An aqueous gold nanorod and CdSe quantum dots hybrid nanomaterial: A potential plasmon enhanced fluorescence structure for bio-probe fabrication

Abstract

We reported an aqueous plasmon enhanced fluorescence (PEF) nanomaterial, termed as O113A11F19@QDs@SiO2@AuNR, where the fluorescence enhancement fold was highly dependent on the distance between cadmium selenide quantum dots (CdSe QDs) and the plasmonic gold nanorod (AuNR). The distance between AuNR and CdSe QDs was controlled by adjusting the thickness of the silica layer. When the thickness of silica layer was 22 ± 1.2 nm, the maximum fluorescence enhancement of O113A11F19@QDs@SiO2@AuNR was 3.30 times that of bare CdSe QDs. Moreover, O113A11F19@QDs@SiO2@AuNR also showed colloidal stability even when diluted to 5 times. The O113A11F19@QDs@SiO2@AuNR could be used as advanced bio-probe for sophisticated medical diagnosis. The interaction between CdSe QDs and AuNR was investigated using a finite difference time domain (FDTD) simulation. The simulation results demonstrated that the electromagnetic field generated from AuNR can enhance the excitation and radiation decay rate of CdSe QDs, which results in the fluorescence enhancement. The spectra overlap of CdSe QDs with longitudinal localized surface plasmon resonance band (L-SPR) of AuNR and an appropriate distance between AuNR and QDs were both crucial factors for the fluorescence enhancement. The reported findings provide a valuable guidance to rationally design advanced bio-probe for sophisticated medical diagnosis.