Synthesis of Hydrophilic CuInS₂/ZnS Quantum Dots with Different Polymeric Shells and Study of Their Cytotoxicity and Hemocompatibility

In this work, there is a detailed description of the whole process of biocompatible CIS/ZnS QDs production. Special attention was paid to the stability of QDs against photooxidation. It was shown that Cu/In ratio greatly affected not only nanocrystals PLQYs but photostability as well. CIS/ZnS QDs with Cu/In = 1:4 ratio showed high photostability under UV illumination both in toluene and aqueous solutions. Meanwhile, photoluminescence of CIS/ZnS QDs with Cu/In = 1:1 ratio was completely quenched after several hours under UV illumination, though their initial QY was as high as 40% with peak maximum at 740 nm. QDs were transferred to water by polymer encapsulation and were subsequently modified with polyethers Jeffamines, cheap analogues of PEG-derivatives. Three types of hydrophilic QDs differing in size, PEG content, and surface charge were obtained for further investigation and comparison of their cytotoxicity and hemocompatibility. It was shown that both leucocytes size distribution and coagulation activation change after introduction of polyethers into QDs polymeric shell, while red blood cells and platelets size distribution as well as hemolysis rate did not show any different results among different QDs and the polymer itself. All three types of QDs showed only slight cytotoxicity. Confocal microscopy proves penetration of hydrophilic CIS/ZnS QDs inside cells, so the low QDs cytotoxocity cannot be explained by low cellular uptake of the QDs and indicated low QDs toxicity in general.