Gelatine-Coated Carbonyl Iron Particles and Their Utilization in Magnetorheological Suspensions

This study demonstrates the formation of biocompatible magnetic particles into organized structures upon the application of an external magnetic field. The capability to create the structures was examined in silicone-oil suspensions and in a gelatine solution, which is commonly used as a blood plasma expander. Firstly, the carbonyl iron particles were successfully coated with gelatine, mixed with a liquid medium in order to form a magnetorheological suspension, and subsequently the possibility of controlling their rheological parameters via a magnetic field was observed using a rotational rheometer with an external magnetic cell. Scanning electron microscopy, infrared spectroscopy, and thermogravimetric analysis confirmed the successful coating process. The prepared magnetorheological suspensions exhibited a transition from pseudoplastic to Bingham behavior, which confirms their capability to create chain-like structures upon application of a magnetic field, which thus prevents the liquid medium from flowing. The observed dynamic yield stresses were calculated using Robertson–Stiff model, which fit the flow curves of the prepared magnetorheological suspensions well

Isolation and Thermal Stabilization of Bacteriocin Nisin Derived from Whey for Antimicrobial Modifications of Polymers

This work describes novel alternative for extraction of bacteriocin nisin from a whey fermentation media and its stabilization by using polyethylene glycol as matrix with high practical applicability. This product was compared with commercially available nisin product stabilized by sodium chloride and nisin extracted and stabilized by using ammonium sulfate and polysorbate 80. The stability of samples was tested by means of long-term storage at −18, 4, 25, and 55°C up to 165 days. The nisin content in the samples was determined by high-performance liquid chromatography and electrophoresis. In addition, effect of whey fortification with lactose on nisin production and antibacterial activity studied against Staphylococcus aureus was tested. Results show that stabilization by polyethylene glycol provides enhanced nisin activity at 55°C after 14 days and long-term stability at 25°C with keeping antibacterial activity

Effect of polyethylene glycol plasticizer on long-term antibacterial activity and the release profile of bacteriocin nisin from polylactide blends

This work describes the synergetic effect of polyethylene glycol (PEG) in polylactide (PLA) blends, wherein the polyether acts as both the plasticizer and functional additive, ensuring the long-term antimicrobial activity of bacteriocin nisin. Two types of PEG with the molecular weights of 1000 and 6000 g.mol−1 (20 wt.%) were used to plasticize the PLA blends. The aforementioned bacteriocin nisin, at concentrations ranging between 0.02 and 0.15 wt.% (8000-60 000 IU.g−1), was incorporated into the samples by the solvent cast technique. The effect of various PEG on the structural, mechanical, and thermal properties of the PLA-based blends were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy, stress-strain analysis, differential scanning calorimetry, and dynamic mechanical analysis, respectively. The antibacterial activity of the samples was detected by the agar diffusion technique against Micrococcus luteus. Furthermore, the antibacterial properties of the samples were tested according the ISO 22196 standard against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus, Listeria monocytogenes) bacterial strains. The nisin was detected by high performance liquid chromatography, the device having been equipped with a UV/vis detector. The results show that the PEG, besides its plasticizing effect, significantly enhances the release profile and sustains long-term antibacterial activity of nisin in a PLA matrix. Copyright © 2018 John Wiley & Sons, Ltd.LO1504; QJ1310254, MZe, Ministerstvo Zemědělství; IGA/ CPS/2018/003; LO1504; QJ1310254, MZe, Ministerstvo ZemědělstvíInternal Grant Agency of the Tomas Bata University in Zlin [IGA/CPS/2018/003]; Ministry of Agriculture of the Czech Republic [QJ1310254]; Ministry of Education, Youth, and Sports of the Czech Republic [LO1504