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

Abstract

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.

Labeling and in vivo visualization of transplanted adipose tissue-derived stem cells with safe cadmium-free aqueous ZnS coating of ZnS-AgInS2 nanoparticles

“…Thus, the development of novel QDs with extremely low cytotoxicity (especially Cd-free alternatives) is necessary for further advancement of QD technology15161718. There have been some reports about the cadmium-free QDs such as carbon or CuInS 2 /ZnS QDs192021. We previously reported the facile synthesis of ZnS-AgInS 2 (ZAIS) as a cadmium-free QD, and confirmed that ZAIS was useful as a color-adjustable fluorophore mainly for solar cells2223.…”

Optical Properties, Synthesis, and Potential Applications of Cu-Based Ternary or Quaternary Anisotropic Quantum Dots, Polytypic Nanocrystals, and Core/Shell Heterostructures

“…The X-ray absorption near-edge structure (XANES) results demonstrated the high chemical stability of CIS and CIS/ZnS QDs in Caenorhabditis elegans for a range of exposure times. Speranskaya et al has studied the photostability and cytotoxicity of CIS/ZnS heterostructures [190]. It was found that the photostability of CIS/ZnS core-shell structures under constant UV illumination depends on the Cu/In ratio used for CIS core synthesis.…”

Highly Luminescent Water-Dispersible NIR-Emitting Wurtzite CuInS2/ZnS Core/Shell Colloidal Quantum Dots

“…20 Nevertheless, to date high PLQYs (≥50%) have only been reported for CIS/ZnS and CIS/CdS core/shell QDs with core diameters below 4 nm and PL up to 750 nm. 17−19,21−24 Although luminescent CIS QDs larger than 4 nm have also been reported, 21,25−27 their size and shape dispersion is typically quite large due to the difficulty in balancing the reactivities of multiple precursors (In, Cu, S). 20 Partial topotactic Cu + for In 3+ cation exchange (CE) in template Cu 2- x S nanocrystals (NCs) has been recently established as an effective strategy to circumvent these limitations, 28,29 allowing the preparation of monodisperse luminescent CIS QDs and NCs of sizes and shapes that would not be easily attainable by direct routes.…”

“…Overgrowth of a zinc blende ZnS shell on CP CIS QDs has been shown to effectively passivate these surface defects, thereby increasing the PLQYs to values as high as 80%, while excellent stability is imparted with preservation of the inherently low toxicity of CIS QDs. 17−19,22,23,27 However, ZnS shelling protocols for WZ CIS QDs are still underdeveloped, as the highest PLQY reported to date for WZ CIS/ZnS QDs is only 1%. 30,32 …”