Pathogenesis of amyloid-related diseases is related to nonnative folding of proteins with the formation of insoluble deposits in the extracellular space of various tissues. Having the unique properties of small size, large surface area, biodegradability, and relative nontoxicity, magnetic nanoparticles have drawn a lot of attention in biomedical applications. Herein, we demonstrate the effect of bare and differently functionalized magnetic MnFe2O4 nanoparticles on fibrillation of human serum albumin in vitro. The process has been monitored using Thioflavin T fluorescence, Congo red binding assay, circular dichroism, fluorescence microscopy, and transmission electron microscopy. From our experimental results, amine functionalized MnFe2O4 nanoparticles are found to inhibit formation of fibrils more effectively than bare ones, while carboxylated nanoparticles do not have a significant effect on fibrillation. This study has explored the prospects of using specific magnetic nanoparticles with appropriate modification to control self-assembly of proteins and may act as a precursor in therapeutic applications.

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In order to demonstrate the influence of the surface chirality of the nanoparticles on amyloid fibrillation, the inhibiting effectiveness of the chiral gold nanoparticles, synthesized using the two enantiomeric forms (i.e., d- and l-) of glutamic acid, toward the fibrillation of human serum albumin (HSA) has been investigated. Here the enantiomers of glutamic acid are used as both reducing and stabilizing/capping agents. It is found that the surface chirality is the only major difference between the d-glutamic acid mediated gold (DGAu) and l-glutamic acid mediated gold (LGAu) nanoparticles. The fibrillation process has been monitored using various biophysical techniques, e.g., turbidity assay, Thioflavin T fluorescence kinetics, Congo red binding study, circular dichroism spectroscopy, fluorescence microscopy, and transmission electron microscopy. The experimental results illustrate that DGAu is more effective in inhibiting the formation of HSA fibrils than LGAu. Furthermore, the differential inhibiting effect of DGAu and LGAu toward HSA fibrillation has been described on the basis of the dissimilar interaction behavior of the nanoparticles with the HSA molecules, as revealed by the Trp fluorescence quenching, and the isothermal titration calorimetry. It is suggested that the surface chirality of the gold nanoparticles strongly influences the protein adsorption dynamics including the modes of orientation of adsorbed HSA molecules, causing the inhibition of fibrillation to different extents.

Electrostatic interaction of chitosan-based silver nanoparticles with human serum albumin leads to inhibition of fibrillogenesis.

The influence of different morphologies of nanostructures on amyloid fibrillation has been investigated by monitoring the fibrillation of human serum albumin (HSA) in the presence of rod-, sphere-, flower-, and star-shaped copper oxide (CuO) nanostructures. The different morphologies of CuO have been synthesized from an aqueous solution-based precipitation method using various organic acids, viz., acetic acid, citric acid, and tartaric acid. The fibrillation process of HSA has been examined using various biophysical techniques, e.g., Thioflavin T fluorescence, Congo red binding studies through UV spectroscopy, circular dichroism spectroscopy, and fluorescence microscopy. The monolayer protein coverage on the CuO nanostructures has been established through DLS studies, and the well-fitted Langmuir isotherm model has been used to interpret the differential adsorption behavior of HSA molecules on the CuO nanostructures. The nanostar-shaped CuO, by virtue of their higher specific surface area (94.45 m g), presence of high indexed facets {211} and high positive surface charge potential (+16.2 mV at pH 7.0) was found to show the highest adsorption of the HSA monomers and thus was more competent to inhibit the formation of HSA fibrils compared to the other nanostructures of CuO.