Upconversion nanoparticle as a theranostic agent for tumor imaging and therapy

Upconversion nanoparticles(UCNPs)as a promising material are widely studied due to their unique optical properties.The material can be excited by long w avelength light and emit visible wavelength light through multiphoton absorption.This property makes the particles highly attractive candidates for bioimaging and therapy application.This review aims at summarizing the synthesis and modification of UCNPs,especially the applications of UCNPs as a theranostic agent for tumor imaging and therapy.The biocompatibility and toxicity of UCNPs are also further discussed.Finally,we discuss the challenges and opportunities in the development of UCNP-based nanoplatforms for tumor imaging and therapy.

10BaF_2:NaF,Na_3AlF_6/TiO_2 composite as a novel visible-light-driven photocatalyst based on upconversion emission

A rare-earth free upconversion luminescent material, 10BaF2：NaF, Na3AIF6, is synthesized by a hydrothermal method. The study of fluorescent spectrum indicates that it can convert visible light （550 nm-610 nm） into ultraviolet light （290 nm 350 nm）, and two emission peaks at 304 nm and 324 nm are observed under the excitation of 583 nm at room temperature. Subsequently, 10BaF2：NaF, Na3AIF6/TiO2 composite photocatalyst is prepared and its catalytic activity is evaluated by the photocatalytic reduction of CO2 under visible light irradiation （λ〉 515 nm）. The results show that 10BaF2：NaF, Na3AIF6/TiO2 is a more effective photocatalyst for CO2 reduction than pure TiO2, their corresponding methanol yields are 179 and 0 μmol/g-cat under the same conditions. Additionally, the mechanism of photocatalytic reduction of CO2 on 10BaF2：NaF, Na3AIF6/TiO2 is proposed.

Spatiotemporal regulation of ubiquitin-mediated protein degradation via upconversion optogenetic nanosystem

Protein degradation technology,which is one of the most direct and effective ways to regulate the life activities of cells,is expected to be applied to the treatment of various diseases.However,current protein degradation technologies such as some small-molecule degraders which are unable to achieve spatiotemporal regulation,making them difficult to transform into clinical applications.In this article,an upconversion optogenetic nanosystem was designed to attain accurate regulation of protein degradation.This system worked via two interconnected parts:1)the host cell expressed light-sensitive protein that could trigger the ubiquitinproteasome pathway upon blue-light exposure;2)the light regulated light-sensitive protein by changing light conditions to achieve regulation of protein degradation.Experimental results based on model protein(Green Fluorescent Protein,GFP)validated that this system could fulfill protein degradation both in vitro(both Hela and 293T cells)and in vivo(by upconversion optogenetic nanosystem),and further demonstrated that we could reach spatiotemporal regulation by changing the illumination time(0–25 h)and the illumination frequency(the illuminating frequency of 0–30 s every 1 min).We further took another functional protein(The Nonstructural Protein 9,NSP9)into experiment.Results confirmed that the proliferation of porcine reproductive and respiratory syndrome virus(PRRSV)was inhibited by degrading the NSP9 in this light-induced system,and PRRSV proliferation was affected by different light conditions(illumination time varies from 0–24 h).We expected this system could provide new perspectives into spatiotemporal regulation of protein degradation and help realize the clinical application transformation for treating diseases of protein degradation technology.

Enhanced near-infrared light-induced photoresponse via transition of monocrystalline phase and surface reconstruction

Rare-earth-doped upconversion(UC)materials are ideal candidates for solar photovoltaic conversion and NIR response devices due to their unique spectral conversion properties.However,their low efficiency remains a tremendous challenge for practical applications.Here,we constructed an efficient NIR light-responsive device by coating a Si-photoresistor with a transparent gel consisting of UC powders and an organic polymer matrix.We show that reasonable introduction of alkali metal ions(Na~+,K~+,and Cs~+)into the lattice of UC crystals results in the improvement of photoelectricity conversion efficiency,due to the high crystallinity and surface reconstruction caused by alkali metal ion doping.