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In this work, new MxOy/fucoidan hybrid systems were fabricated and applied in lipase immobilization. Magnesium (MgO) and zirconium (ZrO2) oxides were used as MxOy inorganic matrices. In the first step, the proposed oxides were functionalized with fucoidan from Fucus vesiculosus (Fuc). The obtained MgO/Fuc and ZrO2/Fuc hybrids were characterized by means of spectroscopic analyses, including Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and nuclear magnetic resonance. Additionally, thermogravimetric analysis was performed to determine the thermal stability of the hybrids. Based on the results, the mechanism of interaction between the oxide supports and fucoidan was also determined. Furthermore, the fabricated MxOy/fucoidan hybrid materials were used as supports for the immobilization of lipase from Aspergillus niger, and a model reaction (transformation of p-nitrophenyl palmitate to p-nitrophenol) was performed to determine the catalytic activity of the proposed biocatalytic system. In that reaction, the immobilized lipase exhibited high apparent and specific activity (145.5 U/gcatalyst and 1.58 U/mgenzyme for lipase immobilized on MgO/Fuc; 144.0 U/gcatalyst and 2.03 U/mgenzyme for lipase immobilized on ZrO2/Fuc). The immobilization efficiency was also confirmed using spectroscopic analyses (FTIR and XPS) and confocal microscopy.

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Biotechnological use of probiotic microorganisms involves providing them with appropriate conditions for growth, but also protection against environmental changes caused by an exchange of the medium, isolation of metabolites, etc. Therefore, the research on effective immobilization of probiotic microorganisms should be focused in this direction. The present study aimed to evaluate the effectiveness of an innovative hybrid immobilization system based on electrospun nanofibers and alginate hydrogel. The analyses carried out included the study of properties of the initial components, the evaluation of the degree and durability of cell immobilization in the final material, and their survival under stress conditions. Effective binding of microorganisms to the hydrogel and nanofibers was confirmed, and the collected results proved that the proposed biocomposite is an efficient method of cell protection. In addition, it was shown that immobilization on electrospun nanofibers leads to the preservation of the highest cell activity and the least cell growth restriction as compared to free or lyophilized cells only. The completed research opens new perspectives for the effective immobilization of microorganisms of significant economic importance.

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Correction for 'The influence of diameter of multiwalled carbon nanotubes on mechanical, optical and electrical properties of Langmuir-Schaefer films' by Karol Rytel et al., Phys. Chem. Chem. Phys., 2020, DOI: .

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In this paper results of a study of mechanical, optical and electrical properties of thin films made of multiwall carbon nanotubes (MWCNT) of various types were reported. The MWCNT films were obtained on quartz substrates using the Langmuir-Schaefer (LS) method. A gradual increase in transmittance was recorded with decreasing diameters of MWCNT used. Moreover, a blue shift of the π-plasmon band position was observed with increasing MWCNT diameter. In all tested films, anisotropy of electrical surface resistivity was revealed, which was more pronounced for MWCNT of low diameters, except for the MWCNT sample of the smallest diameters. Results of oscillatory barrier measurements of various MWCNT films at the air water interface were used to calculate the complex compression and shear moduli. It is worth emphasizing that the values of these moduli were obtained for the first time for carbon nanotubes films. Moreover, the obtained results allowed identification of the main factor blocking the alignment process, which turned out to be the shear loss tangent.

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Novel electrospun poly(methyl methacrylate)/polyaniline electrospun fibres were produced, characterised, modified, and used as a support for laccase immobilisation by two methods: adsorption and covalent binding. Effective deposition of laccase by both methods was confirmed by FTIR and CLSM results. Nevertheless, the main objective of the study was to select the most favourable immobilisation conditions and prepare heterogeneous biocatalysts with the best possible catalytic properties. The highest relative activity of enzymes immobilised by adsorption and covalent binding were obtained after 1 h of immobilisation using laccase solution at a concentration of 1 mg/mL, at pH 5 and 25 °C. It was found that the immobilised enzymes, which were present in amounts of 110 mg/g and 185 mg/g for systems with adsorbed and covalently bonded laccase respectively, exhibited slightly lower substrate affinity, and in consequence also a lower maximum reaction rate, than the free enzyme. The stability of laccase improved significantly upon immobilisation: both heterogeneous biocatalysts retained over 80% relative activity even after 10 repeated catalytic cycles and 30 days of storage. The obtained systems were used for decolourisation of Remazol Brilliant Blue R dye from a model aqueous solution, resulting in removal efficiencies of 87% and 58% using adsorbed and covalently bonded laccase, respectively. The described approach to the removal of textile dye from model solution is significant for the sustainable and environmentally friendly decolourisation of various compounds from wastewater.

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The adsorption properties of surfactant mixtures containing two types of quaternary derivatives of lysosomotropic substances: alkyl N,N-dimethylalaninates methobromides and alkyl N,N-dimethylglycinates methobromides were studied. Quantitative and qualitative description of the adsorption process was carried out on the basis of experimentally obtained equilibrium surface tension isotherms. The results indicated that most of the systems studied revealed synergistic effect both in adsorption and wetting properties. In vitro studies on human cancer cells were undertaken and the data obtained showed that the mixtures suppressed the cancer cells' proliferation more effectively than individual components. Results of preliminary research on the interaction of catanionic mixtures with phospholipids suggested a possibility of a strong penetration of cell membranes by the mixtures investigated.

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