Laboratoire de Chimie Physique

Sprouting angiogenesis is critical for embryogenesis, wound healing, and tumor growth. Here we show that the liquid crystal framework, which has recently been leveraged to study various morphogenetic events, provides unique insight into angiogenic sprouting. In response to vascular endothelial growth factor, a potent pro-angiogenic factor, endothelial cells cultured on the surfaces of soft collagen hydrogels form elongated cell streams that coexist with more polygonal cell regions. Angiogenic sprouting initiates preferentially at cell stream tips, where nematic order gradients are most pronounced. We demonstrate that cell streams are associated with large traction forces that lead to 3D deformations of the underlying hydrogel and that stream formation results from a delicate balance between microtubule polymerization and actomyosin contractility. Finally, we show that active control of nematic order allows modulation of sprout formation, highlighting the key role of EC orientation gradients in angiogenic sprouting and paving the way for new therapeutic avenues.

Titanium (Ti) is widely used in biomedical implants due to its high strength, corrosion resistance, and excellent biocompatibility. However, surface functionalization is essential to enhancing its interaction with biological environments. In this study, monolayers of citrate-stabilized, negatively charged gold nanoparticles (TCAuNPs(−)) were fabricated on Ti substrates precoated with poly(allylamine hydrochloride) (PAH) to facilitate electrostatically driven adsorption. The adsorption behavior of two amino acids, cysteine (Cys) and tryptophan (Trp) on TCAuNPs(−) deposited on the modified Ti surface, was investigated using atomic force microscopy combined with surface-enhanced infrared absorption (AFM-SEIRA) spectroscopy, enabling nanoscale chemical analysis of biomolecular interactions on the modified surface. The AFM-SEIRA spectra revealed characteristic bands associated with COO– and NH3+ groups for both amino acids. In addition, Trp exhibited prominent signals from the aromatic indole ring, suggesting that these molecular fragments were adsorbed onto the TCAuNPs(−)/Ti surface. AFM-SEIRA results indicate that the strongest amino acid signals were localized at the nanoparticle apexes. The results provide insight into the early stage molecular interactions at the bionano interface and offer a framework for designing new functionalized implant surfaces.

The Front Cover evokes particle swarm optimization applied to Bi–Pt bimetallic nanoparticles. Each bird represents a candidate nanoparticle structure. The lake and its shorelines represent the potential energy surface, generated using the ChiMES physics-informed machine learning potential. The surrounding mountains symbolize transition states, while the dark whirlpool at the lake’s center is the global energy minimum. More information can be found in the Research Article by N. T. Van-Oanh and co-workers (DOI: 10.1002/cphc.202500268).

In the structure of the title compound, 4C22H28N2O3·C2H6O, mol-ecules composed of an acyl-hydrazone segment bridging a 3,5-di-tert-butyl-phenol unit and a 2-hy-droxy-phenol unit form columnar quartet channels along the a-axis, within which disordered ethanol solvent mol-ecules reside in two inversion-centre-related positions. Inter-molecular hydrogen bonds assemble the channels between the columnar mol-ecules through the hosted ethanol mol-ecule, complemented by weaker van der Waals-type inter-actions. These weak van der Waals inter-actions also hold the columns together. Additionally, the title compound demonstrated notable thermal stability at temperatures of up to 251°C. The sharp melting point peak observed in the DSC confirmed its crystalline structure.

Titanium dioxide (TiO2), a widely used semiconductor in photocatalysis owing to its adequate potential for water hydrolysis, chemical stability, low toxicity, and low cost. However, its efficiency is limited by fast charge-carrier recombination and poor visible light absorption. Coupling TiO2 with a p-type semiconductor, such as nickel oxide (NiO), forming a p-n heterojunction, decreases the recombination of charge carriers and increases photocatalytic activity. In this work, the surface of TiO2 modified with NiO nanoparticles (NPs) induced by radiolysis for photocatalytic hydrogen production was studied. The photocatalytic activity of NiO/TiO2 was evaluated using methanol as a hole scavenger under UV–visible light. All modified samples presented superior photocatalytic activity compared to bare TiO2. The dynamics of the charge carriers, a key electronic phenomenon in photocatalysis, was investigated by time-resolved microwave conductivity (TRMC). The results highlight the crucial role of Ni-based NPs modification in enhancing the separation of the charge carrier and activity under UV–visible irradiation. Furthermore, the results revealed that under visible irradiation, NiO-NPs inject electrons into the conduction band of titanium dioxide.

Complexation of U(IV) by encapsulation into the cavity of a 1,4,7‐triazacyclonane (tacn) macrocycle functionalized by phosphonated pyridyl arms affords a water‐stable and soluble [U(IV)L] complex. The coordination process was monitored by electronic UV‐Vis‐NIR absorption spectroscopy and the corresponding complex was characterized by 1H‐, 13C‐ and 31P‐NMR spectroscopy and by mass spectrometry. Density functional theory (DFT) modeling shows the cation to be embedded into the cavity of the nonadentate ligand, as confirmed by analysis of the paramagnetic contributions of U(IV) on the chemical shifts of the proton nuclei. This effective chelation enabled the observation of a broad NIR emission band centered at 1080 nm observed for the first time in addition to UV‐visible emission arising from the U(IV) cation upon electronic excitation in the UV‐blue region. The [U(IV)L] complex was shown to be hydrolytically stable for several weeks in aqueous solutions over a broad range of pH values (from 1.6 to 10) under aerobic conditions.

Abstract The development of active and durable photocatalysts without noble metals for green hydrogen generation is a major challenge in photocatalysis. Herein, composite nanomaterials based on TiO2 coupled with HKUST‐1, a copper metal–organic framework, for hydrogen generation by photocatalysis using water and methanol as sacrificial agents are developed. To design a highly active composite, the mass ratios between HKUST‐1 and TiO2 are studied and optimized. The photoactive composite materials are characterized by TEM, UV–vis spectroscopy, FTIR, XRD, XPS, and photoelectrochemical studies. The charge carrier dynamics is also studied by time‐resolved microwave conductivity and the crucial role of the copper is also investigated by XPS and electron paramagnetic resonance. DFT calculations are also used to understand the mechanism involved in H2 generation. The findings reveal a high hydrogen evolution rate of HKUST‐1/TiO2 (5.11 mmol g−1 h−1) for the first cycle with the mass ratio (1:20). This activity increases with cycling until surpassing the performance of the 1 wt.% Pt (TiO2) material, used as a benchmark and known as a reference in terms of photocatalytic hydrogen production, and a rate of 13.24 mmol g−1 h−1 is obtained after the sixth cycle.