Browsing by Author "Schweikert, Michael"

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Open Access
Covalent incorporation of tobacco mosaic virus increases the stiffness of poly(ethylene glycol) diacrylate hydrogels
(2018) Southan, Alexander; Lang, Tina; Schweikert, Michael; Tovar, Günter E. M.; Wege, Christina; Eiben, Sabine
Hydrogels are versatile materials, finding applications as adsorbers, supports for biosensors and biocatalysts or as scaffolds for tissue engineering. A frequently used building block for chemically cross-linked hydrogels is poly(ethylene glycol) diacrylate (PEG-DA). However, after curing, PEG-DA hydrogels cannot be functionalized easily. In this contribution, the stiff, rod-like tobacco mosaic virus (TMV) is investigated as a functional additive to PEG-DA hydrogels. TMV consists of more than 2000 identical coat proteins and can therefore present more than 2000 functional sites per TMV available for coupling, and thus has been used as a template or building block for nano-scaled hybrid materials for many years. Here, PEG-DA (Mn = 700 g/mol) hydrogels are combined with a thiol-group presenting TMV mutant (TMVCys). By covalent coupling of TMVCys into the hydrogel matrix via the thiol-Michael reaction, the storage modulus of the hydrogels is increased compared to pure PEG-DA hydrogels and to hydrogels containing wildtype TMV (wt-TMV) which is not coupled covalently into the hydrogel matrix. In contrast, the swelling behaviour of the hydrogels is not altered by TMVCys or wt-TMV. Transmission electron microscopy reveals that the TMV particles are well dispersed in the hydrogels without any large aggregates. These findings give rise to the conclusion that well-defined hydrogels were obtained which offer the possibility to use the incorporated TMV as multivalent carrier templates e.g. for enzymes in future studies.
Open Access
Genesis of amorphous calcium carbonate containing alveolar plates in the ciliate Coleps hirtus (Ciliophora, Prostomatea)
(2013) Lemloh, Marie-Louise; Marin, Frédéric; Herbst, Frédéric; Plasseraud, Laurent; Schweikert, Michael; Baier, Johannes; Bill, Joachim; Brümmer, Franz
Open Access
Intracellular bioaccumulation of the rare earth element Gadolinium in ciliate cells resulting in biogenic particle formation and excretion
(2023) Kohl, Jana; Schweikert, Michael; Klaas, Norbert; Lemloh, Marie-Louise
Ciliates are abundant unicellular organisms capable of resisting high concentrations of metal ions in the environment caused by various anthropogenic activities. Understanding the cellular pathways involved in resistance to and detoxification of elements is required to predict the impact of ciliates on environmental element cycles. Here, we investigated the so far unknown process of tolerance, cellular uptake and bioaccumulation of the emerging rare earth element gadolinium (Gd) in the common ciliate Tetrahymena pyriformis. Gd treatment results in the intracellular formation and excretion of biogenic Gd-containing particles. This cellular process effectively removes dissolved Gd from the organic growth medium by 53.37% within 72 h. Based on light and electron microscopic observations, we postulate a detoxification pathway: Cells take up toxic Gd 3+ ions from the medium by endocytosis, process them into stable Gd-containing particles within food vacuoles, and exocytose them. Stable biogenic particles can be isolated, which are relatively homogeneous and have a diameter of about 3 µm. They consist of the elements Gd, C, O, P, Na, Mg, K, and Ca. These findings broaden the view of metal ion accumulation by protists and are of relevance to understand environmental elemental cycles and may inspire approaches for metal recovery or bioremediation.
Open Access
Unicellular organisms with versatile solutions at the micro‐scale : functional materials and principles in ciliates
(2023) Dörr, Lennart; Kohl, Jana; Schweikert, Michael; Lemloh, Marie‐Louise
Nature's diversity offers an abundance of promising solutions for novel bioinspired functional materials and systems. In particular, single‐celled organisms exhibit solutions and material properties that are realized at the nano‐ and micro‐scales. Ciliates are ubiquitous unicellular eukaryotes that are well‐adapted to a wide range of environmental conditions. They have developed a large variety of interesting and highly specialized characteristics with unique properties and design. In this review, the background of selected ciliate characteristics is highlighted with respect to material properties and structure‐function relationships. Hierarchically complex mineralized structures, highly efficient sensors for movement and protection, shape‐memory structures, as well as survival and detoxification strategies are to be emphasized. Proposed future bioinspired applications of these properties of ciliates expand the possibilities to more sustainable materials and development processes.