Amorphization of MXenes: Boosting Electrocatalytic Hydrogen Evolution

The emergence of amorphous 2D materials has opened up new avenue for materials science and nanotechnology in the recent years. Their unique disordered structure, excellent large-area uniformity, and low fabrication cost make them important for various industrial applications. However, there have no reports on the amorphous MXene materials. In this work, the amorphous Ti2C-MXene (a-Ti2C-MXene) model is built by ab initio molecular dynamics (AIMD) approach. This model is a unique amorphous model, which is totally different from continuous random network (CRN) model for silicate glass and amorphous model for amorphous 2D BN and graphene. The structure analysis shows that the a-Ti2C-MXene composited by [Ti5C] and [Ti6C] cluster, which are surrounded by the region of mixed cluster [TixC], [Ti-Ti] cluster, and [C-C] cluster. There is a high chemical activity for hydrogen evolution reaction (HER) in a-Ti2C-MXene with |ΔGH| 0.001 eV, implying that they serve as the potential boosting HER performance. The work provides insights that can pave the way for future research on novel MXene materials, leading to their increased applications in various fields.

Self-Heating Multistage Microneedle Patch for Topical Therapy of Skin Cancer

Topical therapy is a favored route for treating skin cancers, but remain many challenges, such as low delivery efficiency, limited tumor tissue penetration, and unsatisfactory blood circulation. Here, a self-heating microneedle (MN) patch with multilevel structures, including a dissolvable base for rapid drug release, a degradable tip for sustained drug release, and a self-heating substrate is described. The thermally enhanced drug release performance is validated through both in vitro and in vivo experiments. High tumor therapeutic efficacy can be achieved due to the rapid release of 5-fluorouracil, while the sustained release of thymoquinone endows the MN patch with long-term tumor inhibition ability. It is further demonstrated the feasibility of such an MN patch for in vivo topical therapy of cutaneous squamous cell carcinoma with high efficacy, low side effects, and long-term inhibition of recurrence. This self-heating MN patch holds great promise for potential clinical applications, especially for the treatment of skin cancers.

Biosynthesis of NIR-II Ag2 Se Quantum Dots with Bacterial Catalase for Photoacoustic Imaging and Alleviating-Hypoxia Photothermal Therapy

Developing the second near-infrared (NIR-II) photoacoustic (PA) agent is of great interest in bioimaging. Ag2 Se quantum dots (QDs) are one kind of potential probe for applications in NIR-II photoacoustic imaging (PAI). However, the surfaces with excess anions of Ag2 Se QDs, which increase the probability of nonradiative transitions of excitons benefiting PA imaging, are not conducive to binding electron donor ligands for potential biolabeling and imaging. In this study, Staphylococcus aureus (S. aureus) cells are driven for the biosynthesis of Ag2 Se QDs with catalase (CAT). Biosynthesized Ag2 Se (bio-Ag2 Se-CAT) QDs are produced in Se-enriched environment of S. aureus and have a high Se-rich surface. The photothermal conversion efficiency of bio-Ag2 Se-CAT QDs at 808 and 1064 nm is calculated as 75.3% and 51.7%, respectively. Additionally, the PA signal responsiveness of bio-Ag2 Se-CAT QDs is ≈10 times that of the commercial PA contrast agent indocyanine green. In particular, the bacterial CAT is naturally attached to bio-Ag2 Se-CAT QDs surface, which can effectively relieve tumor hypoxia. The bio-Ag2 Se-CAT QDs can relieve heat-initiated oxidative stress while undergoing effective photothermal therapy (PTT). Such biosynthesis method of NIR-II bio-Ag2 Se-CAT QDs opens a new avenue for developing multifunctional nanomaterials, showing great promise for PAI, hypoxia alleviation, and PTT.

Shear stiffening gel-enabled twisted string for bio-inspired robot actuators

A rotary motor combined with fibrous string demonstrates excellent performance because it is powerful, lightweight, and prone to large strokes; however, the stiffness range and force-generating capability of twisted string transmission systems are limited. Here, we present a variable stiffness artificial muscle generated by impregnating shear stiffening gels (STGs) into a twisted string actuator (TSA). A high twisting speed produces a large impact force and causes shear stiffening of the STG, thereby improving the elasticity, stiffness, force capacity, and response time of the TSA. We show that at a twisting speed of 4186 rpm, the elasticity of an STG-TSA reached 30.92 N/mm, whereas at a low twisting speed of 200 rpm, it was only 10.51 N/mm. In addition, the STG-TSA exhibited a more prominent shear stiffening effect under a high stiffness load. Our work provides a promising approach for artificial muscles to coactivate with human muscles to effectively compensate for motion.

Trophoblast-derived miR-410-5p induces M2 macrophage polarization and mediates immunotolerance at the fetal-maternal interface by targeting the STAT1 signaling pathway

BACKGROUND

Macrophages phenotypic deviation and immune imbalance play vital roles in pregnancy-associated diseases such as spontaneous miscarriage. Trophoblasts regulate phenotypic changes in macrophages, however, their underlying mechanism during pregnancy remains unclear. Therefore, this study aimed to elucidate the potential function of trophoblast-derived miRNAs (miR-410-5p) in macrophage polarization during pregnancy.

METHODS

Patient decidual macrophage tissue samples in spontaneous abortion group and normal pregnancy group (those who had induced abortion for non-medical reasons) were collected at the Reproductive Medicine Center of Renmin Hospital of Wuhan University from April to December 2021. Furthermore, placental villi and decidua tissue samples were collected from patients who had experienced a spontaneous miscarriage and normal pregnant women for validation and subsequent experiments at the Shenzhen Zhongshan Obstetrics & Gynecology Hospital (formerly Shenzhen Zhongshan Urology Hospital), from March 2021 to September 2022. As an animal model, 36 female mice were randomly divided into six groups as follows: naive-control, lipopolysaccharide-model, agomir-negative control prevention, agomir-410-5p prevention, agomir-negative control treatment, and agomir-410-5p treatment groups. We analyzed the miR-410-5p expression in abortion tissue and plasma samples; and supplemented miR-410-5p to evaluate embryonic absorption in vivo. The main source of miR-410-5p at the maternal-fetal interface was analyzed, and the possible target gene, signal transducer and activator of transcription (STAT) 1, of miR-410-5p was predicted. The effect of miR-410-5p and STAT1 regulation on macrophage phenotype, oxidative metabolism, and mitochondrial membrane potential was analyzed in vitro.

RESULTS

MiR-410-5p levels were lower in the spontaneous abortion group compared with the normal pregnancy group, and plasma miR-410-5p levels could predict pregnancy and spontaneous abortion. Prophylactic supplementation of miR-410-5p in pregnant mice reduced lipopolysaccharide-mediated embryonic absorption and downregulated the decidual macrophage pro-inflammatory phenotype. MiR-410-5p were mainly distributed in villi, and trophoblasts secreted exosomes-miR-410-5p at the maternal-fetal interface. After macrophages captured exosomes, the cells shifted to the tolerance phenotype. STAT1 was a potential target gene of miR-410-5p. MiR-410-5p bound to STAT1 mRNA, and inhibited the expression of STAT1 protein. STAT1 can drive macrophages to mature to a pro-inflammatory phenotype. MiR-410-5p competitive silencing of STAT1 can avoid macrophage immune disorders.

CONCLUSION

MiR-410-5p promotes M2 macrophage polarization by inhibiting STAT1, thus ensuring a healthy pregnancy. These findings are of great significance for diagnosing and preventing spontaneous miscarriage, providing a new perspective for further research in this field.

Development and performance of SIAT bPET: a high-resolution and high-sensitivity MR-compatible brain PET scanner using dual-ended readout detectors

PURPOSE

Positron emission tomography/magnetic resonance imaging (PET/MRI) is a powerful tool for brain imaging, but the spatial resolution of the PET scanners currently used for brain imaging can be further improved to enhance the quantitative accuracy of brain PET imaging. The purpose of this study is to develop an MR-compatible brain PET scanner that can simultaneously achieve a uniform high spatial resolution and high sensitivity by using dual-ended readout depth encoding detectors.

METHODS

The MR-compatible brain PET scanner, named SIAT bPET, consists of 224 dual-ended readout detectors. Each detector contains a 26 × 26 lutetium yttrium oxyorthosilicate (LYSO) crystal array of 1.4 × 1.4 × 20 mm3 crystal size read out by two 10 × 10 silicon photomultiplier (SiPM) arrays from both ends. The scanner has a detector ring diameter of 376.8 mm and an axial field of view (FOV) of 329 mm. The performance of the scanner including spatial resolution, sensitivity, count rate, scatter fraction, and image quality was measured. Imaging studies of phantoms and the brain of a volunteer were performed. The mutual interferences of the PET insert and the uMR790 3 T MRI scanner were measured, and simultaneous PET/MRI imaging of the brain of a volunteer was performed.

RESULTS

A spatial resolution of better than 1.5 mm with an average of 1.2 mm within the whole FOV was obtained. A sensitivity of 11.0% was achieved at the center FOV for an energy window of 350-750 keV. Except for the dedicated RF coil, which caused a ~ 30% reduction of the sensitivity of the PET scanner, the MRI sequences running had a negligible effect on the performance of the PET scanner. The reduction of the SNR and homogeneity of the MRI images was less than 2% as the PET scanner was inserted to the MRI scanner and powered-on. High quality PET and MRI images of a human brain were obtained from simultaneous PET/MRI scans.

CONCLUSION

The SIAT bPET scanner achieved a spatial resolution and sensitivity better than all MR-compatible brain PET scanners developed up to date. It can be used either as a standalone brain PET scanner or a PET insert placed inside a commercial whole-body MRI scanner to perform simultaneous PET/MRI imaging.

A 3D-Printed Ferromagnetic Liquid Crystal Elastomer with Programmed Dual-Anisotropy and Multi-Responsiveness

Liquid crystal elastomers (LCE) and magnetic soft materials are promising active materials in many emerging fields, such as soft robotics. Despite the high demand for developing active materials that combine the advantages of LCE and magnetic actuation, the lack of independent programming of the LCE nematic order and magnetization in a single material still hinders the desired multi-responsiveness. In this study, a ferromagnetic LCE (magLCE) ink with nematic order and magnetization is developed that can be independently programmed to be anisotropic, referred to as "dual anisotropy", via a customized 3D-printing platform. The magLCE ink is fabricated by dispersing ferromagnetic microparticles in the LCE matrix, and a 3D-printing platform is created by integrating a magnet with 3-DoF motion into an extrusion-based 3D printer. In addition to magnetic fields, magLCEs can also be actuated by heating sources (either environmental heating or photo-heating of the embedded ferromagnetic microparticles) with a high energy density and tunable actuation temperature. A programmed magLCE strip robot is demonstrated with enhanced adaptability to complex environments (different terrains, magnetic fields, and temperatures) using a multi-actuation strategy. The magLCE also has potential applications in mechanical memory, as demonstrated by the multistable mechanical metastructure array with remote writability and stable memory.

Mechanically-Compliant Bioelectronic Interfaces through Fatigue-Resistant Conducting Polymer Hydrogel Coating

Because of their distinct electrochemical and mechanical properties, conducting polymer hydrogels have been widely exploited as soft, wet, and conducting coatings for conventional metallic electrodes, providing mechanically compliant interfaces and mitigating foreign body responses. However, the long-term viability of these hydrogel coatings is hindered by concerns regarding fatigue crack propagation and/or delamination caused by repetitive volumetric expansion/shrinkage during long-term electrical interfacing. This study reports a general yet reliable approach to achieving a fatigue-resistant conducting polymer hydrogel coating on conventional metallic bioelectrodes by engineering nanocrystalline domains at the interface between the hydrogel and metallic substrates. It demonstrates the efficacy of this robust, biocompatible, and fatigue-resistant conducting hydrogel coating in cardiac pacing, showcasing its ability to effectively reduce the pacing threshold voltage and enhance the long-term reliability of electric stimulation. This study findings highlight the potential of its approach as a promising design and fabrication strategy for the next generation of seamless bioelectronic interfaces.

Tuning the Organ Tropism of Polymersome for Spleen-Selective Nanovaccine Delivery to Boost Cancer Immunotherapy

The past few decades have witnessed explosive development in drug delivery systems. However, in vivo delivery suffers from non-specific distribution in non-targeted organs or tissues, which may cause undesired side effects and even genotoxicity. Here, a general strategy that enables tuning the tropism of polymersomes for liver- and spleen-selective delivery is reported. By using a library screening approach, spleen-targeted polymersome PH9-Aln-8020 and liver-targeted polymersome PA9-ZP3-5050 are identified accordingly. Meanwhile, the second near-infrared (NIR-II) fluorescence imaging allows for in vivo dynamic evaluation of their spatial and temporal accumulation in specific tissues. O ur findings indicate that both polymer composition and protein corona on the surface are essential to determine the in vivo fate of polymersomes and tendency for specific organs. Importantly, PH9-Aln-8020 is employed as a systemic nanocarrier to co-deliver the antigen and adjuvant, which remarkably boost splenic immune responses in acute myeloid leukemia, melanoma, and melanoma lung metastasis mouse models. This study may open a new frontier for polymersomes in organ-selective delivery and other biomedical applications.

Maximum Emission Peak Over 1500 nm of Organic Assembly for Blood-Brain Barrier-Crossing NIR-IIb Phototheranostics of Orthotopic Glioblastoma

The development of blood-brain barrier (BBB)-crossing phototheranostic agents in second near-infrared window (NIR-II), especially in the range of 1500-1700 nm (NIR-IIb), affords great opportunities for glioblastoma (GBM) management. Herein, an organic assembly (denoted as LET-12) with the maximum absorption peak at 1400 nm and emission peak at 1512 nm with trailing over 1700 nm through the self-assembly of organic small molecule IR-1064 is designed and subsequently decorated with choline and acetylcholine analogs. The LET-12 can effectively cross BBB through the brain's choline-like receptors-mediated transcytosis and accumulated in tumor tissues, thus achieving fluorescence/photoacoustic (FL/PA) duplex imaging of orthotopic GBM with ≈3.0 mm depth and a superior tumor-to-normal tissue signal ratio (20.93 ± 0.59 for FL imaging and 32.63 ± 1.16 for PA imaging, respectively). Owing to its good photothermal conversion ability, the LET-12 also can serve as a photothermal conversion agent, achieving obvious tumor repression of orthotopic murine GBM model after once treatment. The findings indicate that the LET-12 holds great potential for BBB-crossing NIR-IIb phototheranostics of orthotopic GBM. This self-assembly strategy of organic small molecules opens a new avenue for the construction of NIR-IIb phototheranostics.

Amorphous MXene Opens New Perspectives

Recently, novel amorphous nanomaterials formed by introducing atomic irregular arrangement factors have been successfully fabricated, showing superior performance in catalysis, energy storage, and mechanics. Among them, 2D amorphous nanomaterials are the stars, as they combine the benefits of both 2D structure and amorphous. Up to now, many research studies have been published on the study of 2D amorphous materials. However, as one of the most important parts of 2D materials, the research on MXenes mainly focuses on the crystalline counterpart, while the study of highly disordered forms is much less. This work will provide insight into the possibility of MXenes amorphization, and discusses the application prospect of amorphous MXenes materials.

Precision Delivery of Dual Immune Inhibitors Loaded Nanomodulator to Reverse Immune Suppression for Combinational Photothermal-Immunotherapy

Although photothermal therapy (PTT) can noninvasively kill tumor cells and exert synergistic immunological effects, the immune responses are usually harmed due to the lack of cytotoxic T cells (CTLs) pre-infiltration and co-existing of intricate immunosuppressive tumor microenvironment (TME), including the programmed cell death ligand 1 (PD-L1)/cluster of differentiation 47 (CD47)/regulatory T cells (Tregs)/M2-macrophages overexpression. Indoleamine 2, 3-dioxygenase inhibitor (NLG919) or bromodomain extra-terminal inhibitor (OTX015) holds great promise to reprogram suppressive TME through different pathways, but their collaborative application remains a formidable challenge because of the poor water solubility and low tumor targeting. To address this challenge, a desirable nanomodulator based on dual immune inhibitors loaded mesoporous polydopamine nanoparticles is designed. This nanomodulator exhibits excellent biocompatibility and water solubility, PTT, and bimodal magnetic resonance/photoacoustic imaging abilities. Owing to enhanced permeability and retention effect and tumor acidic pH-responsiveness, both inhibitors are precisely delivered and locally released at tumor sites. Such a nanomodulator significantly reverses the immune suppression of PD-L1/CD47/Tregs, promotes the activation of CTLs, regulates M2-macrophages polarization, and further boosts combined therapeutic efficacy, inducing a strong immunological memory. Taken together, the nanomodulator provides a practical approach for combinational photothermal-immunotherapy, which may be further broadened to other "immune cold" tumors.

Lactate-Oxidase-Instructed Cancer Diagnosis and Therapy

Lactate oxidase (LOx) has attracted extensive interest in cancer diagnosis and therapy in recent years owing to its specific catalysis on l-lactate; its catalytic process consumes oxygen (O₂ ) and generates a large amount of hydrogen peroxide (H₂ O₂ ) and pyruvate. Given high levels of lactate in tumor tissues and its tight correlation with tumor growth, metastasis, and recurrence, LOx-based biosensors including H₂ O₂ -based, O₂ -based, pH-sensitive, and electrochemical have been designed for cancer diagnosis, and various LOx-based cancer therapy strategies including lactate-depletion-based metabolic cancer therapy/immunotherapy, hypoxia-activated chemotherapy, H₂ O₂ -based chemodynamic therapy, and multimodal synergistic cancer therapy have also been developed. In this review, the lactate-specific catalytic properties of LOx are introduced, and the recent advances on LOx-instructed cancer diagnostic or therapeutic platforms and corresponding biological applications are summarized. Additionally, the challenges and potential of LOx-based nanomedicines are highlighted.

Programmably Controllable Delivery of Metastable Ferrous Ions for Multiscale Dynamic Imaging Guided Photothermal Primed Chemodynamic Therapy

Metallomodulation cell death strategies are extensively investigated for antitumor therapy, such as cuproptosis, ferroptosis, and chemodynamic therapy (CDT). Undoubtedly, the accurate and specific elevation of metal ions levels in cancer cells is key to boosting their therapeutic index. Herein, a programmably controllable delivery system based on croconium dye (Croc)-ferrous ion (Fe²⁺ ) nanoprobes (CFNPs) is developed for multiscale dynamic imaging guided photothermal primed CDT. The Croc, with kinds of electron-rich iron-chelating groups, can form the Croc-Fe²⁺ complex with a precise stoichiometry of 1:1 to steadily maintain the valence state of Fe²⁺ . The CFNPs can achieve pH-responsive visualization and accurate Fe²⁺ release in cancerous tissues under the coactivation of "dual-key" stimulation of "acidity and near-infrared (NIR) light". The acidic tumor microenvironment actuates NIR fluorescence/photoacoustic imaging and photothermal properties of CFNPs. Sequentially, under exogenous NIR light, the CFNPs enable in vivo accurate visualization of Croc-Fe²⁺ complex delivery for photothermal primed Fe²⁺ release, thus achieving CDT of tumors. By leveraging multiscale dynamic imaging technologies, the complicated spatiotemporal release of Fe²⁺ is sketched in a programmably controllable manner, and the domino effect of tumor pH level, photothermal effect, and CDT is also revealed, endowing customized feedback of the therapeutic panorama within the disease microenvironment.

Highly NH3 Sensitive and Selective Ti3C2O2-Based Gas Sensors: A Density Functional Theory-NEGF Study

Ammonia (NH₃) detection at the early stage is an important precaution for human health and agricultural production. However, conventional sensing materials are difficult to achieve all the targeted operational performances such as low power consumption and high selectivity. MXenes are a type of graphene-like emergent material equipped with abundant surface sites benefiting gas-sensing applications. In the work, we discuss the sensing performance of Ti₃C₂O₂ to anticipate harmful and polluting NH₃ gases by density functional theory and nonequilibrium Green's function. The adsorption geometry, charge difference density, and partial density of states are discussed to understand the nature of interactions between gas molecules and Ti₃C₂O₂. The theoretical results show that only NH₃ adsorbs onto the nanosheet through chemisorption. Then, a two-electrode Ti₃C₂O₂-based gas sensor device is built to unravel the transport properties. Current under different bias voltages indicates the Ti₃C₂O₂-based sensor could maintain extremely high sensitivity, demonstrating that Ti₃C₂O₂ has great potential for the NH₃ sensor with high selectivity, excellent sensitivity, and low energy consumption. Upon external electric fields, the adsorption energy and charge transfer can be tuned effectively, suggesting that Ti₃C₂O₂ is a versatile agent as an ammonia-sensing material.

SelfCoLearn: Self-Supervised Collaborative Learning for Accelerating Dynamic MR Imaging

Lately, deep learning technology has been extensively investigated for accelerating dynamic magnetic resonance (MR) imaging, with encouraging progresses achieved. However, without fully sampled reference data for training, the current approaches may have limited abilities in recovering fine details or structures. To address this challenge, this paper proposes a self-supervised collaborative learning framework (SelfCoLearn) for accurate dynamic MR image reconstruction from undersampled k-space data directly. The proposed SelfCoLearn is equipped with three important components, namely, dual-network collaborative learning, reunderampling data augmentation and a special-designed co-training loss. The framework is flexible and can be integrated into various model-based iterative un-rolled networks. The proposed method has been evaluated on an in vivo dataset and was compared to four state-of-the-art methods. The results show that the proposed method possesses strong capabilities in capturing essential and inherent representations for direct reconstructions from the undersampled k-space data and thus enables high-quality and fast dynamic MR imaging.

In-situ TiO2-x decoration of titanium carbide MXene for photo/sono-responsive antitumor theranostics

BACKGROUND

Sonodynamic therapy (SDT) has emerged as a noninvasive therapeutic modality that involves sonosensitizers and low-intensity ultrasound. However, owing to the rapid recombination of charge carriers, most of the sonosensitizers triggered poor reactive oxygen species (ROS) generation, resulting in unsatisfactory sonodynamic therapeutic effects.

RESULTS

Herein, a photo/sono-responsive nanoplatform was developed through the in-situ systhesis of TiO2-x on the surface of two-dimensional MXene (titanium carbide, Ti3C2) for photoacoustic/photothermal bimodal imaging-guided near-infrared II (NIR-II) photothermal enhanced SDT of tumor. Because of several oxygen vacancies and smaller size (~ 10 nm), the in-situ formed TiO2-x nanoparticles possessed narrow band gap (2.65 eV) and high surface area, and thus served as a charge trap to restrict charge recombination under ultrasound (US) activation, resulting in enhanced sonodynamic ROS generation. Moreover, Ti3C2 nanosheets induced extensive localized hyperthermia relieves tumor hypoxia by accelerating intratumoral blood flow and tumor oxygenation, and thus further strengthened the efficacy of SDT. Upon US/NIR-II laser dual-stimuli, Ti3C2@TiO2-x nanoplatform triggered substantial cellular killing in vitro and complete tumor eradication in vivo, without any tumor recurrence and systemic toxicity.

CONCLUSION

Our work presents the promising design of photo/sono-responsive nanoplatform for cancer nanotheranostics.

Inorganic Nanomaterials with Intrinsic Singlet Oxygen Generation for Photodynamic Therapy

Inorganic nanomaterials with intrinsic singlet oxygen (1 O2 ) generation capacity, are emerged yet dynamically developing materials as nano-photosensitizers (NPSs) for photodynamic therapy (PDT). Compared to previously reported nanomaterials that have been used as either carriers to load organic PSs or energy donors to excite the attached organic PSs through a Foster resonance energy transfer process, these NPSs possess intrinsic 1 O2 generation capacity with extremely high 1 O2 quantum yield (e.g., 1.56, 1.3, 1.26, and 1.09) than any classical organic PS reported to date, and thus are facilitating to make a revolution in PDT. In this review, the recent advances in the development of various inorganic nanomaterials as NPSs, including metal-based (gold, silver, and tungsten), metal oxide-based (titanium dioxide, tungsten oxide, and bismuth oxyhalide), metal sulfide-based (copper and molybdenum sulfide), carbon-based (graphene, fullerene, and graphitic carbon nitride), phosphorus-based, and others (hybrids and MXenes-based NPSs) are summarized, with an emphasis on the design principle and 1 O2 generation mechanism, and the photodynamic therapeutic performance against different types of cancers. Finally, the current challenges and an outlook of future research are also discussed. This review may provide a comprehensive account capable of explaining recent progress as well as future research of this emerging paradigm.

3D Printed Wesselsite Nanosheets Functionalized Scaffold Facilitates NIR-II Photothermal Therapy and Vascularized Bone Regeneration

Various bifunctional scaffolds have recently been developed to address the reconstruction of tumor-initiated bone defects. Such scaffolds are usually composed of a near-infrared (NIR) photothermal conversion agent and a conventional bone scaffold for photothermal therapy (PTT) and long-term bone regeneration. However, the reported photothermal conversion agents are mainly restricted to the first biological window (NIR-I) with intrinsic poor tissue penetration depth. Also, most of these agents are non-bioactive materials, which induced potential systemic side toxicity after implantation. Herein, a NIR-II photothermal conversion agent (Wesselsite [SrCuSi4 O10 ] nanosheets, SC NSs) with tremendous osteogenic and angiogenic bioactivity, is rationally integrated with polycaprolactone (PCL) via 3D printing. The as-designed 3D composite scaffolds not only trigger osteosarcoma ablation through NIR-II light generated extensive hyperthermia, but also promote in vitro cellular proliferation and osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) and human umbilical vein endothelial cells (HUVECs), respectively, and the ultimate enhancement of vascularized bone regeneration in vivo owing to the controlled and sustained release of bioactive ions (Sr, Cu, and Si). The authors' study provides a new avenue to prepare multifunctional bone scaffolds based on therapeutic bioceramics for repairing tumor-induced bone defects.

An Insight into the Effects of SnF2 Assisting the Performance of Lead-Free Perovskite of FASnI3: A First-Principles Calculations

It is an effective method to use SnF2 and SnF4 molecules to assist in enhancing the performance of FASnI3 perovskite. However, the mechanism in this case is not clear as it lacks a certain explanation to specify the phenomenon. Through first-principles calculations, this paper constructed several modes of SnF2 and SnF4 adsorbed on the surfaces of FASnI3 and explored adsorption energies, band structures, photoelectric properties, absorption spectra, and dielectric functions. The SnF2 molecule adsorbed at the I5 position on the FAI-T surface has the lowest adsorption energy for the F atom, which is 0.5376 eV. The Sn-I bond and Sn-F bond mainly affect the photoelectric properties of FASnI3 perovskite solar cells, and the SnF2 adsorption on the FAI-T surface can effectively strengthen the bond energies, which shortens the bond lengths of the Sn-I and Sn-F bond, and eliminate surface unsaturated bonds to passivate the surface defects. Furthermore, the probability of energy transfer was lower between the SnF2 molecule and the ion around it than between SnF4 and its ion. Especially, in the aspect of optical properties, we found that the intensity of the absorption peak of SnF2 adsorption increase was larger than that of SnF4 adsorption. Additionally, the static dielectric constants of SnF4 adsorption on the two surfaces, denoted SnF4, made the perovskite respond more slowly to the external electric field. Based on this work, we found that SnF2 had a greater positive effect on the optical property of perovskite than SnF4. We consider that our results can help to deeply understand the essence of SnF2 assistance in the performance of FASnI3 and help researchers strive for lead-free perovskite solar cells.

Improving the Catalytic CO2 Reduction on Cs2AgBiBr6 by Halide Defect Engineering: A DFT Study

Pb-free double halide perovskites have drawn immense attention in the potential photocatalytic application, due to the regulatable bandgap energy and nontoxicity. Herein, we first present a study for CO2 conversion on Pb-free halide perovskite Cs2AgBiBr6 under state-of-the-art first-principles calculation with dispersion correction. Compared with the previous CsPbBr3, the cell parameter of Cs2AgBiBr6 underwent only a small decrease of 3.69%. By investigating the adsorption of CO, CO2, NO, NO2, and catalytic reduction of CO2, we found Cs2AgBiBr6 exhibits modest adsorption ability and unsatisfied potential determining step energy of 2.68 eV in catalysis. We adopted defect engineering (Cl doping, I doping and Br-vacancy) to regulate the adsorption and CO2 reduction behavior. It is found that CO2 molecule can be chemically and preferably adsorbed on Br-vacancy doped Cs2AgBiBr6 with a negative adsorption energy of -1.16 eV. Studying the CO2 reduction paths on pure and defect modified Cs2AgBiBr6, Br-vacancy is proved to play a critical role in decreasing the potential determining step energy to 1.25 eV. Finally, we probe into the electronic properties and demonstrate Br-vacancy will not obviously promote the process of catalysis deactivation, as there is no formation of deep-level electronic states acting as carrier recombination center. Our findings reveal the process of gas adsorption and CO2 reduction on novel Pb-free Cs2AgBiBr6, and propose a potential strategy to improve the efficiency of catalytic CO2 conversion towards practical implementation.

Identification of urban regions' functions in Chengdu, China, based on vehicle trajectory data

Data about human trajectories has been widely used to study urban regions that are attractive to researchers and are considered to be hotspots. It is difficult, however, to quantify the function of urban regions based on the varieties of human behavior. In this research, we developed a clustering method to help discover the specific functions that exist within urban regions. This method applies the Gaussian Mixture Model (GMM) to classify regions' inflow and trip count characteristics. It regroups these urban regions using the Pearson Correlation Coefficient (PCC) clustering method based on those typical characteristics. Using a large amount of vehicle trajectory data (approximately 1,500,000 data points) in the Chinese city of Chengdu, we demonstrate that the method can discriminate between urban functional regions, by comparing the proportion of surface objects within each region. This research shows that vehicle trajectory data in different functional urban regions possesses different time-series curves, while similar types of functional regions can be identified by these curves. Compared with remote sensing images and other statistical methods which can provide only static results, our research can provide a timely and effective approach to determine an urban region's functions.

ImmunoPET imaging of CD38 in murine lymphoma models using 89Zr-labeled daratumumab

PURPOSE

CD38 is considered a potential biomarker for multiple myeloma (MM) and has shown a strong link with chronic lymphocytic leukemia due to high and uniform expression on plasma cells. In vivo evaluation of CD38 expression may provide useful information about lesion detection and prognosis of treatment in MM. In this study, immunoPET imaging with ⁸⁹Zr-labeled daratumumab was used for differentiation of CD38 expression in murine lymphoma models to provide a potential non-invasive method for monitoring CD38 in the clinic.

METHODS

Daratumumab was radiolabeled with ⁸⁹Zr (t_1/2 = 78.4 h) via conjugation with desferrioxamine (Df). After Western blot (WB) was used to screen CD38 expression in five lymphoma cell lines, flow cytometry and cellular binding assays were performed to test the binding ability of labeled or conjugated daratumumab with CD38 in vitro. PET imaging and biodistribution studies were performed to evaluate CD38 expression after injection of ⁸⁹Zr-Df-daratumumab. ⁸⁹Zr-Df-IgG was also evaluated as a non-specific control group in the Ramos model. Finally, CD38 expression in tumor tissues was verified by histological analysis.

RESULTS

Using WB screening, the Ramos cell line was found to express the highest level of CD38 while the HBL-1 cell line had the lowest expression. Df-conjugated and ⁸⁹Zr-labeled daratumumab displayed similar high binding affinities with Ramos cells. PET imaging of ⁸⁹Zr-Df-daratumumab showed a high tumor uptake of up to 26.6 ± 8.0 %ID/g for Ramos at 120 h post-injection, and only up to 6.6 ± 2.9 %ID/g for HBL-1 (n = 4). Additionally, ⁸⁹Zr-Df-IgG demonstrated a low tumor uptake in the Ramos model (only 4.3 ± 0.8 %ID/g at 120 h post-injection). Ex vivo biodistribution studies showed similar trends with imaging results. Immunofluorescence staining of tumor tissues verified higher CD38 expression of Ramos than that of HBL-1.

CONCLUSIONS

The role of ⁸⁹Zr-Df-daratumumab was investigated for evaluating CD38 expression in lymphoma models non-invasively and was found to be to a promising imaging agent of CD38-positive hematological diseases such as MM in future clinical applications.