Exploring The Correlation Between Intrinsic Fluorescence And Protein Aggregation

Progressive nerve and brain cell damage associated with Alzheimer's disease, has been attributed to the build‐up of aggregated proteins. Detection of amyloid aggregation, through the measuring their intrinsic fluorescence, could be a valuable approach for early detection of the disease.The purpose of our study was to teach the correlation between intrinsic fluorescence and protein aggregation within the visible range in an interdisciplinary undergraduate summer research course. Students used purified green fluorescent protein (GFP, Biorad), unpurified enhanced green fluorescent protein (EGFP, Edvotek) and liquid silk fibroin protein (SFP, Silktap) as model proteins. We focused our experimentation on sonication conditions that led to gelation of SFP due to β‐sheet formation. Using single model proteins and combined protein solutions, samples were sonicated and fluorescence was measured at 405 and 500nm wavelengths. UV light was also used to compare the green fluorescence emitted by the GFP and EGFP samples.Our results showed an increase in fluorescence of single model protein solutions post‐sonication when compared with the pre‐sonication protein solutions. When EGFP and SFP solutions were combined and sonicated together, we observed a decrease in fluorescence. Similar results were obtained when purified GFP and SFP solutions were combined and sonicated.In future experiments, students are planning to design a minimally invasive device able to detect early stages of amyloid aggregation in the brain as a senior project for an undergraduate biomedical engineering major.