12 research outputs found
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Upconverting nanoparticle micro-lightbulbs designed for deep tissue optical stimulation and imaging.
Optical methods for imaging and stimulation of biological events based on the use of visible light are limited to the superficial layers of tissue due to the significant absorption and scattering of light. Here, we demonstrate the design and implementation of passive micro-structured lightbulbs (MLBs) containing bright-emitting lanthanide-doped upconverting nanoparticles (UCNPs) for light delivery deep into the tissue. The MLBs are realized as cylindrical pillars made of Parylene C polymer that can be implanted deep into the tissue. The encapsulated UCNPs absorb near-infrared (NIR) light at λ = 980 nm, which undergoes much less absorption than the blue light in the brain tissue, and then locally emit blue light (1G4→3H6 and 1D2→3F4 transitions) that can be used for optogenetic excitation of neurons in the brain. The 3H4→3H6 transition will result in the emission of higher energy NIR photons at λ = 800 nm that can be used for imaging and tracking MLBs through thick tissue
Recommended from our members
Upconverting nanoparticle micro-lightbulbs designed for deep tissue optical stimulation and imaging.
Optical methods for imaging and stimulation of biological events based on the use of visible light are limited to the superficial layers of tissue due to the significant absorption and scattering of light. Here, we demonstrate the design and implementation of passive micro-structured lightbulbs (MLBs) containing bright-emitting lanthanide-doped upconverting nanoparticles (UCNPs) for light delivery deep into the tissue. The MLBs are realized as cylindrical pillars made of Parylene C polymer that can be implanted deep into the tissue. The encapsulated UCNPs absorb near-infrared (NIR) light at λ = 980 nm, which undergoes much less absorption than the blue light in the brain tissue, and then locally emit blue light (1G4→3H6 and 1D2→3F4 transitions) that can be used for optogenetic excitation of neurons in the brain. The 3H4→3H6 transition will result in the emission of higher energy NIR photons at λ = 800 nm that can be used for imaging and tracking MLBs through thick tissue
Energy-Looping Nanoparticles: Harnessing Excited-State Absorption for Deep-Tissue Imaging
Near infrared (NIR) microscopy enables
noninvasive imaging in tissue,
particularly in the NIR-II spectral range (1000–1400 nm) where
attenuation due to tissue scattering and absorption is minimized.
Lanthanide-doped upconverting nanocrystals are promising deep-tissue
imaging probes due to their photostable emission in the visible and
NIR, but these materials are not efficiently excited at NIR-II wavelengths
due to the dearth of lanthanide ground-state absorption transitions
in this window. Here, we develop a class of lanthanide-doped imaging
probes that harness an energy-looping mechanism that facilitates excitation
at NIR-II wavelengths, such as 1064 nm, that are resonant with excited-state
absorption transitions but not ground-state absorption. Using computational
methods and combinatorial screening, we have identified Tm<sup>3+</sup>-doped NaYF<sub>4</sub> nanoparticles as efficient looping systems
that emit at 800 nm under continuous-wave excitation at 1064 nm. Using
this benign excitation with standard confocal microscopy, energy-looping
nanoparticles (ELNPs) are imaged in cultured mammalian cells and through
brain tissue without autofluorescence. The 1 mm imaging depths and
2 μm feature sizes are comparable to those demonstrated by state-of-the-art
multiphoton techniques, illustrating that ELNPs are a promising class
of NIR probes for high-fidelity visualization in cells and tissue