively. It is demonstrated that sperm cells can efficiently couple to magnetic microtubes and propel them forward in media of different viscosities and in BOF. The flagellar beat pattern of coupled as well as of free sperm cells is investigated, revealing an alteration on the regular flagellar beat, presenting an on–off behavior caused by the additional load of the microtube. Finally, a new microcap design is proposed to improve the overall performance of the spermbot in complex biofluids.
Biohybrid micromotors consisting of a single sperm cell carrying a tubular microstructure offer an interesting approach to biomedical applications related to assisted fertilization. Their ability to move through oviduct fluid and other high viscosity media, while being guided magnetically, is demonstrated. Additionally, the effect of the cargo on the flagellar beat is investigated.
El presente trabajo tiene por objetivo reflexionar sobre la Sociología Jurídica como disciplina, a partir de sus conceptualizaciones, campos de estudio y principales enfoques teóricos. Aborda desde ...un enfoque crítico el estudio del Derecho como fenómeno social, y su comprensión desde los enfoques sociales en los que opera y de los significados que los sujetos construyen a partir de sus normas. Igualmente revisa las principales y diversas explicaciones teóricas acerca del Derecho de los clásicos autores de la Teoría Sociológica. Lejos de concluir que esta diversidad teórica es contradictoria o confusa en los análisis del Derecho y del sistema jurídico, debemos admitir que –por el contrario– la perspectiva sociológica es multiparadigmática y transitarla propone un interesante desafío.
How to Improve Spermbot Performance Magdanz, Veronika; Medina-Sánchez, Mariana; Chen, Yan ...
Advanced functional materials,
May 13, 2015, Letnik:
25, Številka:
18
Journal Article
Recenzirano
Spermbots are biocompatible hybrid machines that consist of microtubes which are propelled by single spermatozoa and have promising features for powering nano and microdevices. This article presents ...three approaches on how to improve the performance of such spermbots. First, 20 μm microtubes produce faster spermbots compared to the previously reported 50 μm long microtubes. Furthermore, biofunctionalization by microcontact printing and surface chemistry of biomolecules on the inner tube surface improve the coupling efficiency between sperm cell and microtube, and the addition of caffeine results in a speed boost of the sperm‐driven micromotor.
Improved spermbot performance is demonstrated by biofunctionalization of the inner tube surface, shorter tube design, and caffeine addition. Firstly, spermbot velocity is improved by the use of shorter microtubes; secondly, better coupling efficiency is achieved by binding of fibronectin inside the microtube; and finally, caffeine addition gives a temporary speed boost to the spermbot.
A flexible, biological field‐effect transistor (BioFET) for use in biosensing is reported. The BioFET is based on an organic thin‐film transistor (OTFT) fabricated mainly by inkjet printing and ...subsequently functionalized with antibodies for protein recognition. The BioFET is assessed for label‐free detection of a model protein, human immunoglobulin G (HIgG). It is characterized electrically to evaluate the contribution of each step in the functionalization of the OTFT and to detect the presence of the target protein. The fabrication, structure, materials optimization, electrical characteristics, and functionality of the starting OTFT and final BioFET are also discussed. Different materials are evaluated for the top insulator layer, with the aim of protecting the lower layers from the electrolyte and preserving the BioFET electrical performance.
A flexible BioFET for label‐free biosensing is reported. It is based on an inkjet‐printed organic thin‐film transistor whose insulator is functionalized with specific antibodies for protein recognition. As proof‐of‐concept, the BioFET is evaluated for quantification of human immunoglobulin G (HIgG).
An integrated system combining a magnetically‐driven micromotor and a synthetized protein‐based hyaluronic acid (HA) microflake is presented for the in situ selection and transport of multiple motile ...sperm cells (ca. 50). The system appeals for targeted sperm delivery in the reproductive system to assist fertilization or to deliver drugs. The binding mechanism between the HA microflake and sperm relies on the interactions between HA and the corresponding sperm HA receptors. Once sperm are captured within the HA microflake, the assembly is trapped and transported by a magnetically‐driven helical microcarrier. The trapping of the sperm‐microflake occurs by a local vortex induced by the microcarrier during rotation‐translation under a rotating magnetic field. After transport, the microflake is enzymatically hydrolyzed by local proteases, allowing sperm to escape and finally reach the target location. This cargo‐delivery system represents a new concept to transport not only multiple motile sperm but also other actively moving biological cargoes.
A cluster of motile and mature sperm previously immobilized on the BSA‐HA microflake is transported by a magnetically‐driven microhelix, which delivers the sperm‐loaded microflake close to the area of interest. Due to the presence of local proteases, the microflake is then hydrolyzed allowing the sperm release to finally reach the target location.
A sperm-driven micromotor is presented as a targeted drug delivery system, which is appealing to potentially treat diseases in the female reproductive tract. This system is demonstrated to be an ...efficient drug delivery vehicle by first loading a motile sperm cell with an anticancer drug (doxorubicin hydrochloride), guiding it magnetically, to an in vitro cultured tumor spheroid, and finally freeing the sperm cell to deliver the drug locally. The sperm release mechanism is designed to liberate the sperm when the biohybrid micromotor hits the tumor walls, allowing it to swim into the tumor and deliver the drug through the sperm–cancer cell membrane fusion. In our experiments, the sperm cells exhibited a high drug encapsulation capability and drug carrying stability, conveniently minimizing toxic side effects and unwanted drug accumulation in healthy tissues. Overall, sperm cells are excellent candidates to operate in physiological environments, as they neither express pathogenic proteins nor proliferate to form undesirable colonies, unlike other cells or microorganisms. This sperm-hybrid micromotor is a biocompatible platform with potential application in gynecological healthcare, treating or detecting cancer or other diseases in the female reproductive system.
The spread of non‐indigenous and invasive seaweeds has increased worldwide, and their potential effects on native seaweeds have raised concern. Undaria pinnatifida is considered among the most ...prolific non‐indigenous species. This species has expanded rapidly in the Northeast Pacific, overlapping with native communities such as the iconic giant kelp forests (Macrocystis pyrifera). Canopy shading by giant kelp has been argued to be a limiting factor for the presence of U. pinnatifida in the understory, thus its invasiveness capacity. However, its physiological plasticity under light limitation remains unclear. In this work, we compared the physiology and growth of juvenile U. pinnatifida and M. pyrifera sporophytes transplanted to the understory of a giant kelp forest, to juveniles growing outside of the forest. Extreme low light availability compared to that outside (~0.2 and ~4.4 mol photon ⋅ m−2 ⋅ d−1, respectively) likely caused a “metabolic energy crisis” in U. pinnatifida, thus restricting its photoacclimation plasticity and nitrogen acquisition, ultimately reducing its growth. Despite M. pyrifera juveniles showing photoacclimatory responses (e.g., increases in photosynthetic efficiency and lower compensation irradiance, Ec), their physiological/vegetative status deteriorated similarly to U. pinnatifida, which explains the low recruitment inside the forest. Generally, our results revealed the ecophysiological basis behind the limited growth and survival of juvenile U. pinnatifida sporophytes in the understory.
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