Direct synthesis of aqueous CdSe/ZnS-based quantum dots using microwave irradiation.
Schumacher-W; Nagy-A; Waldman-WJ; Dutta-PK
J Phys Chem C 2009 Jul; 113(28):12132-12139
This study focuses on an aqueous one-pot method for synthesis of CdSe/ZnS core/shell QDs using microwave radiation. The novelty of the study is the use of Zn(NH3)4 2+ as the zinc source. Using an initial solution with the composition Cd1Se1Zn6MPA20, the QDs obtained upon heating at 160 degrees C for 60 min were not high quality, as evidenced by a quantum yield of 1.5%, due to the poor interface between the core and shell. Postsynthesis UV irradiation of the as-prepared QDs for 30 min could be used to improve the quantum yield to 22%, but the technique is not practical for large-scale applications. By increasing the amount of Cd2+ in the initial solution to Cd4Se1Zn4MPA20, we formed CdSe/CdS/ZnS QDs after heating at 150 degrees C for 90 min, which contained less interfacial trap-states and as a result, had a higher quantum yield of 13%. These QDs were characterized by powder diffraction, electron microscopy, and X-ray photoelectron spectroscopy. Uptake of the microwave-optimized QDs by alveolar macrophages was compared in a side-by-side study against commercial QDs, QDot585. Despite having a lower relative quantum yield (13%) as compared to the commercial QDs (65%), the microwave-synthesized QDs at 20 nM concentrations were readily detected within the macrophages after 20 min of incubation.
Nanotechnology; Inorganic-compounds; Biological-function; X-ray-analysis; Spectrographic-analysis; Cadmium-compounds; Zinc-compounds; Selenium-compounds; Sulfur-compounds
Prabir K. Dutta, Departments of Chemistry and Pathology, The Ohio State UniVersity, Columbus, Ohio 43210
Journal of Physical Chemistry C
Ohio State University