Hybrid AuNP@GCD nanosensor for dual-mode dopamine detection and imaging in the Drosophila brain

In this work, we constructed a surface passivated green carbon dot (GCD) integrated with a boronic acid functionalized gold nanoparticle (AuNP@GCD) FRET nanoprobe for the selective detection of dopamine through fluorescence and electrochemical dual methods. The intense blue FL emission of the GCD was decreased after integration with the AuNPs. The feeble FL emission of AuNP@GCDs gradually increased when it came in contact with dopamine owing to the strong diol-boronic acid interaction and restriction of energy transfer. Additionally, there was an 18-fold increment in the current response of the AuNP@GCD deposited electrode towards dopamine as compared to the bare glassy carbon electrode (GCE). The remarkable integration of conductance and fluorescence properties makes our probe suitable for the dual sensing of dopamine in human blood samples. The detection limits for the fluorescence and electrochemical detection are 0.0025 and 0.00026 μM, respectively. Furthermore, a detailed analysis of the toxicity induced by the probe and imaging properties in a fruit fly model (Drosophila melanogaster) suggests that the AuNP@GCD probe is safe and may further find application for dopamine imaging in the brain.