Ability of Silver Nanoparticles to Inhibit Amyloid Aggregation and their Potential Role in Prevention of Alzheimer?s Disease

The aggregation of misfolded proteins leads to various cellular malfunctions and disorders such as Alzheimer’s disease. The conventional treatments of such diseases often fail due to their inability to cross the blood-brain barrier. The ability of nanoparticles to influence protein folding and aggregation and, as a result, their potential therapeutic effect in diseases involving protein aggregation, sounds promising. The objective of this study was to determine the effect of silver nanoparticles (AgNPs) on the amyloid aggregation of Hen Egg White Lysozyme (HEWL).
Material and Lysozyme was dissolved at 2 mg/mL in a 50 mM glycine buffer (pH 2.5) and incubated at 57 °C while being stirred gently with Teflon magnetic bar; the result was conversion of lysozyme to amyloid. The effect of the particles was assessed using different technics: Thioflavin T (ThT), Congo Red, atomic force microscopy (AFM) and Toxic test (MTT). Data were analyzed using SPSS 16, the statistical test being the independent t-test. Incubation of lysozyme with AgNPs at a concentration of 3-60 mcg/L could inhibit the HEWL fibrillation (p<0.05). Surprisingly, the lowest concentration (3 mcg/L) was found to be the most effective; at this concentration, the lag time (nucleation phase) became longer and the fibrillation phase considerably shortened. In addition, the cytotoxicity of the aggregated amyloids in the cell culture decreased. Based on the findings, it is concluded that silver nanoparticle surfaces can actas nano-chaperones and inhibit HEWL fibrillation; thus, they can potentially be used in the treatment of Alzheimer’s disease