Fibril Growth Behavior of Amyloid beta on Polymer-Based Planar Membranes: Implications for the Entanglement and Hydration of Polymers

The design of biosensors and artificial organs using biocompatible materials with a low affinity for amyloid beta peptide (A beta) would contribute to the inhibition of fibril growth causing Alzheimer's disease. We systematically studied the amyloidogenicity of A beta on various planar membranes. The planar membranes were prepared using biocompatible polymers, viz., poly(methyl methacrylate) (PMMA), polysulfone (PSf), poly(L-lactic acid) (PLLA), and polyvinylpyrrolidone (PVP). Phospholipids from biomembranes, viz., 1,2-dioleoyl-phosphatidylcholine (DOPC), 1,2-dipalmitoyl-phosphatidylcholine (DPPC), and polyethylene glycol-graft-phosphatidyl ethanolamine (PEG-PE) were used as controls. Phospholipid- and polymer-based membranes were prepared to determine the kinetics of A beta fibril formation. Rates of A beta nucleation on the PSf- and DPPC-based membranes were significantly higher than those on the other membranes. A beta accumulation, calculated by the change in frequency of a quartz crystal microbalance (QCM), followed the order: PSf > PLLA > DOPC > PMMA, PVP, DPPC, and PEG-PE. Nucleation rates exhibited a positive correlation with the corresponding accumulation (except for the DPPC-based membrane) and a negative correlation with the molecular weight of the polymers. Strong hydration along the polymer backbone and polymer-A beta entanglement might contribute to the accumulation of A beta and subsequent fibrillation.