Porphyrin decorated CdSe quantum dots for direct fluorescent sensing of metal ions
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In this study, we report on a novel hybrid structure for the direct sensing of metal ions based on the use of CdSe quantum dots functionalized with tetrapyridyl-substituted porphyrin, a cation-selective carrier. It is shown that the porphyrin ion carrier coordinates to Cd atoms of the CdSe quantum dots through the Lewis basic pyridyl groups. The porphyrin-quantum dot ligation allows for the direct communication between the porphyrin and the underlying CdSe quantum structure. The quantum yield of CdSe is maintained despite the robust capping generated when the unmetallated porphyrins coordinate onto the quantum dots. Upon coordination with zinc ions, this porphyrin capping is shown to strongly contribute to the increase in the fluorescence efficiency of CdSe, via an activating interaction with the quantum dots surface. The results provide the grounds for the development of highly sensitive and selective nano-optode sensing systems.
KeywordsQuantum dots Porphyrin Fluorescence Metal ions
This study was supported by “Fundação para a Ciência e a Tecnologia” (M. F. Frasco Post-Doctoral grant SFRH/BPD/40876/2007) and by the European Commission Program NANOMYC (Contract 036812). The authors acknowledge Dr. M. Čomor (Vinca Institute for Nuclear Sciences, Belgrade, Serbia) for kindly providing the CdSe QDs and Dr. R. Buiculescu for the TEM pictures.
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