Amyloid Beta Monitoring Through a Ru(II) Complex: Luminescent Probe Candidate for Early Diagnosis of Alzheimer’s Disease

Alzheimer’s disease is the most common cause of dementia in elderly people and it is responsible for the progressive decline of their cognitive and motor functions.1 Once the disease has progressed, amyloid beta aggregates are found in the patient’s brain and are known to disturb the normal brain function. With that in mind, a ruthenium metal complex was developed to, with its different sets of ligands, act as a probe to monitor in real time the aggregation process of amyloid beta through its luminescence. The initial luminescence studies showed that our ruthenium complex does in fact bind to the amyloid beta protein from early stages of aggregation to fibril formation. The intrinsic fluorescence of the peptide is increased significantly in the presence of ruthenium complex. The aggregation process of many fragments of the A1-40 peptide– A1-28, A15-21, A11-22, A25-35 and A29-40 were tested with the complex. Our preliminary studies through emission lifetime have shown that there the complex is able to interact more significantly with the A11-22 and A1-28 and less significantly with A25-35 and A29-40. It is possible to see that the aggregates increase in size with the incubation time and tend form plaques. Fibrils could be seen prominently in 120 minutes of incubation whereas in 240 minutes the fibrils tend to form fibril-plaques. When the complex was added in the 1:1 proportion is possible to see a significant difference in the size of aggregates in 240 minutes of incubation. [