High-throughput analysis of Alzheimer's beta-amyloid aggregation using a microfluidic self-assembly of monomers.

The principal histopathological feature of Alzheimer's disease is the presence of beta-amyloid (Abeta) aggregates in the gray matter of the brain, and researchers believe that various environmental factors play significant roles in the conformational change and self-assembly of Abeta peptides. Therefore, discovering a rapid and convenient analytical method of evaluating the environmental factors on Abeta aggregation would have a considerable impact. Herein we report our development of a novel microfluidic screening system enabling high-throughput analysis, low-consumption of reagents, and short analytical time. Microchannels with a cross-sectional dimension of 100 microm x 100 microm were immobilized with Abeta monomers via N-hydroxysuccinimide ester activation of the internal surfaces, and then a fresh Abeta monomer solution mixed with different small molecules or metal ions was continuously introduced into the microchannels to induce Abeta aggregation. In this work, we investigated (1) the temporal evolution of Abeta aggregation within microchannels, (2) the high-throughput screening of the inhibitory effect of 12 small molecules against Abeta aggregation, and (3) the effect of different metal ions (Fe(3+), Cu(2+), Zn(2+), and Al(3+)) on Abeta aggregation by using thioflavin T (ThT)-induced fluorescence microscopy and ex situ atomic force microscopy. The microfluidic system should contribute to a simultaneous analysis of multiple environmental factors affecting amyloid aggregates in a parallel manner and to screen therapeutic small molecules prior to their in vivo evaluation.