Conformational analysis of bovine serum albumin adsorbed on halloysite nanotubes and kaolinite: a Fourier transform infrared spectroscopy study

Abstract

Clay minerals are widely used in pharmaceutical formulations, therefore studying how they interaction with proteins is important because they can alter their biological functions. The interactions of proteins with nanostructured clays and, in general, with nanomaterials should also be studied because nanoparticles are known to interfere with protein amyloid formation, which is implicated in severe neurodegenerative diseases. Kaolinite and halloysite belong to the kaolinite group of minerals with the nominal formula Al 2 Si 2 O 5 (OH) 4 per half unit cell, however they have important structural layer stacking differences. We studied the surface interactions between clays and bovine serum albumin (BSA) by Fourier Transform Infrared Spectroscopy in order to understand the role of clay morphology on protein conformation. We show that the conformational changes of BSA depend on protein concentration and its initial structure, clay morphology and the clay/protein ratio. The surface curvature radius seems to play a key role in the final conformation. Both the curved nanoscale surface of halloysite nanotubes (HNTs) and the flat morphology of kaolinite (Kao) interfere profoundly on the a/b transitions of BSA. BSA conformation also determines the percentage of protein adsorbed on the clay surface.

Going through the wine fining: Intimate dialogue between organics and clays

“…A shift in amide I and amide II bands from 1640 cm -1 to 1643 cm -1 and from 1521 cm -1 to 1525cm -1 in Figure 4(a) were observed. This is consistent with the change in the secondary structure of the protein [22,48]. onto Mt, peaks are shifted to 178.5; 175.8 and 173.0 ppm.…”

Aquazol as a binder for retouching paints. An evaluation through analytical pyrolysis and thermal analysis

“…Alizarin based pigments, such as Garanza lake (PR83), are obtained by the precipitation of its aluminum complex, usually in the form of hydrated aluminate or hydrated silicoaluminate of calcium and/or magnesium.The TG curve of Kremer's alizarin shows a complex profile due to the mixture of kaolinite and alizarin dye (Figure 4A): a residue percentage of 43% at 900 °C is observed, attributed to the inorganic component. This is consistent with the IR spectrum of the alizarin pigment (Supplementary data,Figure S1), which corresponds to the overlap of the spectra of pure alizarin and of hydrated silicoaluminate associated with mineral kaolinite[ 43 ]. The LIBS spectra of Alizarin lake (Supplementary data,Figure S2) shows the typical lines of silicon, calcium, magnesium, aluminum (probably ascribed to the presence of kaolinite): it also highlights the typical lines of titanium, revealing that a titanium-based filler is also present.A marked dehydration is observed in the TG in the range Tamb -135 °C, with two distinct and reproducible DTG maxima at 71° and 133°C.…”

Physico–Chemical Interaction between Clay Minerals and Albumin Protein according to the Type of Clay

“…Compared with the primary and secondary structure, the tertiary structure, which determines the function of the protein by controlling the three-dimensional structure, is formed by relatively weak forces, such as van der Waals interactions, occasional disulfide bonds, etc., and thus the tertiary structure can be influenced by external chemical and physical stimuli. There have been reports that complicated denaturation phenomena of proteins upon reaction with nanoparticles can be quantitatively evaluated by the protein fluorescence quenching assay [28][29][30], although we cannot clarify the origin of denaturation with this method. In order to find biomedical applications of clays, one must evaluate how the chemical and physical properties of clays affect both the secondary structure and general 3-dimensional structure of proteins.…”

“…It is possible for clays to accommodate proteins in their intra-or inter-particular space. Tubular clays, like halloysite nanotubes (HNT), can accommodate proteins inside the tube lumen [26][27][28][29]. When proteins are incorporated into clays, there are concerns that the conformation of the protein may change, as the three-dimensional shape is strongly related to the function of the protein.…”