Adam Schröfel

Silica-coated manganite and Mn-based ferrite nanoparticles: a comparative study focused on cytotoxicity

Magnetic oxide nanoparticles provide a fascinating tool for biological research and medicine, serving as contrast agents, magnetic carriers, and core materials of theranostic systems. Although the applications rely mostly on iron oxides, more complex oxides such as perovskite manganites may provide a much better magnetic performance. To assess the risk of their potential use, in vitro toxicity of manganite nanoparticles was thoroughly analysed and compared with another prospective system of Mn–Zn ferrite nanoparticles. Magnetic nanoparticles of La0.63Sr0.37MnO3 manganite were prepared by two distinct methods, namely the molten salt synthesis and the traditional sol–gel route, whereas nanoparticles of Mn0.61Zn0.42Fe1.97O4 ferrite, selected as a comparative material, were synthesized by a new procedure under hydrothermal conditions. Magnetic cores were coated with silica and, moreover, several samples of manganite nanoparticles with different thicknesses of silica shell were prepared. The size-fractionated and purified products were analysed using transmission electron microscopy, dynamic light scattering, measurement of the zeta-potential dependence on pH, IR spectroscopy, and SQUID magnetometry. The silica-coated products with accurately determined concentration by atomic absorption spectroscopy were subjected to a robust evaluation of their cytotoxicity by four different methods, including detailed analysis of the concentration dependence of toxicity, analysis of apoptosis, and experiments on three different cell lines. The results, comparing two manganese-containing systems, clearly indicated superior properties of the Mn–Zn ferrite, whose silica-coated nanoparticles show very limited toxic effects and thus constitute a promising material for bioapplications.

Reproduction of the FC/DFC units in nucleoli

ABSTRACT The essential structural components of the nucleoli, Fibrillar Centers (FC) and Dense Fibrillar Components (DFC), together compose FC/DFC units, loci of rDNA transcription and early RNA processing. In the present study we followed cell cycle related changes of these units in 2 human sarcoma derived cell lines with stable expression of RFP-PCNA (the sliding clamp protein) and GFP-RPA43 (a subunit of RNA polymerase I, pol I) or GFP-fibrillarin. Correlative light and electron microscopy analysis showed that the pol I and fibrillarin positive nucleolar beads correspond to individual FC/DFC units. In vivo observations showed that at early S phase, when transcriptionally active ribosomal genes were replicated, the number of the units in each cell increased by 60–80%. During that period the units transiently lost pol I, but not fibrillarin. Then, until the end of interphase, number of the units did not change, and their duplication was completed only after the cell division, by mid G1 phase. This peculiar mode of reproduction suggests that a considerable subset of ribosomal genes remain transcriptionally silent from mid S phase to mitosis, but become again active in the postmitotic daughter cells.

Biosynthesis of Metallic Nanoparticles and Their Applications

Biosynthesis and biofabrication of the metallic NPs have became an important approach to NP preparation. They are not only equal with the chemical or physical methods, but also offer quite a few assets compared to classical tacks. In this review, we present comprehensive overview of existing published records, which include clear and realistic application of biosynthesized metallic NPs. Our survey covers NP utilization from biosorption and catalysis to medicinal and sensing applications. Moreover, we add current review references and comparison (or synergy) with chemical and physical methods.

Adaptation of Acidithiobacillus bacteria to metallurgical wastes and its potential environmental risks

Metallurgical wastes – oxygen converter sludge, dust from cast iron production, lead matte, and slag from recycling of used lead batteries – were treated with Acidithiobacillus bacteria. Bacterial activity and adaptability on waste and some waste mixtures were investigated. Acidithiobacillus bacteria may easily attack oxygen converter sludge, lead matte and slag and affect the mobility of metals. Cast iron dust is not a suitable substrate for applied bacteria due to the absence of reduced sulfur and reduced iron in its mineralogical composition. Nevertheless, the pure culture was able to adapt to the mixture of this waste with slag. Disposal of these metallurgical wastes deserves special attention due to potential attack by microorganisms and consequent pH changes. According to subsequent release of hazardous substances to the environment, this phenomenon can lead to evident environmental risks.

Erratum to: Antimicrobial bionanocomposite–from precursors to the functional material in one simple step

In the published manuscript http://dx.doi.org/10.1007 /s11051-016-3664-y, the minimal inhibitory concentration (MIC) value for the monitored composites is incorrectly stated: 0.014 mg/ml is the stated value while the correct value is 0.14 mg/ml. The incorrect value does not influence the general concept of the article, its other results or its conclusions, nor it demands an in-depth revision of the published text. J Nanopart Res (2017) 19: 244 DOI 10.1007/s11051-017-3938-z

Gold Nanoparticles for High Resolution Imaging in Modern Immunocytochemistry

This perspective presents the possibilities for utilization of gold nanoparticles in immunocytochemistry. The unique combination of gold nanoparticle properties is just beginning to be fully recognized for the range of diagnostic and therapeutic applications. The current findings from bionanotechnology and emerging cryo-electron microscopy techniques can lead to novel perspectives for targeted delivery of gold conjugates into cells and tissues. The chapter offers a survey of modern electron microscopy methods with a special focus on immunolabeling. We also discuss the impact of gold nanoparticles on cellular systems and the potential possibilities for their targeted delivery into cells and tissues.