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π-Extended Ru–COUBPY Photosensitizers for In Vivo Anticancer Phototherapy Using One-Photon 780 nm Near-Infrared Light
No full textInternational audiencePhotodynamic therapy (PDT) is a promising cancer treatment modality, offering precise spatial and temporal control of drug activation using light. However, clinical translation of current photosensitizers (PSs) is limited by inefficient activation at wavelengths within the phototherapeutic window, especially in the deep-red and near-infrared (NIR) region. NIR light provides advantages such as reduced absorption by endogenous chromophores, minimized tissue photodamage, and improved tissue penetration, highlighting the need for PSs to be activatable in this range. Herein, we report a novel series of ruthenium(II) polypyridyl complexes (Ru4-7) featuring πextended COUBPY ligands, designed via a vinylogation strategy and synthesized through an innovative postcoordination ligand assembly approach. This structural modification enhances molar absorptivity and red-shifts the absorption bands well into the NIR region without substantially compromising photostability. Complexes Ru4-7 efficiently generate both Type I and Type II reactive oxygen species, and their photodynamic activity, combined with preferential mitochondrial accumulation, leads to potent nanomolar phototoxicity against CT-26 colorectal cancer cells under deep-red and NIR irradiation, even under hypoxia. Notably, the lead complex Ru6 demonstrated strong in vivo phototoxicity in mice bearing subcutaneous CT-26 tumors, achieving significant tumor growth inhibition upon irradiation with 660 and 780 nm light. Ru6 thus represents one of the first Ru(II) polypyridyl complexes to exhibit robust in vivo PDT antitumor activity under one-photon NIR activation. Its broad wavelength activation profile further underscores its potential versatility for treating tumors of varying size and anatomical location depending on specific light penetration requirements. These findings mark a promising step toward nextgeneration PSs for treating deep-seated and hypoxic tumors
Identification, quantification and sourcing of fossil hydrocarbons in ancient Egyptian mummies by V and Ni trace elements
No full textInternational audienceEgyptian mummies are often covered with black embalming matter, which is made of complex mixtures of natural organic substances such as vegetable resins, beeswax, animal fats, gums, and vegetable oils, as well as bitumen. In this work, we used proton-induced X-ray emission (PIXE) and electron paramagnetic resonance (EPR) to investigate the potential of certain transition metals, in particular V and Ni, as probes for detecting the presence of bitumen and tracing its origin and alteration in this black embalming matter. PIXE analysis showed that all the mummies studied in this work (bird, ram, crocodile, human), which span a period of about 1000 years and come from different sites in Egypt, have a nearly constant Ni/V ratio close to that of bitumen from the Dead Sea, suggesting a well-defined source of bitumen supply. The same conclusion was reached by EPR analysis of vanadyl porphyrins and carbonaceous radicals. The presence of an excess of radicals in the black matter from several mummies indicates that they probably contain some carbonized organic matter in addition to bitumen. This combined PIXE-EPR methodology is quantitative and sensitive since a few % of bitumen can be non-destructively detected in a mummy sample weighing only a few mg. The combination of these two techniques can provide new information on the thermal history (preparation recipes) and redox history (natural degradation) of this black matter
Amorphous GaN matrix embedded nanocrystals exhibiting bulk band-gap luminescence
No full textInternational audienceThis work reports on room temperature sputtering growth of GaN thin films, exhibiting band-edge luminescence without thermal annealing or post-deposition processing. Particularly, we investigate and correlate their luminescence spectra with their structural properties (amorphous or polycrystalline phases), the presence of defects, and the grain features by combining cathodoluminescence and HR-TEM characterizations. The working pressure and Ar/N2 flow ratio are found to have a profound effect on both the structural and optical properties of the films. Notably, the only film with band-edge luminescence is grown at the highest investigated pressure (13.3 Pa) and 40%N2 concentration and exhibits single-grained crystallites of small sizes (~5nm). Moreover, this polycrystalline film has an almost equal fraction of amorphous and crystalline phases. This suggests that the presence of smooth and nanometer-sized crystals in an amorphous matrix (inducing grain surface passivation) could be a synergetic combination to achieve luminescent films grown at room temperature.</div
Low-Temperature, PECVD-Grown Nanocrystalline Silicon Oxide as a Metal Diffusion Barrier for Silicon Heterojunction Solar Cells
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Two new Iron(III) bis(DMAP) Meso-arylporphyrin complexes: UV/Vis, IR, 1H NMR, EPR, and electrochemical characterization investigations, electrochemical detection of Pb2+
No full textInternational audienceThe synthesis and characterization of two new bis(4-dimethylaminopyridine) (DMAP) meso-arylporphyrin ion complexes are reported. It's about the [Fe III (TpivPP)(DMAP) 2 ] + (1) (TpivPP = α,α,α,α-tetrakis(o-pivalamidophenyl)porphyrinate) and [Fe III (T3,5-OMePP)(DMAP) 2 ] + (2) (T3,5-OMePP = 3,5-dimethoxyphenyl) porphyrinato) ion complexes. Both complexes 1-2 have been studied with ESI mass spectrometry and UV/Vis, IR, 1 H NMR and RPE spectroscopic techniques. The EPR spectra of these two bis(DMAP) ferric metalloporphyrins present normal rhombic spectra. The single crystal molecular structures of complexes 1-2 show that the porphyrin macrocycles of these ferric species present high ruffling deformation and that the planes of the two trans DMAP axial ligands adopt perpendicular orientation. These spectroscopic and structural results indicate that both two [Fe III (Porph)(DMAP) 2 ] + (Porph = TpivPP or T3,5-OMePP) exhibit the common ( d xy ) 2 ( d xz , d yz ) 3 electronic configuration.In this study, two electrochemical sensors were developed using complexes 1-2. Screen-printed carbon electrodes (SPCE) were functionalized with these complexes, resulting in Complex 1/SPCE and Complex 2/SPCE systems, employed for electrochemical detection of Pb 2+ ion using differential pulse voltammetry (DPV). Electrochemical properties were investigated by means of EIS (Electrochemical impedance spectroscopy) and CV (Cyclic Voltammetry) studies
Chemical inhibition of light-induced decomposition by hindered amine for efficient and stable perovskite solar cells
No full textInternational audienceDespite significant advancements in improving the power-conversion efficiency (PCE) of exceeding 27% in perovskite solar cells (PSCs), the insufficient operational stability of PSCs under illumination remains a critical challenge, posing a major obstacle to their commercial viability. This paper proposes a feasible hindered amine stabilization strategy (HASS) by using a hindered amine light stabilizer for grain and surface modulation of perovskite, thereby blocking the internal and external degradation pathways of perovskite. Its piperidine ring is easily oxidized to form Nitrogen monoxide (N–O•) radicals after absorbing light energy in an aerobic environment. The free superoxide radical (O2•−) radicals react with perovskite and H+ in the decomposition products of perovskite, thereby improving the light stability of the device. In addition, the contained triazine and morpholine functional groups can coordinate with Pb2+, thereby reducing the interface defects and inhibiting the non-radiative recombination. The HASS-modulated PSC could reach the champion PCE of 26.74% (certified 26.56%), which is remarkable for inverted PSCs prepared under ambient conditions. Further, the unencapsulated device could maintain 95.4% of its initial PCE after more than 1000 hours of aging at maximum power point tracking
BDNF exerts an NRF2-dependent cytoprotective function via a receptor-independent pathway
No full textInternational audienceThe ancestral and ubiquitous KEAP1-NRF2 cellular defense system is controlled by chemical inducers and intracellular proteins. Here, we show that an extracellular protein, BDNF, can directly control this cytoprotective system via a receptor-independent pathway. Thanks to a highly conserved C-terminal CPP sequence, BDNF freely crosses the cell membrane, binds to KEAP1, and thereby promotes the nuclear translocation of NRF2 to exert an effective cytoprotective effect. The high conservation of the CPP sequence over 450 million years demonstrates the essential role of this signaling pathway. The receptor-independent cytoprotective effect, in addition to the canonical receptor-dependent neurotrophic effect, shows that a protein can exert distinct effects via receptor-dependent and receptor-independent mechanisms, as described for small molecules. As extracellular BDNF is present throughout the body, it can control the cellular defenses of cells, including those without receptors. Consequently, any change in BDNF extracellular levels is likely to modify the cytoprotective response and thus contribute to numerous pathologies
Spacer Loss upon 2D Ruddlesden–Popper Halide Perovskite Annealing Raises Film Properties and Solar Cell Performances
No full textInternational audienceUsing reduced-dimensional halide perovskites is emerging as a promising strategy for enhancing the stability of optoelectronic devices such as solar cells, even if their performances remain a step below those of the 3D halide perovskites. Two-dimensional Ruddlesden–Popper (2D-RP) structures are characterized by the n parameter that represents the number of PbI6 layers in the spacer-separated perovskite slabs. The present study focuses on formamidinium (FA)-based 2D-RP type perovskites denoted as PMA2FAn−1PbnI3n+1 (PMA = Phenylmethylammonium or benzylammonium). We investigate the effect of n on the one step growth mechanism and the film morphology, microstructure, phase purity, and optoelectronic properties. Our findings demonstrate that the average n is not only determined by the initial spacer content in the precursor solution but also by the thermal annealing process that leads to a partial spacer loss. Depending on n, perovskite solar cells achieving a power conversion efficiency up to 21%, coupled with enhanced film stability compared to 3D perovskites have been prepared. By using MACl additive and an excess of PbI2 in the perovskite precursor solution, we have been able to achieve high efficiency and to stabilize the n = 5 perovskite solar cells. This research represents a significant stride in comprehending the formation of FA-based layered perovskites through one-step sequential deposition, enabling control over their phase distribution, composition, and orientation
Deferasirox derivatives as inhibitors of Kallikrein‐related peptidases associated to neurodegenerative diseases
No full textInternational audienceKallikrein‐related peptidases are a family of serine proteases which loss of activity regulation has been particularly linked to neurodegenerative diseases. Moreover, iron overload is also a key process in some of these leading pathological conditions, particularly Alzheimer’s disease. We identified for the first time Deferasirox, a well‐known FDA‐approved iron chelator (DFX) as an initial hit for kallikrein’s (KLK) inhibition and propose here the design and synthesis of a small library of molecules using DFX as chemical scaffold. Resulting sub‐series of compounds were evaluated against lead central nervous system KLK’s, namely KLK1, KLK6 and KLK8 using targeted pharmacomodulations on DFX. Beyond DFX, several reversible micromolar inhibitors of these KLKs have been identified as hits and were shown to be devoid of any noticeable cytotoxicity towards neural cell lines commonly used in the field of neurodegenerative diseases. Their ability to chelate iron was also assessed in comparison to DFX and preformed iron‐compound complexes displayed slightly improved inhibition potency for some derivatives with a KLK‐dependent manner. Hence, we identified several DFX derivatives as promising starting points for the development of dual therapeutic agents in the context of neurodegenerative diseases where both deregulated KLK’s proteolysis and iron dysregulation are involved
