Low irradiance multiphoton imaging with alloyed lanthanide nanocrystals.
Bining TianAngel Fernandez-BravoHossein NajafiaghdamNicole A TorquatoM Virginia P AltoeAyelet TeitelboimCheryl A TajonYue TianNicholas J BorysEdward S BarnardMekhail AnwarEmory M ChanP James SchuckBruce E CohenPublished in: Nature communications (2018)
Multiphoton imaging techniques that convert low-energy excitation to higher energy emission are widely used to improve signal over background, reduce scatter, and limit photodamage. Lanthanide-doped upconverting nanoparticles (UCNPs) are among the most efficient multiphoton probes, but even UCNPs with optimized lanthanide dopant levels require laser intensities that may be problematic. Here, we develop protein-sized, alloyed UCNPs (aUCNPs) that can be imaged individually at laser intensities >300-fold lower than needed for comparably sized doped UCNPs. Using single UCNP characterization and kinetic modeling, we find that addition of inert shells changes optimal lanthanide content from Yb3+, Er3+-doped NaYF4 nanocrystals to fully alloyed compositions. At high levels, emitter Er3+ ions can adopt a second role to enhance aUCNP absorption cross-section by desaturating sensitizer Yb3+ or by absorbing photons directly. Core/shell aUCNPs 12 nm in total diameter can be imaged through deep tissue in live mice using a laser intensity of 0.1 W cm-2.
Keyphrases
- energy transfer
- quantum dots
- high resolution
- metal organic framework
- high speed
- estrogen receptor
- small molecule
- fluorescence imaging
- single molecule
- endoplasmic reticulum
- breast cancer cells
- highly efficient
- metabolic syndrome
- type diabetes
- binding protein
- mass spectrometry
- visible light
- living cells
- insulin resistance
- adipose tissue
- skeletal muscle