Seed-Dependent Deposition Behavior of A(beta) Peptides Studied with Wireless Quartz-Crystal-Microbalance Biosensor

摘要

Real-time monitoring of the deposition processes of A(beta)1-40 and A(beta)1-42 peptides on various seeds has been performed using a 55 MHz wireless quartz-crystal microbalance (QCM) over long-time periods (approx40 h). Dissolved peptide solutions were stirred for nucleation and growth of seeds at pH velence 7.4 and 4.6, which were immobilized on the sensor chips. The isolated A(beta) peptides were then flowed at the neutral pH, focusing on the interaction between the seeds and the monomers (or small multimers), excluding other interactions among seeds and other aggregates. The thioflavin-T fluorescence assay and atomic-force microscopy were used for evaluating structures of the seeds and deposited aggregates. The deposition rate, determined by the frequency decrease, is about 100 monomersm~(2)/year in the case of fibril formation. The notable deposition behavior was observed in the deposition of A(beta)1-40 peptide on A(beta)1-42 seeds grown at the lower pH, which can be an important model for Alzheimer's disease.