Thiol-Functionalized Gold Nanodots: Two-Photon Absorption Property and Imaging In Vitro

Abstract

We report here the study of two-photon induced luminescence of 11-mercaptoundecanoic acid functionalized quantum-sized Au nanodots (11MUA-Au nanodots). The X-ray absorption near-edge structure (XANES) measurement at the gold L III edge indicates that the oxidation state of the surface of 11MUA-Au nanodots is best described as Au + . The two-photon absorption (TPA) property of 11MUA-Au nanodots was then investigated via an open aperture Z-scan method. Together with a precise extinction coefficient (i.e., onephoton absorption) extracted from inductively coupled plasma mass spectrometry, the TPA cross section, σ, was deduced to be 8761 ( 175 GM (800 nm) for 11MUA-Au nanodots (diameter 1.33 ( 0.12) in water. Upon dextran encapsulation, 11MUA-Au nanodots was proved to be highly water-soluble, stable, and low in toxicity, which demonstrated its power in two-photon imaging toward human mesenchymal stem cells (hMSCs) in vitro.

Synthesis of DNA-templated fluorescent gold nanoclusters

“…By contrast, featureless absorption spectra are observed for the solutions prepared at lower pH values. This fact indicates that the fluorescent Au NCs produced at the weakly acidic conditions should be smaller than 2 nm in diameter [57,58], which is in agreement with the TEM results and the Jellium model-based prediction. Previously, the similar absorption spectra with such featureless behaviors were observed for fluorescent Au NCs by their intensities decaying roughly exponentially toward the visible region from the UV region [14,36,38,39].…”

Gold nanoclusters with enhanced tunable fluorescence as bioimaging probes

“…Two photon‐based bioimaging has more advantage over conventional single‐photon imaging, because it can image deeper tissue and efficiently suppress background signal. Dextran functionalized, mercaptoundecanoic acid capped FGCs have been used to label human mesenchymal stem cells and two‐photon imaging under 800 nm excitation shows bright green emission due to FGCs . Glutathione protected FGCs are reported to have higher two photon cross‐section efficiency than mercaptoundecanoic acid capped FGCs .…”

Noble Metal Nanomaterials

“…Gold nanorods have proven to be an effective fluorescent agent for imaging a variety of biological species, such as cancer cells [392][393][394], Bacillus spores [395], and mesenchymal stem cells [396]. Wang et al demonstrated that gold nanorods possess strong TPL intensities with a cos 4 dependence on the incident polarization [397].…”