Microbiosensor for Alzheimer's disease diagnostics: detection of amyloid beta biomarkers

J. Neurochem. (2012) 122, 374381. Abstract Alzheimers disease (AD) affects about 35.6 million people worldwide, and if current trends continue with no medical advancement, one in 85 people will be affected by 2050. Thus, there is an urgent need to develop a cost-effective, easy to use, sensor platform to diagnose and study AD. The measurement of peptide amyloid beta (A beta) found in CSF has been assessed as an avenue to diagnose and study the disease. The quantification of the ratio of A beta 140/42 (or A beta ratio) has been established as a reliable test to diagnose AD through human clinical trials. Therefore, we have developed a multiplexed, implantable immunosensor to detect amyloid beta (A beta) isoforms using triple barrel carbon fiber microelectrodes as the sensor platform. Antibodies act as the biorecognition element of the sensor and selectively capture and bind A beta 140 and A beta 142 to the electrode surface. Electrochemistry was used to measure the intrinsic oxidation signal of A beta at 0.65 V (vs. Ag/AgCl), originating from a single tyrosine residue found at position 10 in its amino acid sequence. Using the proposed immunosensor A beta 140 and A beta 142 could be specifically detected in CSF from mice within a detection range of 2050 nM and 20140 nM respectively. The immunosensor enables real-time, highly sensitive detection of A beta and opens up the possibilities for diagnostic ex vivo applications and research-based in vivo studies.