Study of Alzheimer's Disease-Related Biophysical Kinetics with a Microslit-Embedded Cantilever Sensor in a Liquid Environment

Abstract

A microsized slit-embedded cantilever sensor (slit cantilever) was fabricated and evaluated as a biosensing platform in a liquid environment. In order to minimize the degradation caused by viscous damping, a 300 x 100 mu m(2) (length x width) sized cantilever was released by a 5 mu m gap-surrounding and vibrated by an internal piezoelectric-driven self-actuator. Owing to the structure, when the single side of the slit cantilever was exposed to liquid a significant quality factor (Q = 35) could be achieved. To assess the sensing performance, the slit cantilever was exploited to study the biophysical kinetics related to A beta peptide. First, the quantification of A beta peptide with a concentration of 10 pg/mL to 1 mu g/mL was performed. The resonant responses exhibited a dynamic range from 100 pg/mL to 100 ng/mL (-56.5 to 774 Delta Hz) and a dissociation constant (K-D) of binding affinity was calculated as 1.75 nM. Finally, the A fi self-aggregation associated with AD pathogenesis was monitored by adding monomeric A fi peptides. As the concentration of added analyte increased from 100 ng/mL to 10 ng/mL, both the frequency shift values (813 to 1804 Delta Hz) and associate time constant increased. These results showed the excellent sensing performance of the slit cantilever overcoming a major drawback in liquid environments to become a promising diagnostic tool candidate.