Towards biocompatible NIR-II nanoprobes - transfer of hydrophobic Ag2S quantum dots to aqueous solutions using phase transfer catalysed hydrolysis of poly(maleic anhydride-alt-1-octadecene)

Publication date: Available online 2 May 2019Source: Colloids and Surfaces B: BiointerfacesAuthor(s): Rotko Grzegorz, Cichos Jakub, Wysokińska Edyta, Karbowiak Mirosław, Kałas WojciechAbstractDevelopment of protocols for transferring of hydrophobic quantum dots (QDs) into aqueous solution is of special importance for their biomedical applications. Particularly, hydrophilization of Ag2S without quenching of photoluminescence is a great challenge. Application of standard protocol for amphiphilic polymer coating of hydrophobic Ag2S nanocrystals failed, whereas ligand exchange and direct synthesis of Ag2S in aqueous solution leads to poorly emitting materials. In this paper we present the facile method for transferring of Ag2S QDs into aqueous solution employing the phase transfer catalysed hydrolysis of a commercially available polymer - poly(maleic anhydride-alt-1-octadecene), (PMAO) mixed with QDs solution in chloroform catalysed by water solution of tetramethylammonium hydroxide. Because the original surface ligands are retained and we do not use solvents (like THF) detrimental for Ag2S emission, the modification does not deteriorate photoluminescence properties and quantum yield of modified QDs in aqueous solution reaches 60% of that for hydrophobic QDs in chloroform. The hydrodynamic diameter of modified water soluble Ag2S QDs is about 10 nm and is only slightly larger than their original size. Moreover, the polymer coated nanocrystals are not aggregated and are stable...
Source: Colloids and Surfaces B: Biointerfaces - Category: Biochemistry Source Type: research