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Abstract Many micro-particles including pathogens strongly adhere to hosts. It remains elusive how macrophages detach these surface-bound particles during phagocytosis. We show that, rather than binding directly to these particles, macrophages form unique β2 integrin-mediated adhesion structures at the cell-substrate interfaces, specifically encircling the surface-bound particles. These circular adhesion structures that we named phagocytic adhesion rings (PARs) serve as strongholds to support local ring-shaped actin structures constricting into the particle-substrate cleavages, thereby pinching off the particles from the substrate. During this process, integrins in PARs sustain tensions due to the reaction force of actin polymerization against the particles. Such tensions are critical for phagocytic efficiency of surface-bound particles. PARs were formed in all tested macrophages (mouse, human and fish) and micron-sized particles (microbeads and E. coli), demonstrating their conserved role in the phagocytosis. This study reveals a mechanism of PAR-mediated phagocytosis, specialized for the detachment and internalization of surface-bound particles.

Many micro-particles including pathogens strongly adhere to hosts. It remains elusive how macrophages detach these surface-bound particles during phagocytosis. We show that, rather than binding directly to these particles, macrophages form unique β2 integrin-mediated adhesion structures at the cell-substrate interfaces, specifically encircling the surface-bound particles. These circular adhesion structures that we named phagocytic adhesion rings (PARs) serve as strongholds to support local ring-shaped actin structures constricting into the particle-substrate cleavages, thereby pinching off the particles from the substrate. During this process, integrins in PARs sustain tensions due to the reaction force of actin polymerization against the particles. Such tensions are critical for phagocytic efficiency of surface-bound particles. PARs were formed in all tested macrophages (mouse, human and fish) and micron-sized particles (microbeads and E. coli), demonstrating their conserved role in the phagocytosis. This study reveals a mechanism of PAR-mediated phagocytosis, specialized for the detachment and internalization of surface-bound particles. It remains elusive how macrophages internalize surface-bound particles. Here, authors discover an adhesion complex at the cell-substrate interface, which coordinates with F-actin to dislodge particles from the surface. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal CrystEngComm, which focuses on solid-state and crystalline materials. It includes information about the articles and papers in the issue, as well as details about the journal's editorial board. The journal welcomes studies on various aspects of crystal behavior and engineering. The article in this issue explores the electrocatalytic hydrogen production activity of a copper(II)-dipyridylamine complex in acidic water. The authors conducted experiments to investigate the efficiency of this complex in generating hydrogen gas, providing valuable insights into its potential as a catalyst for hydrogen production. [Extracted from the article]

A water-stable and structurally-characterized earth-abundant copper(II) complex, [Cu(dpa)2(N3)]Cl·4H2O, containing an N,N-chelator (dpa = 2,2′-dipyridylamine) and an ancillary ligand (N3− = azide ion) was synthesized and evaluated for electrocatalytic H2 production activity in water using acetic acid as a proton source. Crystal engineering approach revealed the presence of multiple lattice water molecules and a chloride ion in the secondary coordination zone of the distorted square pyramidal copper(II) complex forming an 8-membered tetrameric water cluster and, subsequently, an 11-membered hexameric water cluster in a repetitive mode in association with a water-chloride cluster, leading to a beautiful long-range supramolecular framework involving the chains of a copper(II) complex. The copper catalyst exhibited excellent hydrogen generation activity for the electrochemical proton reduction in acidic water with a rate of 49.81 s−1. A Faradic efficiency of 71% was derived from controlled potential electrolysis (CPE) with [Cu(dpa)2(N3)]+ at −1.25 V vs. Ag/AgCl for 3 h using a glassy carbon electrode ensuring a high turnover number of 41.96 and the desired durability of the molecular electrocatalyst under electrochemical conditions. Further, electrochemical, spectroscopic, and computational studies propose the proton-coupled reduction mechanism for the hydrogen evolution where endo conformational Hδ+⋯Hδ− coupling effectively releases molecular hydrogen. [ABSTRACT FROM AUTHOR]

The properties and functions of non-covalent interaction-driven fluorescent supramolecular self-assembly depend greatly on their evolution dynamics. Electron microscopy, atomic force microscopy, and confocal laser scanning microscopy have been used to elucidate the formation of molecular self-assembly. However, some pertinent issues, such as the drying or freezing of the sample for electron microscopy, the influence of the interactions between the tip and the sample in atomic force microscopy imaging, and the low spatial resolution of confocal laser scanning microscopy images, often impede the real-time analysis and exploration of the dynamics of molecular self-assembly processes. In this context, fluorescence correlation spectroscopy and fluorescence lifetime imaging microscopy have recently been explored to unravel the physical picture of the in situ growth dynamics and stimuli-induced morphological transformation of luminescent self-assembled structures. The current highlight article demonstrates the need for fluorescence correlation spectroscopy and fluorescence lifetime imaging microscopy to acquire precise information on the dynamics and morphological evolution of fluorescent self-assembled architectures using a few remarkable recent studies. In addition to the current status and challenges, the future directions for the further exploration of dynamic self-assembly processes towards developing next-generation functional materials have been delineated. [ABSTRACT FROM AUTHOR]

We report the photophysical properties, self‐assembly and biological evaluation of an isothiazolanthrone‐based dye, 7‐amino‐6H‐anthra[9,1‐cd]isothiazol‐6‐one (AAT), which reveals anticancer properties and can be potentially used as dye for monitoring cell viability. The solvent‐dependent photophysical studies suggest that the emission of AAT is sensitive to environment polarity due to which interesting changes in the colored emission may be observed owing to the charge transfer (CT) processes. AAT also self‐assembles to tree‐like branched morphologies and produce, a greenish emission inside the cells when imaged after short interval (15 mins) of incubation while a red fluorescence could be noted after 24 h. Interestingly, AAT also produce differential emission inside mouse normal cells as compared to its cancer cell lines since it possess anticancer activity. The experimental observations were also validated theoretically via computational modeling. [ABSTRACT FROM AUTHOR]

This study highlights the design, synthesis, spectroscopic characterization and catalytic phosphoesterase cleavage activity of two isostructural and isomorphous complexes, [Cu(L)]4 (1) and [Ni(L)]2·CH3OH (2) containing a new synthetic N,N-type donor ligand, namely 1,3-bis(((E)-(1H-pyrrol-2-yl)methylene)amino)propan-2-ol (H2L). The ligand, H2L has been synthesized by coupling of pyrrole-2-carboxaldehyde and 1,3-diamino-propane-2-ol under reflux. X-Ray crystallography study reveals that both the Cu(II) and Ni(II) centres in 1 and 2 adopt nearly a perfect square planar geometry and they display a high degree of similarity in their structural features. The biocatalytic fate of the complexes has been evaluated towards the hydrolytic cleavage of the phosphoester linkage in an aqueous DMF medium at room temperature. The spectrophotometric studies favour a higher turnover frequency for the hydrolysis of phosphoester bonds for the copper(II) complex (kcat, 1.56 × 104 h−1) over the nickel(II) complex (kcat, 5.61 × 103 h−1). Electrochemical, spectrophotometry, electron spray ionization mass spectrometry and detailed density functional theory studies illuminate the mechanistic interpretation attributing the crucial role of coordinated water, facilitating the nucleophilic attack on the phosphorous centre of pNPP, and shed light on mechanistic aspects for the efficient hydrolysis of phosphoester substrates for the copper complex over the nickel complex. [ABSTRACT FROM AUTHOR]

A photo‐switchable ionophore, (E)‐4‐([2‐hydroxy‐3‐methoxybenzylidene]amino)‐1,5‐dimethyl‐2‐phenyl‐1,2‐dihydro‐3H‐pyrazol‐3‐one (S1), was rationally designed and developed for the visible light‐triggered selective and efficient transport of Al (III) ions. The non‐fluorescent probe distinctly manifests its green light at 518 nm in presence of Al (III) ion upon irradiation at 405 nm and showed a turned‐off emission with EDTA in ethanol. The binding mode and structural perspective of S1 were assessed through X‐ray crystallography, spectrophotometry, spectrofluorimetry, 1H nuclear magnetic resonance (NMR) titration, electrospray ionization mass spectrometry (ESI‐MS) analysis and computational calculations, suggesting a 1:1 binding stoichiometry and a distorted tetrahedral coordination geometry of S1‐Al complex. The testing strip was also developed with S1 coating for colourimetric and naked‐eye detection of Al (III) ion as evident from the green fluorescence upon irradiation at 365 nm. Further, a bioimaging study of S1 in human colon living cells (HP‐29) revealed the presence of Al (III) ion through a bright green fluorescence in HP‐29, indicating the potentiality of S1 to trace Al (III) in living cells. Additionally, cytotoxicity studies by MTT assay and staining analysis ensured that the probe might be an efficient and sensitive chemosensor for monitoring Al (III) ion in drug delivery and biological applications. [ABSTRACT FROM AUTHOR]

Porous organic polymers (POPs) have received increasing attention due to their properties, such as permanent porosity with tunable pore size, robust structure, high surface area, and versatility of the backbone for the desired function. Such properties prove to be quite valuable for a plethora of sustainable applications. POPs can largely be classified as crystalline or amorphous based on the degree of long-range order. Crystalline POPs such as two-dimensional covalent organic frameworks possess characteristics such as unimodal pores with long one-dimensional pore channels allowing size-selective guest recognition, whereas amorphous network POPs give rise to a hierarchical pore size distribution enabling facile ion and mass transport. Since structure plays an undeniably vital role in the function, POPs with contrasting degrees of long-range order are suitable for some applications more than others. To address this conundrum, here we discuss at length the impact of the extent of structural order of the POPs in the context of four key applications, namely water treatment, electrochemical energy storage, heterogeneous catalysis, and optical sensing along with light-harvesting. Additionally, the formation principles of POPs with varying degrees of long-range order in view of kinetics and thermodynamics have been outlined. Furthermore, we provide a general guideline for the specific use of crystalline and amorphous POPs along with future avenues of exploration mitigating the current challenges towards the design of task-specific new-generation functional porous materials. [ABSTRACT FROM AUTHOR]

The development of luminescent probes has gained significant interest in real-time intracellular sensing and imaging of various biologically relevant species. The accuracy in sensing and imaging circumventing the background signals due to autofluorescence is essential to decipher subtle changes in cellular microenvironments under diverse pathophysiological conditions. In this context, luminescent probes for background-free imaging demands rational molecular design strategies along with various optical features like lower energy and multiphoton excitation, larger Stokes or anti-Stokes shift, and long-lived emission. Multiphoton microscopy employing two-photon absorbing molecular materials and upconversion nanoprobes is beneficial for deep-tissue imaging. In contrast, organic long-lived emissive probes, including thermally activated delayed fluorescence and room temperature phosphorescence materials, provide promising scope for time-gated imaging, ruling out the dependency on probe concentration and laser power. On the other hand, bioluminescent and chemiluminescent molecular probes producing excited-state emissive species without any optical excitation are emerging candidates for autofluorescence-free intracellular sensing and imaging. In this review article, we delineate versatile design strategies, including the choice of luminescent cores, targeting units, and sensing sites, for the development of multifunctional probes with improved intracellular sensing and imaging. Moreover, a brief discussion of different photophysical pathways involved in signalling processes is provided. The current challenges in targeted intracellular delivery of the probes for non-invasive sensing and imaging are indicated. Finally, we emphasize the future prospects of multiphoton excitable or self-illuminating long-lived emissive probes with state-of-the-art super-resolution microscopy techniques for intracellular sensing and imaging with nanoscale resolution. [ABSTRACT FROM AUTHOR]