Driven by their outstanding optical properties, the use of semiconductor nanocrystals in real-world applications is intensively explored; the most advanced being biological imaging and detection as well as optoelectronics. In the quest for Cd- and Pb-free QDs, indium phosphide is handled as one of the most promising alternatives, as size-tunable emission throughout the visible and NIR range with high photoluminescence quantum yield has been reported. Still a number of challenges have to be met in order to bring their optical properties on the same level as those of CdSe based QDs. First, the emission line width of InP QDs is significantly broader with the best values reported around 40-50 nm at FWHM. Therefore a better control of the size distribution is required, which is difficult due to the specific properties of InP, like stronger size-dependence of emission than CdSe, and the covalent character of binding. The latter factor implies the use of highly reactive precursors and elevated temperatures, which severely limits the possibilities of tuning the reaction kinetics towards a regime of "size focusing". Second, it remains challenging to synthesize strongly luminescing InP based QDs with emission in the 600-750 nm range. After a brief outline of the current state in this field, we will present our current research aiming at resolving the above-mentioned shortcomings. Furthermore, we will present in vivo toxicity studies aimed to compare core/shell InP/ZnS QDs, core shell/shell InPZn/ZnSe/ZnS QDs, and CdSe/ZnS QDs, all presenting a Penicillamine layer. By using as toxicity model the freshwater polyp Hydra vulgaris, we determined several toxicity endopoints in vivo (morphology, reproduction rate, efficiency of regeneration), ex vivo (cell apoptosis rate) and at molecular level (changes in expression levels of two marker genes). Results show protective effect of the shell around the InP core and the higher toxic effect of Cd containing nanoparticles, supporting the choice Indium phosphide as valid alternative for safe and advanced biological applications.
InP QDs - a good alternative to CdSe?
Claudia Tortiglione;
2016
Abstract
Driven by their outstanding optical properties, the use of semiconductor nanocrystals in real-world applications is intensively explored; the most advanced being biological imaging and detection as well as optoelectronics. In the quest for Cd- and Pb-free QDs, indium phosphide is handled as one of the most promising alternatives, as size-tunable emission throughout the visible and NIR range with high photoluminescence quantum yield has been reported. Still a number of challenges have to be met in order to bring their optical properties on the same level as those of CdSe based QDs. First, the emission line width of InP QDs is significantly broader with the best values reported around 40-50 nm at FWHM. Therefore a better control of the size distribution is required, which is difficult due to the specific properties of InP, like stronger size-dependence of emission than CdSe, and the covalent character of binding. The latter factor implies the use of highly reactive precursors and elevated temperatures, which severely limits the possibilities of tuning the reaction kinetics towards a regime of "size focusing". Second, it remains challenging to synthesize strongly luminescing InP based QDs with emission in the 600-750 nm range. After a brief outline of the current state in this field, we will present our current research aiming at resolving the above-mentioned shortcomings. Furthermore, we will present in vivo toxicity studies aimed to compare core/shell InP/ZnS QDs, core shell/shell InPZn/ZnSe/ZnS QDs, and CdSe/ZnS QDs, all presenting a Penicillamine layer. By using as toxicity model the freshwater polyp Hydra vulgaris, we determined several toxicity endopoints in vivo (morphology, reproduction rate, efficiency of regeneration), ex vivo (cell apoptosis rate) and at molecular level (changes in expression levels of two marker genes). Results show protective effect of the shell around the InP core and the higher toxic effect of Cd containing nanoparticles, supporting the choice Indium phosphide as valid alternative for safe and advanced biological applications.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
