We report on the synthesis and optical and structural characterization of ultrasmall (<2 nm) CdS nanoparticles with a narrow size distribution of 10% prepared in aqueous and alcohol solutions of polyethyleneimine (PEI). The PEI-stabilized CdS nanoparticles reveal a structured absorption band with the first excitonic maximum at 3.5 eV and broad-band photoluminescence with quantum yields of 12−14% in water, 18−20% in ethanol (80 vol %), and up to 60−70% in solid PEI films at room temperature. The nature of the photoluminescence was studied by using the time- and wavelength-dependent emission measurements. The role of precursor cadmium(II)−PEI complex in the formation of uniform and ultrasmall luminescent CdS nanoparticles, as well as the dynamic emission quenching by water, are discussed. A study of the photochemical properties of PEI-stabilized CdS nanoparticles both under continuous and nanosecond pulse illumination showed excellent stability of solid PEI films incorporating CdS nanoparticles toward UV illumination and reductive character of the CdS nanoparticle photocorrosion in aqueous solutions.

Nanoparticles (NPs) of noble metals, namely gold and silver, remain promising anticancer agents capable of enhancing current surgery- and chemotherapeutic-based approaches in cancer treatment. Bimetallic AgAu composition can be used as a more effective agent due to the synergetic effect. Among the physicochemical parameters affecting gold and silver nanoparticle biological activity, a primary concern relates to their size, shape, composition, charge, etc. However, the impact of metal components/composition as well as metal topological distribution within NPs is incompletely characterized and remains to be further elucidated and clarified. In the present work, we tested a series of colloidal solutions of AgAu NPs of alloy and core-shell type for an antitumor activity depending on metal molar ratios (Ag:Au = 1:1; 1:3; 3:1) and topological distribution of gold and silver within NPs (AucoreAgshell; AgcoreAushell). The efficacy at which an administration of the gold and silver NPs inhibits mouse Lewis lung carcinoma (LLC) growth in vivo was compared. The data suggest that in vivo antitumor activity of the studied NPs strongly depends on gold and silver interaction arising from their ordered topological distribution. NPs with Ag core covered by Au shell were the most effective among the NPs tested towards LLC tumor growth and metastasizing inhibition. Our data show that among the NPs tested in this study, AgcoreAushell NPs may serve as a suitable anticancerous prototype.