Positively charged polyelectrolyte complexes (PECs) were synthesized from two polysaccharides chitosan and arabinogalactan sulfate by self-assembly method as potentially efficient adsorbents for medical and environmental purposes. The obtained PEC particles of submicron size were comprehensively characterized by dynamic and electrophoretic light scattering, FTIR spectroscopy and scanning electron microscopy. The adsorption properties of the synthesized PECs were determined by optical methods using eosin Y as a model anionic dye. A temporal evolution of dye absorption spectra was revealed during the equilibration process in the eosin Y-PEC system; the decay can be described by three characteristic times with maximal value of 35 min. The adsorption within the pH range of 3.0–5.6 can be appropriately described by Langmuir-Freundlich model with the maximal adsorption capacity of 500 mg g−1. The increase of ionic strength has no significant effect on adsorption capacity of PECs, however it results in the increase of the heterogeneity factor from 0.82 up to 2.35. The revealed relationships were discussed in terms of predominantly electrostatic adsorbate-adsorbent interactions. The synthesized PECs demonstrated high colloidal stability along with a high removal efficiency of dye at low pH values that makes them very attractive eco-friendly dye adsorbent with improved biocompatibility.

The photoluminescence (PL) properties of composites obtained by embedding green-emitting semiconductor nanocrystals (NCs) of two different types (thiol-capped CdTe and CdSe/ZnS) into chitosan-based biopolymer particles were investigated. The synthesis of self-assembled particles from oppositely charged polysaccharides involved a preliminary electrostatic binding of positively charged chitosan chains by negatively charged functional groups of NC stabilizing ligands. The amount of NCs and the acidity of the solution were found to be important parameters influencing the PL. The PL properties were mainly discussed in terms of the colloidal stability of the particles and changes in energy gap of NCs. Generally, the obtained biocompatible composites with NCs randomly distributed within a biopolymer particle demonstrated a higher PL resistance to the solution acidity that expands the applicability range of thiol-capped NCs.

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.

An efficient one-pot aqueous synthesis of alloyed Cd1-xHgxTe nanocrystals (NCs) is realized and the influence of the experimental conditions and of the initial composition of the NCs on their optical properties is discussed. This approach obtains stable NCs with an emission tunable in the red and the near infrared (NIR) spectral regions ranging from 640 to 1600 nm thereby covering the second and third telecommunication windows. The high photoluminescence quantum efficiency (PL QE) of these colloids with values up to 55% for red emitting, and up to 60% for NIR emitting samples is indicative of the excellent quality of the NCs.

This work demonstrates a facile one-step aqueous synthesis of blue-emitting glutathione-capped ZnSe(1-x)Te(x) nanocrystals possessing photoluminescence quantum efficiencies of up to 20%. The incorporation of the NCs into a water dispersed polymer was performed in order to enhance their stability and processability resulting in transparent blue-emitting inorganic-organic composites.

The synthesis and photochemical treatment of Zn1-xCdxSe nanocrystals (NCs) capped with thioglycolic acid (TGA) were investigated. A well reproducible method of tuning the luminescence of these NCs from the UV to the blue spectral region was developed. Using this method, stable aqueous NCs with low Cd content exhibiting the photo luminescence quantum efficiency (PL QE) of 20-30% were obtained.

In order to explore synthetic approaches to strongly emitting nanoparticles covering the UV-blue spectral region, the photochemical treatment of ZnSe and Zn(1-x)Cd(x)Se nanocrystals (NCs) capped by thioglycolic acid (TGA) in the presence of Zn(2+) and Cd(2+) ions was investigated. A reproducible method of tuning the luminescence of these NCs from the UV to the blue spectral region was developed. Using this method, stable aqueous NCs emitting in the visible region with photoluminescence (PL) maxima ranging from 390 to 460 nm and with photoluminescence quantum efficiencies (PL QEs) of 20-30% were obtained. The effects of the experimental conditions and of the initial composition of the NCs on their optical properties are discussed.