Paramagnetic Gd-functionalized Fluorescent Gold Nanoclusters For Optical And Magnetic Resonance Imaging

Bull serum album stabilized fluorescent Au nanoclusters (AuNC@BSA) with the functionalization of Gd3+-DTPA were applied as potential optical and magnetic resonance imaging nanoprobes. These composite probes were obtained by covalently conjugating DTPA onto the outlayer of high fluorescent AuNC@BS A, after which Gd3+was complexed onto the surface of AuNC@BSA. The process of modifying the surface of Au nanoclusters has been confirmed by UV-vis spectrometry, inductively coupled plasma-mass spectrometry (ICP-MS), X-ray photoelectron spectroscopy (XPS). It was noticed that the introduction of Gd-DTPA did not produce any change in the fluorescence emission wavelength and intensity of AuNC@BSA. Longitudinal proton relaxivities (r1) of these nanoprobes are higher than the positive contrast agents like Gd-DTPA, which are commonly used for clinical magnetic resonance imaging. Fluorescence imaging and Ti-weighted magnetic resonance imaging revealed that these nanoprobes suited for dual modality imaging application:the Au nanoclusters provide the capability for fluorescence imaging, the great enhancement of the ri relaxivity makes them well suited for magnetic resonance imaging. This paves the way for bimodal Au-nanocluster-based nanoprobes for a variety of imaging applications.