Fluorescent nanodiamonds (FND) with non-photo bleachable fluorescence from their nitrogen vacancy centers(NV), are an emerging class of material in bioimaging. FND in optical imaging can provide real-time living cell images, and was applied for long term in vitro or in vivo imaging as well as single molecular tracking. In this work, FND labelled with gold nanoparticles (AuNPs) were prepared by protein coating and purified by analytical ultracentrifugation sedimentation. The surface plasmon resonance effect of AuNP significantly decreased the lifetime and improved optical emission of NV centers, which allowed the reduction of laser power, and consequently, minimized the irradiation time required for FND excitation, thus making the FND−Au hybrids well-suited for decreased photo-toxicity in optical imaging.<br/>Electron microscopy images with down to nanometers resolution, provide more detailed information even for subcellular organelles study. While the contrast of TEM images is dependent of sample density, thus the carbon crystal of FND cannot provide good contrast. The FND-Au hybrids were well-distinguishable from the dense subcellular background with high contrast due to the labeling with AuNPs thus facilitating detailed investigations by TEM. In this way, FND-Au cellular distribution and penetration of endosomal membranes was studied by TEM, and a unique flickering behavior of the FNDs was recorded by 3D scanning transmission electron microscopy (STEM) for the first time. Due to their excellent optical features, high contrast in electronic microscope imaging, their capability of endosomal escape, and high biocompatibility, the FND−Au hybrids reported herein represent a powerful platform for studying cellular activity and functions with single particle resolution.

Fluorescent nanodiamond labelled with gold nanoparticles for enhanced optical and electron microscopy imaging

253rd National Meeting (2017)

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