Intrinsic fluorescence of PAMAM dendrimers – quenching studies

Intrinsic, non-traditional fluorescence of PAMAM dendrimers that do not possess classical fluorophores has been attracting considerable interest for the last decade.

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Many hypothesis regarding the source of the fluorescence has appeared but some of them are still disputable[1]. In order to shed new light on the nature of the phenomenon we applied quenchers that are normally used to study intrinsic fluorescence of proteins (i.e. KI, CsCl, and acrylamide). KI and acrylamide efficiently quenched steady state fluorescence of PAMAM G2, PAMAM G3, and PAMAM G4 dendrimers[2]. Stern-Volmer plots exhibited a downward curvature that has been elucidated by heterogenousemission. We assume that there are two distinct fluorescent moieties in the dendrimer structure that are characterized by different accessibility to the quenchers[3].

 

References

  1. Larson, C., Tucker, S.; Intrinsic fluorescence of carboxylate-terminated polyamido amine dendrimers.. Appl. Spectr. 2001, 55, 697-683, 10.1366/0003702011952596.
  2. Ji, Y., Yang, X.L., Qian, Y.; Polyamidoamine structure characterization: amide resonance structure of imidic acid (HO-C=N) and tertiary ammonium.. RSC Advances 2014, 4, 49535-49540, 10.1039/c4ra09081k.
  3. Wang, D., Imae, T.; Fluorescence emission from dendrimers and its pH dependence. . J. Am. Chem. Soc. 2004, 126, 13204-13205, 10.1021/ja0454992.