Upconverting NIR Photons for Bioimaging

Abstract

Lanthanide-doped upconverting nanoparticles (UCNPs) possess unique anti-Stokes optical properties, in which low energy near-infrared (NIR) photons can be converted into high energy UV, visible, shorter NIR emission via multiphoton upconversion processes. Due to the rapid development of synthesis chemistry, lanthanide-doped UCNPs can be fabricated with narrow distribution and tunable multi-color optical properties. These unique attributes grant them unique NIR-driven imaging/drug delivery/therapeutic applications, especially in the cases of deep tissue environments. In this brief review, we introduce both the basic concepts of and recent progress with UCNPs in material engineering and theranostic applications in imaging, molecular delivery, and tumor therapeutics. The aim of this brief review is to address the most typical progress in basic mechanism, material design as bioimaging tools.

Intraperitoneal Administration of Biointerface‐Camouflaged Upconversion Nanoparticles for Contrast Enhanced Imaging of Pancreatic Cancer

“…The design of our biointerface‐camouflaged nanoprobe combined IP administration strategy of contrast enhanced imaging for pancreatic cancer was illustrated in Scheme . Uniform spherical NaLuF 4 :20%Yb,1%Tm/NaLuF 4 nanoparticles were first prepared with the solvothermal method, then used as seed particles and coated with a layer of NaDyF 4 , resulting in the formation of interesting dumbbell‐shaped hybrid nanostructures. Typical transmission electron microscopy (TEM) images of the NaLuF 4 , NaLuF 4 /NaLuF 4 , and NaLuF 4 /NaLuF 4 /NaDyF 4 nanoparticles were shown in Figure .…”

Vis‐NIR Light‐Responsive Photocatalytic Activity of C3N4−Ag−Ag2O Heterojunction‐Decorated Carbon‐fiber Cloth as Efficient Filter‐Membrane‐Shaped Photocatalyst

“…For instance, Au−La 2 Ti 2 O 7 sensitized with black phosphorus exhibits higher photocatalytic activity than La 2 Ti 2 O 7 in the visible and NIR regions . The second is the decoration of wide‐bandgap semiconductors with the upconversion nanocrystals, where upconversion nanocrystals convert NIR photons to UV or visible photons and then activate the semiconductors . The process of interfacial energy transfer with the absorption of the radiative upconversion emission induces the formation of electron‐hole pairs on the semiconductor for redox reactions , .…”

“…[18] The second is the decoration of wide-bandgap semiconductors with the upconversion nanocrystals, where upconversion nanocrystals convert NIR photons to UV or visible photons and then activate the semiconductors. [19] The process of interfacial energy transfer with the absorption of the radiative upconversion emission induces the formation of electron-hole pairs on the semiconductor for redox reactions. [20,21] So far, many upconversion nanocrystal-semiconductor structures (such as CÀ C 3 N 4 , [22] CÀ TiO 2 , [23] NaYF 4 : Yb, TmÀ TiO 2 , [24,25] NaYF 4 : Yb, TmÀ CdS [26,27] ) being designed and prepared, have greatly enhanced NIR photocatalytic performance compared with those of pure semiconductor materials.…”

Remote Light‐Responsive Nanocarriers for Controlled Drug Delivery: Advances and Perspectives

“…Capitalizing on this advantage, UCL nanoparticles (UCNPs) have emerged as nanotransducers for the development of photocontrolled delivery systems . UCNPs typically consist of a rare‐earth metal fluoride lattice doped with lanthanide ions, such as ytterbium (Yb 3+ ), thulium (Tm 3+ ), or erbium (Er 3+ ) . They are excited in the NIR range and have tunable fluorescence emission depending on the dopant types and their concentrations .…”