Changes in the Secondary Structure and Assembly of Proteins on Fluoride Ceramic (CeF₃) Nanoparticle Surfaces

Abstract

Fluoride nanoparticles (NPs) are materials utilized in the biomedical field for applications including imaging of the brain. Their interactions with biological systems and molecules are being investigated, but the mechanism underlying these interactions remains unclear. We focused on possible changes in the secondary structure and aggregation state of proteins on the surface of NPs and investigated the principle underlying the changes using the amyloid β peptide (Aβ 16–20 ) based on infrared spectrometry. CeF 3 NPs (diameter 80 nm) were synthesized via thermal decomposition. Infrared spectrometry showed that the presence of CeF 3 NPs promotes the formation of the β-sheet structure of Aβ 16–20 . This phenomenon was attributed to the hydrophobic interaction between NPs and Aβ peptides in aqueous environments, which causes the Aβ peptides to approach each other on the NP surface and form ordered hydrogen bonds. Because of the coexisting salts on the secondary structure and assembly of Aβ peptides, the formation of the β-sheet structure of Aβ peptides on the NP surface was suppressed in the presence of NH 4 + and NO 3 – ions, suggesting the possibility that Aβ peptides were adsorbed and bound to the NP surface. The formation of the β-sheet structure of Aβ peptides was promoted in the presence of NH 4 + , whereas it was suppressed in the presence of NO 3 – because of the electrostatic interaction between the lysine residue of the Aβ peptide and the ions. Our findings will contribute to comparative studies on the effect of different NPs with different physicochemical properties on the molecular state of proteins.

Effect of CeO2 NPs on stability of regenerated silk fibroin against UV‐aging

“…With the increase of β‐sheet, the structure of the protein fiber will be more solid 37,38 . The addition of CeO 2 NPs directly increases the content of β‐sheet 39 and improves the mechanical properties of RSF fibers (Figure 4f).…”

Infrared spectroscopy analysis determining secondary structure change in albumin by cerium oxide nanoparticles

“…The potential for such conformational changes was indicated by the Raman shift in the amide I region of bovine serum albumin (BSA) interacting with zinc oxide NPs ( Žūkienė and Snitka, 2015 ). Based on the Fourier transform infrared (FT-IR) spectra of the amide I band ( Sakaguchi et al, 2022 ), we recently reported that concentrating amyloid β peptides on the NP surface may enhance the formation and stacking of their β-sheet structure. The coexistence of ions that can interact with peptides also modifies the interaction between the NPs and peptides ( Sakaguchi et al, 2022 ).…”

“…Based on the Fourier transform infrared (FT-IR) spectra of the amide I band ( Sakaguchi et al, 2022 ), we recently reported that concentrating amyloid β peptides on the NP surface may enhance the formation and stacking of their β-sheet structure. The coexistence of ions that can interact with peptides also modifies the interaction between the NPs and peptides ( Sakaguchi et al, 2022 ). Some other studies reported a potential of secondary structure (conformational) changes of albumin by metal oxide NPs such as titanium dioxide, zinc oxide, CeO 2 , ( Simón-Vázquez et al, 2014 ; Ranjan et al, 2016 ; Bukackova and Marsalek, 2020 ), and iron oxide ( Mehrabi et al, 2021 ; Nisar et al, 2022 ).…”