Adsorption of cysteine on hematite, magnetite and ferrihydrite: FT-IR, Mössbauer, EPR spectroscopy and X-ray diffractometry studies

Abstract

In the present paper, the adsorption of cysteine on hematite, magnetite and ferrihydrite was studied using FT-IR, electron paramagnetic resonance (EPR), Mössbauer spectroscopy and X-ray diffractometry. Cysteine was dissolved in artificial seawater (two different pHs) which contains the major constituents. There were two main findings described in this paper. First, after the cysteine adsorption, the FT-IR spectroscopy and X-ray diffractometry data showed the formation of cystine. Second, the Mössbauer spectroscopy did not show any increase in the amount of Fe(2+) as expected due the oxidation of cysteine to cystine. An explanation could be that Fe(2+) was oxidized by the oxygen present in the seawater or there occurred a reduction of cystine by Fe(2+) generating cysteine and Fe(3+). The specific surface area and pH at point of zero charge of the iron oxides were influenced by adsorption of cysteine. When compared to other iron oxides, ferrihydrite adsorbed significantly (p < 0.05) more cysteine. The pH has a significant (p < 0.05) effect only on cysteine adsorption on hematite. The FT-IR spectroscopy results showed that cystine remains adsorbed on the surface of the iron oxides even after being mixed with KCl and the amine and carboxylic groups are involved in this interaction. X-ray diffractometry showed no changes on iron oxides mineralogy and the following precipitated substances were found along with the iron oxides after drying the samples: cysteine, cystine and seawater salts. The EPR spectroscopy showed that cysteine interacts with iron oxides, changing the relative amounts of iron oxides and hydroxide.

Hydrophobic Forces Are Relevant to Bacteria-Nanoparticle Interactions: Pseudomonas putida Capture Efficiency by Using Arginine, Cysteine or Oxalate Wrapped Magnetic Nanoparticles

“…This is in agreement with the fact that if ligand density increases, the magnetization decreases. [21] and other applications [27]. An interesting feature observed in Figure 4 is that when NPs wrapped with a small molecule (as oxalate) are replaced by bigger ones (as the amino acids), magnetization increases, although a magnetization decrease was expected (same magnetic core, more non-magnetic organic wrap).…”

“…For all NPs synthetized in this study, we detected stretching signals corresponding to carboxyl group vibrations. In particular, C=O stretching and C-O-H in plane bending signals corresponding to the carboxylic acid can be observed at values closed to 1600 cm −1 and 1400 cm −1 , respectively [18,24,27]. We found a carbonyl signal at 1634 cm −1 for Fe3O4@Oxa, 1624 cm −1 for Fe3O4@Cys and 1653 cm −1 for Fe3O4@Arg; we also found C-O-H in plane bending signals at 1403 cm −1 for Fe3O4@Oxa, 1398 cm −1 for Fe3O4@Arg and 1408 cm −1 for Fe3O4@Cys.…”

“…For all NPs synthetized in this study, we detected stretching signals corresponding to carboxyl group vibrations. In particular, C=O stretching and C-O-H in plane bending signals corresponding to the carboxylic acid can be observed at values closed to 1600 cm −1 and 1400 cm −1 , respectively [18,24,27]. We found a carbonyl signal at 1634 cm −1 for Fe 3 2− equal to 2:1:1 was used in the first synthesis step, but when molar ratio was 2:1:0.1, as Tie et al used [24], these signals did not appear ( Figure S2).…”

Adsorption of Adenine, Cytosine, Thymine, and Uracil on Sulfide-Modified Montmorillonite: FT-IR, Mössbauer and EPR Spectroscopy and X-Ray Diffractometry Studies

“…In general, when nucleic acid bases were adsorbed on clays an increase on the intensity of this line was observed (Table 3). However, an inverse trend was observed when cysteine was adsorbed on clays and on iron oxides Vieira et al 2011). The resonance line g=4.1 could be due to Fe 3+ with rhombic symmetry as well as the interaction of Fe 3+ with organic matter (Guskos et al 2002;Carbone et al 2005;Mota et al 2009).…”

Novel nanostructured hematite–spongin composite developed using an extreme biomimetic approach

“…49,50,64 Raman spectroscopy Raman spectroscopy, as a fast and nondestructive analytical technique, was used to determine qualitative properties of the crystalline product. The analysis was performed for the a-Fe 2 O 3 -spongin composite and compared with hematite standard as well as unmodied spongin bers (Fig.…”