Ultra-wideband-responsive photon conversion through co-sensitization in lanthanide nanocrystals.

Distinctive upconversion or downshifting of lanthanide nanocrystals holds promise for biomedical and photonic applications. However, either process requires high-energy lasers at discrete wavelengths for excitation. Here we demonstrate that co-sensitization can break this limitation with ultrawide excitation bands. We achieve co-sensitization by employing Nd3+ and Ho3+ as the co-sensitizers with complementary absorptions from the ultraviolet to infrared region. Symmetric penta-layer core-shell nanostructure enables tunable fluorescence in the visible and the second near-infrared window when incorporating different activators (Er3+, Ho3+, Pr3+, and Tm3+). Transient spectra confirm the directional energy transfer from sensitizers to activators through the bridge of Yb3+. We validate the features of the nanocrystals for low-powered white light-emitting diode-mediated whole-body angiography of mice with a signal-to-noise ratio of 12.3 and excitation-regulated encryption. This co-sensitization strategy paves a new way in lanthanide nanocrystals for multidirectional photon conversion manipulation and excitation-bandwidth-regulated fluorescence applications.

Recent Progress and Trends in X-ray-Induced Photodynamic Therapy with Low Radiation Doses.

The prominence of photodynamic therapy (PDT) in treating superficial skin cancer inspires innovative solutions for its congenitally deficient shadow penetration of the visible-light excitation. X-ray-induced photodynamic therapy (X-PDT) has been proven to be a successful technique in reforming the conventional PDT for deep-seated tumors by creatively utilizing penetrating X-rays as external excitation sources and has witnessed rapid developments over the past several years. Beyond the proof-of-concept demonstration, recent advances in X-PDT have exhibited a trend of minimizing X-ray radiation doses to quite low values. As such, scintillating materials used to bridge X-rays and photosensitizers play a significant role, as do diverse well-designed irradiation modes and smart strategies for improving the tumor microenvironment. Here in this review, we provide a comprehensive summary of recent achievements in X-PDT and highlight trending efforts using low doses of X-ray radiation. We first describe the concept of X-PDT and its relationships with radiodynamic therapy and radiotherapy and then dissect the mechanism of X-ray absorption and conversion by scintillating materials, reactive oxygen species evaluation for X-PDT, and radiation side effects and clinical concerns on X-ray radiation. Finally, we discuss a detailed overview of recent progress regarding low-dose X-PDT and present perspectives on possible clinical translation. It is expected that the pursuit of low-dose X-PDT will facilitate significant breakthroughs, both fundamentally and clinically, for effective deep-seated cancer treatment in the near future.

Antiangiogenesis Combined with Inhibition of the Hypoxia Pathway Facilitates Low-Dose, X-ray-Induced Photodynamic Therapy.

X-ray-induced photodynamic therapy (XPDT) is overwhelmingly superior in treating deep-seated cancers. However, limitations remain, owing to a combination of the poor scintillation performance of the nanoscintillator, low energy transfer efficiency of the therapeutic nanoplatform, and hypoxic environment presented in the tumor tissue. Collectively, these reduce the curative effect of XPDT. Here, we report a highly efficient, low-dose XPDT realized by systematic optimization from scintillation efficiency, nanoplatform structure, to therapeutic approach. We developed a biocompatible, codoped CaF2 nanoscintillator that emitted sufficiently green radioluminescence that was bright enough to be seen by the naked eye. Using dendrimers as a framework, we built a nanoplatform featuring a dual-core-satellite architecture, which enabled both procedurally and spatially separate dual-loading of therapeutic agents. This strategy allowed for the fabrication of a combined XPDT and antiangiogenic therapy, resulting in a therapeutic system capable of simultaneous tumor attacks. After exposure to ultralow dose radiation, XPDT resulted in marked tumor reduction while the antiangiogenic drug effectively blocked tumor vascularization exacerbated by XPDT-mediated hypoxia, rendering a pronounced synergy effect. This system also showed high biosafety, as the agents adopted had been used clinically and both Ca and F elements were widespread in the human body. Taken together, the findings presented here provided a reference for the construction of complex, multiloading architecture in coordination with structural complexity and functional diversification. This work provided a safer and more robust application of the combined XPDT and antiangiogenesis in future clinical treatment settings.

Reduced Local Symmetry in Lithium Compound Li2SrSiO4 Distinguished by an Eu3+ Spectroscopy Probe.

Research on lithium compounds has attracted much attention nowadays. However, to elucidate the precise structure of lithium compounds is a challenge, especially when considering the small ions that may be transferred between the interstitial voids. Here, the discovery of reduced local symmetry (symmetry breaking) in small domains of Li2SrSiO4 is reported by employing Eu3+ as a spectroscopic probe, for which X-ray, neutron, and electron diffraction have confirmed the average long-range structure with the space group P3121. However, luminescence shows a lower local symmetry, as confirmed by the extended X-ray absorption fine structure. By considering the reduced symmetry of the local structure, this work opens the door to a new class of understanding of the properties of materials.

Dataset of emission and excitation spectra, UV-vis absorption spectra, and XPS spectra of graphitic C3N4.

In this data article, the normalized emission and excitation spectra, the ultraviolet-visible (UV-vis) absorption spectra, and the X-ray photoelectron spectroscopy (XPS) of bulk-powders and nano-structured graphitic C3N4 (g-C3N4) were presented, which are helpful to get insight into the crystal and electronic structures of g-C3N4, especially on determining the energy levels and the mechanisms of luminescence originating from electron transitions. This data article is related to our recent publication (He et al., in press) [1]. The absorption, excitation and emission spectra are vital to illustrate the optoelectronic performances in terms of photoluminescence, photocatalysis, electroluminescence, etc., from the viewpoint of electron transitions intrinsically.