Direct Detection of Redox Reactions of Sulfur-containing Compounds on Ferrite Nanoparticle (FP) Surface

Abstract

Direct observation of sulfur sites for sulfur-containing compounds (cysteine and its oxidative derivatives) on ferrite nanoparticles (FP) was performed by X-ray adsorption near edge structure (XANES) measurements. XANES spectra of cysteine derivatives conjugated with FP indicated that redox reactions occurred on the FP surface. Cysteine was completely oxidized to cystine and cysteinesulfinic acid and cysteic acid were partially reduced. These studies revealed that the FP surface should possess both an oxidation and reduction reactive center for sulfur-containing functional groups.

A two-step ligand exchange reaction generates highly water-dispersed magnetic nanoparticles for biomedical applications

“…The XANES spectrum of the a-MCA-MNPs showed strong peaks from the thiol group in a-MCA, suggesting that a-MCA adsorbed onto the MNP. 13 The resulting citrate-MNPs were the most highly dispersed in water by utilizing TMA as a temporary coating agent (Table 1).…”

A novel strategy for surface modification of superparamagnetic iron oxide nanoparticles for lung cancer imaging

“…14,15 Third, the PEG-Cys design has resulted in stable ligand conjugation on the SPIO surface, which helped achieve the a v b 6 -specific targeting of lung cancer cells. The bidentate chelation 21,22 and possible disulfide crosslinking [23][24][25] at the SPIO surface provide the thermodynamic driving force for the stable surface attachment of biological molecules. Similarly, Sun and coworkers have also utilized a bidentate strategy with 4-methylcatechol to achieve stable surface functionalization of SPIO particles.…”

“…The thiol and carboxylate groups on Cys can form bi-dentate binding to the Fe ions on the SPIO surface. 21,22 Furthermore, oxidation of thiol groups can lead to crosslinked disulfide between Cys residues on the SPIO surface, [23][24][25] which can further increase the stability of ligand functionalization.…”

Nanostructured Spinel Ferrites: Synthesis, Functionalization, Nanomagnetism and Environmental Applications

“…In the case of surface thiol-decorated nanostructures, special care must be taken, since free thiol groups are prone to be oxidized during the synthetic procedures. For example, several papers have reported the oxidation of DMSA and cysteine to disulfide and sulfoxide compounds in the presence of Fe 3 O 4 NPs [24,[127][128][129]; these undesirable processes not only reduce the effective amount of -SH groups but also could alter magnetite phase. To overcome this drawback, Maurizi et al [130] grafted PEG chains onto the oxide surface as steric barriers in order to avoid the formation of intermolecular disulfide bridges between adjacent DMSA molecules.…”