Role of tau protein on the photophysical properties of fluorescent carbon dots

Abstract Background Globally, a number of individuals who live with Alzheimer’s disease (AD), an incurable and debilitating disease, is increasing. Tau protein has a structural role, maintains integrity of microtubules and is one of the underlying causes of the tauopathies [1]. It is unfolded and highly soluble under physiological conditions. However, tau protein undergoes post‐translational modifications like phosphorylation and aggregates causing cell death and spreading. In vitro , tau aggregation is typically evaluated using spectroscopic and microscopic methods. Methods Herein, we propose to evaluate the use of carbon dots, an important type of fluorescent nanoparticles, as potential probes for tau protein aggregation. Dual fluorescent carbon dots were used in combination with tau protein, prior and post aggregation. Aggregation of the longest isoform of tau441 was induced using heparin. The fluorescence spectroscopy was used to analyze photophysical properties of carbon dots as a function of monomeric and aggregated tau. Results The fluorescence quenching was observed for all protein containing samples, and was dependent on the aging time used for aggregation. The performance of carbon dots was compared to the standard Thioflavin T assay. Conclusion Data indicate that nanomaterials may be useful platforms for sensing application targeting biomarkers of neurodegenerative diseases. References: [1] a. Andronesi, O. C., Bergen, M. V., Biernat, J., Seidel, K., Griesinger, C., Mandelkow, E., & Baldus, M. (2008). Characterization of Alzheimer’s‐like paired helical filaments from the core domain of tau protein using solid‐state NMR spectroscopy. Journal of the American Chemical Society , 130 (18), 5922‐5928.; b. Jeganathan, S., Hascher, A., Chinnathambi, S., Biernat, J., Mandelkow, E. M., & Mandelkow, E. (2008). Proline‐directed pseudo‐phosphorylation at AT8 and PHF1 epitopes induces a compaction of the paperclip folding of Tau and generates a pathological (MC‐1) conformation. Journal of Biological Chemistry , 283 (46), 32066‐32076.