Biosurfactant templated quantum sized fluorescent gold nanoclusters for in vivo bioimaging in zebrafish embryos

• Biosurfactant templated bluish-green emitting gold nanoclusters with less than 1.4 nm have been reported.
• Fluorescence and lifetime measurements showed that the synthesized AuNC is composed of a single emitting species.
• The synthesized clusters were used as a fluorescent probe for in vivo bioimaging in Zebrafish embryos.

We report the biosurfactant (sodium cholate) templated bright bluish-green emitting gold nanoclusters (AuNCs) by green chemical approach. Optical properties of the AuNCs were studied using UV–vis and luminescence spectroscopy. Lifetime of the fluorescent AuNCs was measured using time correlated single photon counting technique (TCSPC). High-resolution transmission electron microscopy (HR-TEM) and dynamic light scattering (DLS) were used to measure the sizes of the clusters. In-vivo toxicity and bioimaging studies of sodium cholate (NaC) templated AuNCs were carried out at different developmental stages of zebrafish embryos. The survival rate, hatching rate, heart rate, malformation and apoptotic gene expression experiments shows no significant toxicity in developing embryos up to 100 μL/mL of AuNCs concentration and the AuNCs stained embryos exhibited green fluorescence with high intensity over the period from 4 to 96 hpf (hours post fertilization) which shows that AuNCs were stable in living organisms.

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