Nanoparticles Stymie Peptide Aggregation

Although scientists have shown that some nanoparticles trigger the aggregation of amyloid-β peptides through nucleation, two research groups report independently that smaller-sized inorganic part­icles inhibit the process, which is associated with neurodegenerative diseases such as Alz­heimer’s. Because nanoparticles can cross the blood-brain barrier, says Nicholas A. Kotov of the University of Michigan, who leads one of the groups, these findings could drive the design of particles that protect against neurodegeneration. Kotov’s team demonstrated that tetrahedral CdTe particles stabilized with thioglycolic acid strongly disrupt amyloid-β aggregation (Angew. Chem. Int. Ed., DOI: 10.1002/anie.201007824). Using microscopy and spectroscopy, the researchers determined that the 3.5-nm-diameter particles, which are about the same size as folded peptide strands, act by immobilizing aggregation intermediates mainly via van der Waals for­ces. Xiaogang Qu of China’s Changchun Institute of Applied Chemistry and coworkers similarly found that the polyoxometalate K₈[P₂CoW₁₇O₆₁] halts fibril formation in amyloid-β peptides (Angew. Chem. Int. Ed., DOI: 10.1002/anie.201007067). Peptide digestion experiments revealed that the 1.5-nm-diameter K₈[P₂CoW₁₇O₆₁] particles bind tightly to a positively charged tract of amyloid-β, likely preventing aggregation electrostatically.