Plasmon-induced double-field-enhanced upconversion nanoprobes with near-infrared resonances for high-sensitivity optical bio-imaging.
High-sensitivity optical imaging can be achieved through improving upconversion photoluminescence (UCPL) efficiency of localized surface plasmon resonance (LSPR)-enhanced excitation and emission. Herein, we report a type of UCPL nanoprobe, Au nanospheres assemblage@Gd2O3:Yb3+/Ln3+(Ln = Er, Ho, Tm), which exhibits emission enhancements from 46- to 96-fold as compared with its Au-free counterparts. The aggregation and interaction among Au nanospheres embedded inside the nanoprobe brings about three characteristic LSPR peaks in visible and near-infrared regions according to simulated and experimental absorption spectra, resulting in both excitation and emission fields simultaneously intensified all through the entire nanoprobe. We addressed a characteristic wavelength dependence on emission amplifications, which could be elucidated by a LSPR-enhanced UCPL mechanism and relevant rate equations that we addressed. The nanoprobe was verified to have a superior capability for optical bio-imaging with a negligible toxicityin vitroandin vivo. This study realizes a synchronous double-field-enhanced upconversion of optical nanoprobein situ, and may gain an insight into its mechanism underlying for LSPR-induced UCPL enhancement.
['Yin|Jinchang|J|0000-0002-0964-7121', 'Zheng|Hongting|H|0000-0001-9879-7334', 'Li|Anming|A|', 'Zhang|Jintao|J|', 'Tian|Li|L|', 'Zhao|Fuli|F|', 'Shao|Yuanzhi|Y|0000-0002-1606-4055']
near-infrared optical imaging photoluminescence surface plasmon resonance upconversion nanoparticle