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

We reported an aqueous plasmon enhanced fluorescence (PEF) nanomaterial, termed as O(113)A(11)F(19)@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 O(113)A(11)F(19)@QDs@SiO2@AuNR was 3.30 times that of bare CdSe QDs. Moreover, O(113)A(11)F(19)@QDs@SiO2@AuNR also showed colloidal stability even when diluted to 5 times. The O(113)A(11)F(19)@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.

Automated summary

This study reported a novel fluorescence enhanced nanomaterial, where the distance between a plasmonic gold nanorod and cadmium selenide quantum dots could be controlled by adjusting the silica layer thickness, leading to fluorescence enhancement. Experimental results showed that the maximum fluorescence enhancement was achieved when the silica layer thickness was 22 nm, and the material remained colloidal stable even when diluted. This material could be used as an advanced bio-probe for sophisticated medical diagnosis.