Nanoconjugates of CdTe@ZnS quantum dots with cobalt tetraamino-phthalocyanine: Characterization and implications for the fluorescence recognition of superoxide anion

The covalent linking of thiol-capped CdTe@ZnS QDs with cobalt tetraamino-phthalocyanine (CoTAPc) has been successfully carried out. Several techniques such as time-resolved fluorescence measurements, thermal gravimetric analysis, transmission electron microscopy and spectrophotometric techniques were employed to characterize the nanoconjugates. Covalent binding of the QDs with CoTAPc resulted in the fluorescence quenching of the former. In the presence of varying concentrations of superoxide anion (O2−), the fluorescence of the QDs in the conjugate was gradually enhanced and the detection limits obtained were 2.1 and 2.4 nM for the smaller and larger QDs, respectively. Based on the excellent selectivity displayed by the nanoconjugates towards O2− over other biologically active species, a potential nanosensor was developed.

Graphical abstractThe covalent linking of thiol-capped CdTe@ZnS QDs with cobalt tetraamino-phthalocyanine results in the fluorescence quenching of the former, the resulting conjugates can detect superoxide anion (O2−) with detection limits of about 2 nM.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Cobalt tetraamino-phthalocyanine was coordinated to CdTe@ZnS quantum dots. ► The fluorescence emission of quantum dots was quenched by the phthalocyanine. ► The conjugates could detect superoxide anion.