Biocompatible chitosan-based polyelectrolyte complexes (PECs) doped with xanthene dyes (fluorescein, eosin Y, erythrosin B, rhodamine 6G) were synthesized and characterized by scanning electron microscopy, dynamic light scattering, zeta potential measurements, and absorption and luminescence (including polarized, time-resolved, and phosphorescence) spectroscopy. The results are discussed in terms of the mechanism and rigidity of dye-PEC binding, the heavy-atom effect in dyes and PEC stability. Eosin Y is found to be the optimal dopant, providing both a high dye content in PECs and a high quantum yield of fluorescence.
The paper presents theoretical justification for the possibility of formation of nanoparticle structures with the predefined configuration. The process of formation is the self-organized aggregation of nanoparticles under the action of external resonant laser field. The formation of various nanostructures that contain metallic and semiconducting nanoparticles with resonances in the visible spectrum is considered in the dipole-dipole approximation.
Doping of polymer particles by a fluorophores results in the sensitization within the visible spectral region becoming very promising materials for sensor applications. Colloids of biocompatible chitosan-based polyelectrolyte complexes (PECs) doped with quantum dots (QD) of CdTe and CdSe/ZnS (with sizes of 2.0-2.4 nm) were synthesized and characterized by scanning electron microscopy, dynamic light scattering, ζ-potential measurements, absorption and luminescence (including time-resolved) spectroscopy. The influence of ionic strength (0.02-1.5 M) on absorption and photoluminescence properties of encapsulated into PEC and unencapsulated quantum dots was investigated. The stability of the emission intensity of the encapsulated quantum dots has been shown to be strongly dependent on concentration of quantum dots.
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