The Aggregation of Aβ42 Induced by Nano Copper and the Antagonistic Action of Polysaccharides

The toxic effect of A beta(42) induced by copper nanoparticle (Cu NPs) was studied by atomic force microscopy (AFM), circular dichroism (CD) spectroscopy, and Thioflavin T (ThT) fluorescence technique. Five hundred nanometers of copper nanoparticle capped with polyvinylpyrrolidone (PVP) was used to evaluate the aggregation and fibrils of A beta(42). The morphologies of A beta(42) incubated in the presence of Cu NPs changed gradually. The aggregation and fibrils were observed in AFM images. However, in the presence of polysaccharides, the Cu NPs-induced fibrillation of A beta(42) was inhibited. Interestingly, the formed Cu NPs-polysaccharides complexes can even remodel the preformed A beta(42) fibrils into the low neurotoxic amorphous aggregates, which were maybe ascribed to the higher affinity of polysaccharides for A beta(42) than Cu NPs. Besides, it was found that the binding constant of Cu NPs to A beta(42) is smaller than that of polysaccharides. The relationship among polysaccharides, copper nanoparticle, and A beta(42) morphologies and its neurotoxicity were discussed, and the binding force was analyzed.