Fluorescence Anisotropy Dimensions of Perylene-Labeled Foldamers in Solution Determined by Time-Resolved Fluorescence Anisotropy Hunter Little, Jean Duhamel | Department of Chemistry | University of Waterloo – Xuesong Li, Ivan Huc | Institut Européen de Chimie Biologique Université Bordeaux 2 | 33600 Pessac, France Introduction Procedure Effect of Temperature Foldamers are novel synthetic macromolecules that naturally fold. They adopt a well defined conformation in the crystalized form, but little is known about them in solution. Samples were prepared by dissolving the foldamers in distilled in glass toluene purchased from Caledon and diluted to 2.3 x 10-6 M Fluorescence decays analysed by fitting the polarized decays to the Equations 1 and 2: The rotational time is obtained from the expression of the anisotropy given in Equation 3. Foldamers (1) Macromolecules that naturally fold Made of aromatic or peptide analogue backbones. Behave similarly to naturally occurring macromolecules such as DNA Offer new insight into helical handedness (2) Figure 4. Rotational time adjusted for temperature and solvent viscosity plotted as a function of foldamer length (Δ) T= 25 °C, (●) 35 °C (◊), and 75 °C (3) Fluorescence Anisotropy Rotational Time After adjusting for temperature and viscosity changes, the corrected rotational time (fT/h) is not affected by temperature. It demonstrates that the foldamers do not denature in toluene up to a temperature of 75 oC. Uses plane polarized light to measure the rotational diffusion coefficient of the dye in solution A larger anisotropy value corresponds to a more hindered dye Conclusions Foldamer Structure Foldamers seem to retain their helical conformation while in solution Annealing the foldamers at high temperature does not denature the foldamers over the temperature range examined Acknowledgments Figure 3. Rotational Time of Foldamers as determined by Fluorescence anisotropy. Figure 1. Chemical structure of foldamers. Degree of polymerization is equal to 2, 8,16, or 32 Works Cited Steady increase in rotational time as length increases before it seems to plateau around 20 – 25 units Approximating the foldamers as cylindrical helices, the diameter was calculated to be 1.4 nm While this is smaller than the diameter of 2 nm determined from X-ray crystallography, the difference might be attributed to the difference in experimental techniques, fluorescence anisotropy being based on the Brownian motion of the macromolecule in solution. Li, X.; Qi, T.; Srinivas, K.; Massip, S.; Maurizot, V.; Huc, I. Synthesis and Multibromination of Nanosized Helical Aromatic Amide Foldamer via Segmetn-Doubling Condensation. Org. Lett. 2016,18 1044 – 1047. Guichard, G.; Huc, I. Synthetic Foldamers. Chem. Commun. 2011, 47, 5933 – 5941. Goodman, C.; Choi, S.; Shandler, S.; DeGrado, W. Foldamers as Versatile Frameworks for the Designs and Evolution of Function. Nat. Chem. Biol. 2007, 3, 252 – 262. Srivastava, A.; Waite, J. H.; Stucky, G. D.; Mikhailovsky A; Fluorescence Investigations into Complex Coacervation between Polyvinylimidazole and Sodium Alginate. Macromolecules 2009, 42, 2168 – 2176. Lakowicz, J. R.. Principles of Fluorescence Spectroscopy (3rd ed.) . New York: Springer Science 2006, 353 – 412. Fowler, M.; Duhamel, J., Fluorescence Anisotropy of the Per-Qx Samples Prepared by Xuesong Li in Bordeaux. Internal Report 2015. Figure 2. X-Ray structure of 48-mer foldamer helix1