Upconversion nanoparticles

Lanthanide/CaF2 upconversion nanoparticles coated with poly(actylic acid) (PAA) and then PEI showed the ability to internalize into rat mesenehymal stem cells and were not observed to exocytose. In contrast, nanoparticles without the eovalendy linked PAA or without PEI showed veiy different behaviour, as they were found to aggregate and did not enter the eells. 

ALA, 5-aminolevulinic acid BSA, bovine serum albumin Ce6, chlorin e6 HP, hematoporphyrin M-540, merocyanine 540 02, singlet oxygen PAA, poly(acrylic acid) PDT, photodynamic therapy PEG, polyethylene glycol PS, photosensitiser PTT, photothermal therapy RB, Rose Bengal SPCD, silicon phthalocyanine dihydroxide UCNP, upconversion nanoparticles ZnPc, zinc phthalocyanine. 

In this chapter, we first divide NIR NMs into five species carbon-based materials, quantum dots (QDs), noble metal-based nanoparticles (NPs), upconversion nanoparticles (UCNPs), and narrow-bandgap semiconductors. Then, we focus primarily on the progress of their toxicity studies in the past several years, discuss in detail how the biophysicochemical properties of NIR NMs influence their in vitro and in vivo toxicity, present a broad overview of the available in vitro and in vivo toxicity assessments of NIR NMs, and finally frame the future outlook for NIR NMs by highlighting areas of exceptional promise and challenges. Our emphasis here is mainly on discussion that could offer future opportunities to design and create NIR NMs with good biocompatibility as well as excellent functionalities, rather than attempting to provide a complete historical survey. 

Lanthanides Liuninescence Applications Liunines-cent Bioprobes Near-Infrared Materials The Electronic Stracture of the Lantiianides Upconversion Nanoparticles for Bioimaging Apphcations. 

Scheme 1 Surface modifications of Y2O3 upconversion nanoparticles with PAA, PEG, and NIR dye. (Reproduced from Ref. 57 with permission of The Royal Society of Chemistry.)...

Figure 7 Excitation and emission wavelengths of luminescence sources are plotted on a graph. Fluorophores are helow the reflectance line because they absorb a higher energy photon and emit a lower energy photon. Upconversion nanoparticles are fundamentally different a high-energy photon is emitted following absorption of two low-energy photons. (Reproduced with permission from Ref. 68. The Optical Society, 2008.)...

LbL = layer-by-layer Ln = lanthanide LSS = liqnid-solid-solntion NIR = near-infrared NPs = nanoparticles OA = oleic acid ODE = octadecene PA = photon avalanche PAA = polyacrylic acid PAH = poly(allyIamine hydrochloride) PEI = polyethylenimine PSS = poly(sodium 4-styre-nesnlfonate) PVP = polyvinylpyrrohdone QDs = qnantum dot SAUCI = smaU-animal upconversion imager SHG = second-harmonic generation STPA = simultaneons two-photon absorption TOPO = trioctylphosphine oxide TPA = two-photon absorption UCNPs = Upconversion nanoparticle UV = nlfraviolet. 

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