Polarity studies of single polyelectrolyte layers in polyelectrolyte multilayers probed by steady state and life time doxorubicin fluorescence

MARTINELLI, HERNAN; TASCA, ELISAMARIA; ANDREOZZI, PATRIZIA; LIBERTONE, SARA; RITACCO, HERNAN; GIUSTINI, MAURO; MOYA, SERGIO E.

JOURNAL OF COLLOID AND INTERFACE SCIENCE

ACADEMIC PRESS INC ELSEVIER SCIENCE

Año: 2022 vol. 607 p. 153 - 162

0021-9797

HypothesisPolarity in polyelectrolyte multilayers (PEMs) may vary from the inner to the top layers of the film as the charge compensation of the layers is more effective inside the PEMs than in outer layers. Doxorubicin (DX) is used here to sense polarity at the single polyelectrolyte level inside PEMS.ExperimentalDX is complexed electrostatically to a polyanion, either polystyrene sulfonate (PSS) or polyacrylic acid (PAA) and assembled at selected positions in a multilayer of the polyanion and polyallylamine hydrochloride (PAH) as polycation. Local polarity in the layer domain is evaluated through changes in the intensity ratio of the first to second band of spectra of DX (I1/I2 ratio) by steady state fluorescence, and by Lifetime fluorescence.FindingsFor PAH/PSS multilayers show a polarity similar to water with DX/PSS as top layer, decreasing to I1/I2 ratios similar to organic solvents as the number of polyelectrolyte layers assembled on top increases. For PAH/PAA multilayers, polarity values reflect a more polar environment than water when DX/PAA is the top layer, remaining unaltered by the assembly of polyelectrolyte layers on top. Results show that different polar environments may be present in a PEM when considering polarity at the single layer level.