Instability Of Iron Research Articles

Lactoferrin as a carrier of iron: Development and physicochemical characterization

Iron deficiency is the main cause of anemia, one of the most common nutritional deficiencies affecting millions of people worldwide. In addition, iron instability, sensitivity, and intense flavor limit its use in food fortification. In this work, lactoferrin (LF) particles were developed by Nano Spray Dryer (NSD) and its capacity to be used as an iron carrier was evaluated. The effect of NSD temperature (60 °C, 80 °C, and 100 °C) and LF concentrations (10 mg mL−1, 50 mg mL−1, and 100 mg mL−1) was evaluated on the LF structure and on the production and stability of a LF-iron carrier. Results showed that the NSD is suitable for producing LF particles with diameters ranged from 38.8 nm to 4533.6 nm. Although different surface morphologies were obtained, higher protein concentrations (100 mg mL−1) produced round shape and smooth surface particles, but for lower protein concentrations (10 mg mL−1 and 50 mg mL−1) wrinkled particles and doughnut shape particles were obtained. SDS-page electrophoresis and circular dichroism (CD) for secondary structure (185–260 nm) show that the characteristics of the structures were maintained, meaning that NSD does not cause protein degradation. CD for tertiary structure (250 nm–350 nm) and fluorescence tests confirmed the interaction between LF and iron, observed by an intensity decrease and a wavelength shift in fluorescence spectra. The CD tertiary structure analysis showed higher ellipticity for the Trp peak, meaning conformational changes in the neighbor amino acids due to protein-iron interaction. Iron release experiments were performed at different pH values (2.0 and 7.4) at 37 °C aiming to understand the release mechanism in different media. Results showed that at pH 2 the iron release could be described by the linear superposition model (Radj2 = 0.9879) (explained by Fick and relaxation phenomenon) and that at pH 7.4 there is no iron release, showing that particles are stable at neutral pH. NSD is a suitable technology for producing iron-loaded protein-based carriers that could be used in food applications.

Inexpensive and robust iron-based electrode substrates for water electrolysis and energy storage

The instability of iron under anodic conditions makes iron-based electrode substrates unsuitable for alkaline electrolyzers and rechargeable alkaline batteries. Therefore, significantly more expensive substrates such as nickel foam or sintered nickel are used. Nickel adds a significant cost to electrolysis and energy storage systems. We show that iron substrates can be stabilized using a unique protective thermal coating. These coatings can also yield some of the most electrocatalytically active electrodes in addition to showing no notable change in performance even after 1500 h of anodic polarization. Besides sintered iron, low-carbon steel mesh can be stabilized similarly. Low-carbon steel protected by a thin layer of lithium-doped cobalt spinel was found to be an excellent current collector for positive nickel hydroxide electrodes in alkaline batteries. Thus, surface-modified iron substrates, 40 times less expensive than nickel, are promising for lowering the material costs of alkaline water electrolyzers and rechargeable alkaline batteries.

A new approach to the equilibrium study of iron(III) thiocyanates which accounts for the kinetic instability of the complexes particularly observable under high thiocyanate concentrations

The kinetic instability of iron(III) thiocyanate complexes in aqueous solution, evidenced by the loss of solution colour with time, has made it difficult to determine reliable equilibrium data. A technique, which measures the absorbance of these solutions as a function of time within milliseconds of mixing Fe3+ with SCN− and which extrapolates to an initial spectrum at time zero, has been designed to overcome these difficulties and is described in this paper. Two complexes, Fe(SCN)2+ and Fe(SCN)2+, have been identified upon analysing the absorbance data for thiocyanate concentrations up to 0.25M at 25°C and an ionic strength of 0.5M. Equilibrium constants, K1=(98±1)/M-1 and K2=(7±1)/M-1 have been determined and comparisons made with the literature.