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Density functional theory calculations (DFT), coupled with microkinetic modelling, have been used to simulate Temperature Programmed Desorption (TPD) experiments for calcined ceria nanopowders with the aim to gain insight into the chemistry governing their high redox activity. Our simulations consider two main nanoparticle models. One is a perfect ceria octahedron supercharged with adsorbed oxygen molecules turned into superoxide ions, as has previously been used to explain the enhanced oxygen storage capacity (OSC) in nanoceria. The other model is a variant where we have introduced oxygen vacancies under ridge Ce ions, thereby reducing their coordination numbers to five. The results from our microkinetic modelling suggest that including such five-coordinated Ce adsorption sites results in a TPD spectrum that better matches the experimental counterpart in terms of both peak position and width. In addition, this new structural model allows for the co-existence of Ce 3 + ions, superoxide ions and O2 molecules, as seen in experiments in the literature.

Despite the efficacy of current starvation therapies, they are often associated with some intrinsic drawbacks such as poor persistence, facile tumor metastasis and recurrence. Herein, we establish an extravascular gelation shrinkage-derived internal stress strategy for squeezing and narrowing blood vessels, occluding blood & nutrition supply, reducing vascular density, inducing hypoxia and apoptosis and eventually realizing starvation therapy of malignancies. To this end, a biocompatible composite hydrogel consisting of gold nanorods (GNRs) and thermal-sensitive hydrogel mixture was engineered, wherein GRNs can strengthen the structural property of hydrogel mixture and enable robust gelation shrinkage-induced internal stresses. Systematic experiments demonstrate that this starvation therapy can suppress the growths of PANC-1 pancreatic cancer and 4T1 breast cancer. More significantly, this starvation strategy can suppress tumor metastasis and tumor recurrence via reducing vascular density and blood supply and occluding tumor migration passages, which thus provides a promising avenue to comprehensive cancer therapy., The efficacy of tumour starvation therapy is limited by lack of persistent tumour suppression, tumour metastasis and recurrence. Here, the authors report biocompatible gold nanorods and thermal-sensitive hydrogel to promote narrowing of blood vessels and show this to reduce tumour growth and metastasis.

The first layer of atoms on an oxide catalyst provides the first sites for adsorption of reactants and the last sites before products or oxygen are desorbed. We employ a unique combination of morphological, structural, and chemical analyses of a model ceria catalyst with different surface terminations under an H2 environment to unequivocally establish the effect of the last layer of atoms on surface reduction. (111) and (100) terminated epitaxial islands of ceria are simultaneously studied in situ allowing for a direct investigation of the structure–reducibility relationship under identical conditions. Kinetic rate constants of Ce4+ to Ce3+ transformation and equilibrium concentrations are extracted for both surface terminations. Unlike the kinetic rate constants, which are practically the same for both types of islands, more pronounced oxygen release, and overall higher reducibility were observed for (100) islands compared to (111) ones. The findings are in agreement with coordination-limited oxygen vacancy formation energies calculated by density functional theory. The results point out the important aspect of surface terminations in redox processes, with particular impact on the catalytic reactions of a variety of catalysts.

Cloud platforms allow users to execute tasks directly from their web browser and are a key enabling technology not only for commerce but also for computational science. Research software is often developed by scientists with limited experience in (and time for) user interface design, which can make research software difficult to install and use for novices. When combined with the increasing complexity of scientific workflows (involving many steps and software packages), setting up a computational research environment becomes a major entry barrier. AiiDAlab is a web platform that enables computational scientists to package scientific workflows and computational environments and share them with their collaborators and peers. By leveraging the AiiDA workflow manager and its plugin ecosystem, developers get access to a growing range of simulation codes through a python API, coupled with automatic provenance tracking of simulations for full reproducibility. Computational workflows can be bundled together with user-friendly graphical interfaces and made available through the AiiDAlab app store. Being fully compatible with open-science principles, AiiDAlab provides a complete infrastructure for automated workflows and provenance tracking, where incorporating new capabilities becomes intuitive, requiring only Python knowledge., Comment: Manuscript: 25 pages, 6 figures. Supplementary information: 15 pages, 10 figures

Prequenching and selective activation of photosensitizer (PS) are highly desired in photodynamic therapy (PDT) to avoid off-target effect due to nonspecific activation and poor targeting selectivity of PS. In this study, nanographene materials as a unique π-conjugated planar system for electronic transfer were employed as the robust platform for temporarily quenching of PS. Photosensitizer chlorin e6 (Ce6) was integrated onto planar structure of graphene quantum dot (GQD) or graphene oxide (GO) via a reduction cleavable disulfide linker. The formed hybrid nanosystem displayed considerable fluorescence quenching and slight phototoxicity, even under the condition of light irradiation, while the photoactivity of PS could be selectively recovered in the presence of the reducing agent. Compared with graphene oxide system with larger size (around 200 nm), GQD nanosystem exhibited significantly improved tumor accumulation via enhanced permeation and retention effect (EPR effect). The in vivo study demonstrated extremely effective suppression of tumor growth for the group treated with the GQD nanosystem with cleavable linker, revealing the promising application of the presented novel strategy.

In photodynamic therapy (PDT), selective activation of the photosensitiser in tumor-relevant conditions is highly desirable to avoid side effects. In this study, a graphene quantum dot (GQD) nanosystem, composed of a redox-triggered cleavable PEG shell, was designed and developed for selective recovery of photoactive chlorine e6 (Ce6) in tumor-relevant conditions. In this unique system, the planar π conjugated structure of GQD enables efficient quenching of the photochemical properties of Ce6 in terms of fluorescence and singlet oxygen generation. Once exposed to tumor relevant glutathione (GSH), the disulfide-linked PEG shell undergoes reductive cleavage and subsequent detachment from the GQD scaffold, leading to accelerated release of Ce6 with recovered photoactivity. MTT study against HeLa cells demonstrated the high PDT efficacy of Ce6, regulated by elevated GSH concentration. The studies on in vivo/ex vivo imaging and photodynamic efficacy demonstrated superior biocompatibility of the GQD nanosystem compared with the widely reported graphene oxide (GO)-based nanovehicle. Intravenously injected GQD–SS–PEG/Ce6 showed effective suppression of tumor growth.

Magnetically induced current densities and integrated ring-current strength susceptibilities have been calculated at the density functional theory (DFT) level for a test set consisting of 17 ring-shaped molecules using the gauge-including magnetically induced current (GIMIC) method. Reliable values for the ring-current strengths have been obtained by performing numerical integration of the current-density susceptibility passing a cut plane perpendicularly to the molecular ring. The current densities and ring current strengths were calculated at the DFT level using the B3LYP functional and def2-TZVP basis sets. Current densities and ring-current strengths have also been calculated at the Hartree-Fock self-consistent field (HF-SCF) level using Dunning’s aug-cc-pVTZ basis sets, which allow a direct comparison with ring-current strengths that have previously been estimated using ring-current models based on magnetic shielding calculations. Current density calculations at both levels of theory show that the magnetic shielding based ring-current models are not a very accurate means to estimate the magnetically induced ring current strengths, whereas they provide qualitatively the correct aromaticity trends for the studied molecules.

Several studies have reported a dramatically increased oxygen storage capacity (OSC) for small ceria nanoparticles (∼5 nm). Both experiments and theory have correlated this effect with superoxide ion formation. In previous studies, density functional theory (DFT) calculations with the PBE+U density functional have been used, and the obtained results were only in qualitative agreement with the experimental observations. One severe problem is the underbinding of the O2 molecule upon superoxide ion formation, which suggests that such species should not exist above room temperature. In this work, we use hybrid DFT functional to resolve this problem. We find that the discrepancy between theory and experiment originates from an incorrect estimate of the energy associated with the localized f-electrons with respect to the oxygen p-levels. By using average O2 adsorption energies from hybrid DFT calculations, extrapolated to large nanoparticles (3−10 nm), in conjunction with first-order desorption kinetics, we fin...