14 research outputs found
Li+ ion doping: an approach for improving the crystallinity and upconversion emissions of NaYF4:Yb3+, Tm3+ nanoparticles
808 nm driven Nd 3+
The in vivo biological applications of upconversion nanoparticles (UCNPs) prefer excitation at 700-850 nm, instead of 980 nm, due to the absorption of water. Recent approaches in constructing robust Nd3+ doped UCNPs with 808 nm excitation properties rely on a thick Nd3+ sensitized shell. However, for the very important and popular Frster resonance energy transfer (FRET)-based applications, such as photodynamic therapy (PDT) or switchable biosensors, this type of structure has restrictions resulting in a poor energy transfer. In this work, we have designed a NaYF4:Yb/Ho@NaYF4:Nd@NaYF4 core-shell-shell nanostructure. We have proven that this optimal structure balances the robustness of the upconversion emission and the FRET efficiency for FRET-based bioapplications. A proof of the concept was demonstrated for photodynamic therapy and simultaneous fluorescence imaging of HeLa cells triggered by 808 nm light, where low heating and a high PDT efficacy were achieved
Effect of protein molecules on the photoluminescence properties and stability of water-soluble CdSe/ZnS core-shell quantum dots
Size-dependent lanthanide energy transfer amplifies upconversion luminescence quantum yields
Optical upconversion from lanthanide-doped nanoparticles is promising for a variety of applications ranging from bioimaging, optogenetics, nanothermometry, super-resolution nanoscopy and volumetric displays to solar cells. Despite remarkable progress made in enhancing upconversion to fuel these applications, achieving luminescence of upconversion nanoparticles (UCNPs) that is comparable to or higher than the bulk counterparts has been challenging due to nanoscale-induced quenching effects. Here we demonstrate a size-dependent lanthanide energy transfer effect in a conceptual design of hexagonal sodium yttrium fluoride (NaYF4) coreâshellâshell NaYF4@NaYF4:Yb/Tm@NaYF4 UCNPs with depleted surface quenching. We show that precise control over the domain size (or the thickness of the middle shell doped with ytterbium (Yb) and thulium (Tm) from 1.2 to 13 nm) increases the lanthanide energy transfer efficiency (from 30.2 to 50.4%) and amplifies the upconversion quantum yield to a high value of 13.0 ± 1.3% in sub-50 nm UCNPs (excitation: 980 nm, 100 W cmâ2), which is around fourfold higher than the micrometre-scale hexagonal NaYF4:Yb/Tm bulk counterparts. Spectroscopic studies and theoretical microscopic modelling reveal that long-range lanthanide energy transfer (>9.5 nm) takes place and underlies the observed size-dependent phenomena. Demonstration of size-dependent lanthanide energy transfer and upconversion quantum yields at the nanoscale transforms our long-existing conceptual understanding of lanthanide energy transfer (size independence), thereby having important implications for applications of lanthanide nanophotonics and biophotonics.</p
Targeted labeling of an early-stage tumor spheroid in a chorioallantoic membrane model with upconversion nanoparticles
In vivo detection of cancer at an early-stage, i.e. smaller than 2 mm, is a challenge in biomedicine. In this work target labeling of an early-stage tumor spheroid (~500 ÎŒm) is realized for the first time in a chick embryo chorioallantoic membrane (CAM) model with monoclonal antibody functionalized upconversion nanoparticles (UCNPs-mAb).5 page(s
Near Infrared Light Sensitive UltravioletâBlue Nanophotoswitch for Imaging-Guided âOffâOnâ Therapy
Photoswitchable
materials are important in broad applications.
Recently appeared inorganic photoswitchable upconversion nanoparticles
(PUCNPs) become a competitive candidate to surmount the widespread
issue of the organic counterparts îžphotobleaching. However,
current PUCNPs follow solely Yb<sup>3+</sup>/Nd<sup>3+</sup> cosensitizing
mode, which results in complex multilayer doping patterns and imperfectness
of switching in UVâblue region. In this work, we have adopted
a new strategy to construct Nd<sup>3+</sup> free PUCNPsîžNaErF<sub>4</sub>@NaYF<sub>4</sub>@NaYbF<sub>4</sub>:0.5%Tm@NaYF<sub>4</sub>. These PUCNPs demonstrate the superior property of photoswitching.
A prominent UVâblue emission from Tm<sup>3+</sup> is turned
on upon 980 nm excitation, which can be completely turned off by 800
nm light. The quasi-monochromatic red upconversion emission upon 800
nm excitationîža distinct feature of undoping NaErF<sub>4</sub> upconversion systemîžendows the PUCNPs with promising image-guided
photoinduced âoffâonâ therapy in biomedicine.
As a proof-of-concept we have demonstrated the imaging-guided photodynamic
therapy (PDT) of cancer, where 800 nm excitation turns off the UVâblue
emission and leaves the emission at 660 nm for imaging. Once the tumor
site is targeted, excitation switching to 980 nm results in UVâblue
emission and the red emission. The former is used to induce PDT, whereas
the latter is to monitor the therapeutic process. Our study implies
that this upconversion photoswitching material is suitable for real-time
imaging and image-guided therapy under temporal and spatial control
Ultrastrong Absorption Meets Ultraweak Absorption: Unraveling the Energy-Dissipative Routes for Dye-Sensitized Upconversion Luminescence
Dye sensitization
is becoming a new dimension to highly improve
the upconversion luminescence (UCL) of lanthanide-doped upconversion
nanoparticles (UCNPs). However, there is still a lack of general understanding
of the dyeâUCNPs interactions, especially the confused large
mismatch between the inputs and outputs. By taking dye-sensitized
NaYF<sub>4</sub>:Yb/Er@NaYF<sub>4</sub>:Nd UCNPs as a model system,
we not only revealed the in-depth energy-dissipative process for dye-sensitized
UCL but also confirmed the first ever experimental observation of
the energy back transfer (EBT) in the dye-sensitized UCL. Furthermore,
this energy-dissipative EBT restricted the optimal ratio of dyes to
UCNP. By unearthing all of the energy loss behind the EBT, energy
transfer, and energy migration processes, this paper sheds light on
the further design of effective dye-sensitized nanosystems for UCL
or even downconversion luminescence
Covalently Assembled NIR Nanoplatform for Simultaneous Fluorescence Imaging and Photodynamic Therapy of Cancer Cells
A highly efficient multifunctional nanoplatform for simultaneous upconversion luminescence (UCL) imaging and photodynamic therapy has been developed on the basis of selective energy transfer from multicolor luminescent NaYF<sub>4</sub>:Yb<sup>3+</sup>,Er<sup>3+</sup> upconversion nanoparticles (UCNPs) to photosensitizers (PS). Different from popular approaches based on electrostatic or hydrophobic interactions, over 100 photosensitizing molecules were covalently bonded to every 20 nm UCNP, which significantly strengthened the UCNPâPS linkage and reduced the probability of leakage/desorption of the PS. Over 80% UCL was transferred to PS, and the singlet oxygen production was readily detected by its feature emission at 1270 nm. Tests performed on JAR choriocarcinoma and NIH 3T3 fibroblast cells verified the efficient endocytosis and photodynamic effect of the nanoplatform with 980 nm irradiation specific to JAR cancer cells. Our work highlights the promise of using UCNPs for potential image-guided cancer photodynamic therapy
Near infrared light-driven water oxidation in a molecule-based artificial photosynthetic device using an upconversion nano-photosensitizer
We provide the first demonstration of a near infrared light driven water oxidation reaction in a molecule-based artificial photosynthetic device using an upconversion nano-photosensitizer. One very attractive advantage of this system is that using NIR light irradiation does not cause significant photodamage, a serious problem in molecular based artificial photosynthesis under visible light irradiation