Chongna Zhong

Monodisperse bifunctional Fe3O4@NaGdF4:Yb/Er@NaGdF4:Yb/Er core–shell nanoparticles

We report for the first time the synthesis of monodisperse, magnetic and up-conversion luminescent Fe3O4@NaGdF4:Yb/Er@NaGdF4:Yb/Er core–shell structured nanoparticles (NPs) by a seed-growth process. The growth of a NaGdF4:Yb/Er shell on Fe3O4@NaGdF4:Yb/Er NPs can significantly enhance the up-conversion emission intensity.

Facile preparation and fluorescence enhancement of yolk-like Ag@Y2O3:Yb3+,Tm3+ hollow structured composite

A yolk-like Ag@Y2O3:Yb3+,Tm3+ hollow structured composite was prepared through a layer-by-layer technique by coating a carbon layer on Ag seeds and further coating a Y2O3:Yb3+,Tm3+ layer, followed by a subsequent calcination process. The phase, morphology, structure, formation process, and up-conversion properties are well characterized by various techniques. XRD results show that all diffraction peaks of the products are consistent with standard values for the pure cubic phase of Y2O3 and cubic Ag. TEM images demonstrate that the interior space of the composite can be tuned by altering the thickness of the carbon layer. Moreover, the possible evolution mechanism from Ag cores to the final yolk-like structured composite is described. By doping the Yb3+ and Tm3+ ions into the Y2O3 host matrix, these particles show blue (1G4 → 3H6) and near infrared (3H4 → 3H6) emissions with different intensity depending on carbon layer thickness under 980 nm NIR laser excitation. Therefore, this material has potential for application in biomedical fields. In addition, the synthetic route may be of great value in the preparation of other hollow materials.

Au Nanoclusters Sensitized Black TiO2−x Nanotubes for Enhanced Photodynamic Therapy Driven by Near-Infrared Light

The low reactive oxygen species production capability and the shallow tissue penetration of excited light (UV) are still two barriers in photodynamic therapy (PDT). Here, Au cluster anchored black anatase TiO2-x nanotubes (abbreviated as Au25 /B-TiO2-x NTs) are synthesized by gaseous reduction of anatase TiO2 NTs and subsequent deposition of noble metal. The Au25 /B-TiO2-x NTs with thickness of about 2 nm exhibit excellent PDT performance. The reduction process increased the density of Ti3+ on the surface of TiO2 , which effectively depresses the recombination of electron and hole. Furthermore, after modification of Au25 nanoclusters, the PDT efficiency is further enhanced owing to the changed electrical distribution in the composite, which forms a shallow potential well on the metal-TiO2 interface to further hamper the recombination of electron and hole. Especially, the reduction of anatase TiO2 can expend the light response range (UV) of TiO2 to the visible and even near infrared (NIR) light region with high tissue penetration depth. When excited by NIR light, the nanoplatform shows markedly improved therapeutic efficacy attributed to the photocatalytic synergistic effect, and promotes separation or restrained recombination of electron and hole, which is verified by experimental results in vitro and in vivo.

Lanthanide-doped bismuth oxobromide nanosheets for self-activated photodynamic therapy

Low tissue penetration depth of the excited light and complicated synthetic procedures greatly hinder the clinical application of photodynamic therapy (PDT). Here we present a facile and mass production route to fabricate Yb3+/Tm3+ co-doped BiOBr nanosheets. In contrast to the complicated combination of photosensitizers (PSs) with up-conversion nanoparticles (UCNPs), which generates a PDT effect by a fluorescence resonance energy transfer process from UCNPs to PSs upon near-infrared light excitation, this as-synthesized material can be self-activated by deep-penetrating 980 nm laser light to produce a large amount of reactive oxygen species, giving rise to a high PDT efficiency which has been proven by in vitro and in vivo therapeutic assays. Surface modification of the BiOBr:Yb,Tm nanosheets with polyethylene glycol endows the system with improved biocompatibility. Through the combination of inherent fluorescence and CT imaging properties, an imaging-monitored therapeutic system has been realized. The system overcomes the problems of low tissue penetration depth, complicated structure-induced low efficiency, and potential safety concerns. Our finding presents the first demonstration of a self-activated nanoplatform for targeted and noninvasive deep-cancer therapy.

Near-infrared light-induced imaging and targeted anti-cancer therapy based on a yolk/shell structure

To combine photodynamic therapy (PDT) and bio-imaging for improved antitumor efficacy, we design a yolk-like NaYF4:Yb,Er@MgSiO3–ZnPc–RGD mesoporous platform by encapsulating a photosensitive agent (ZnPc) and a targeted peptide, NH2-Gly-Arg-Gly-Asp-Ser (RGD), into MgSiO3 mesoporous shell coated NaYF4:Yb,Er spheres. A novel spinous MgSiO3 shell is synthesized by an in situ growth process without using any surfactant, instead of the conventional mesoporous silica shell. Upon 980 nm laser irradiation, the emitted red light matches well with the absorbance of ZnPc, which generates reactive oxygen species (ROS) to kill cancer cells, and the retained green light allows for real-time monitoring of the therapeutic process. The in vitro and in vivo results indicate that the platform shows excellent anti-cancer therapeutic efficacy under NIR laser irradiation due to the specialised intracellular transition pattern, avoiding premature leakout of ZnPc, and targeted accumulation in the cancer cell sites. Thus, we envision that our proposed platform should have great potential for PDT-induced tumor therapy and for monitoring biochemical changes taking place in live tumor cells.

Glutathione Mediated Size‐Tunable UCNPs‐Pt(IV)‐ZnFe2O4 Nanocomposite for Multiple Bioimaging Guided Synergetic Therapy

Here a multifunctional nanoplatform (upconversion nanoparticles (UCNPs)-platinum(IV) (Pt(IV))-ZnFe2 O4 , denoted as UCPZ) is designed for collaborative cancer treatment, including photodynamic therapy (PDT), chemotherapy, and Fenton reaction. In the system, the UCNPs triggered by near-infrared light can convert low energy photons to high energy ones, which act as the UV-vis source to simultaneously mediate the PDT effect and Fentons reaction of ZnFe2 O4 nanoparticles. Meanwhile, the Pt(IV) prodrugs can be reduced to high virulent Pt(II) by glutathione in the cancer cells, which can bond to DNA and inhibit the copy of DNA. The synergistic therapeutic effect is verified in vitro and in vivo results. The cleavage of Pt(IV) from UCNPs during the reduction process can shift the larger UCPZ nanoparticles (NPs) to the smaller ones, which promotes the enhanced permeability and retention (EPR) and deep tumor penetration. In addition, due to the inherent upconversion luminescence (UCL) and the doped Yb3+ and Fe3+ in UCPZ, this system can serve as a multimodality bioimaging contrast agent, covering UCL, X-ray computed tomography, magnetic resonance imaging, and photoacoustic. A smart all-in-one imaging-guided diagnosis and treatment system is realized, which should have a potential value in the treatment of tumor.

Multifunctional Theranostic Nanoplatform Based on Fe-mTa2O5@CuS-ZnPc/PCM for Bimodal Imaging and Synergistically Enhanced Phototherapy

Multifunctional nanotheranostic agent with high performance for tumor site-specific generation of singlet oxygen (1O2) as well as imaging-guidance is crucial to laser-mediated photodynamic therapy. Here, we introduced a versatile strategy to design a smart nanoplatform using phase change material (PCM) to encapsulate photosensitizer (zinc phthalocyanine, ZnPc) in copper sulfide loaded Fe-doped tantalum oxide (Fe-mTa2O5@CuS) nanoparticles. When irradiated by 808 nm laser, the PCM is melted due to the hyperthermia effect from CuS nanoparticles, inducing the release of ZnPc to produce toxic 1O2 triggered by 650 nm light with very low power density (5 mW/cm2). Then, the produced heat and toxic 1O2 can kill tumor cells in vitro and in vivo effectively. Furthermore, the special properties of Fe-mTa2O5 endow the nanoplatform with excellent computed tomography (CT) and T1-weighted magnetic resonance imaging ( T1-MRI) performance for guiding and real-time monitoring of therapeutic effect. This work presents a feasible way to design smart nanoplatform for controllable generation of heat and 1O2, achieving CT/ T1-MRI dual-modal imaging-guided phototherapy.

Carbon‐Dot‐Decorated TiO2 Nanotubes toward Photodynamic Therapy Based on Water‐Splitting Mechanism

The use of visible light to produce reactive oxygen species (ROS) from renewable water splitting is a highly promising means in photodynamic therapy (PDT). Up to date, diverse inorganic-organic hybrid materials developed as photosensitizers still undergo low therapeutic efficiency and/or poor stability. Herein, a kind of carbon-nanodot-decorated TiO2 nanotubes (CDots/TiO2 NTs) composite is developed and applied for photodynamic therapy. Upon 650 nm laser light excitation, the emissions with short wavelengths (325-425 nm) from the CDots as a result of upconversion process excite TiO2 NTs to form electron/hole (e- /h+ ) pairs, triggering the reaction with the adsorbed oxidants to produce ROS. Moreover, the CDots deposited on the surface of TiO2 NTs markedly enhance the light absorption response and narrow the band gap compared with anatase TiO2 nanoparticles, thereby increasing the photosensitizing efficiency. Besides, the CDots show high chemical catalytic activity for H2 O2 decomposition even if no light is needed, which is essential for PDT. The excellent therapeutic performance actuated by 650 nm light is demonstrated by in vitro and in vivo assays. This photosensitizer comprises low-cost, earth-abundant, environment-friendly merits, and especially excellent stability, implying its feasible application in biomedical field.