In the search for biocompatible composite microspheres to be used as a hemostatic agent, in a previous study, we designed a novel biomaterial, consisting of composite microspheres containing three natural biological ingredients, carboxymethyl chitosan, sodium alginate and collagen (CSCM). Furthermore, the chemical and physical properties, hemostatic ability, biocompatibility and cytotoxicity were investigated in vitro. In this work, the in vivo hemostatic performance, wound healing, hemocompatibility, histocompatibility, and biodegradability were evaluated by a series of experiments. The results showed that CSCM could both stop bleeding and enhance healing efficiency by accelerating the clotting and the wound closure rate, suggesting that CSCM acts as a hemostat, and enhances wound healing. In addition, the CSCM material had negligible intracutaneous stimulation reactions and no obvious hemolytic reactions. More importantly, CSCM can be degraded in vivo without significant impacts on physiology, biochemistry, and organization. Thus, CSCM may be a useful tool to stop bleeding in emergency conditions in both military and civilian settings.

One-pot reaction of tris(2-aminoethyl)amine (TREN), [CuI(MeCN)4]PF6, and paraformaldehyde affords a mixed-valent [TREN4CuIICuICuI(μ3-OH)](PF6)3 complex. The macrocyclic azacryptand TREN4 contains four TREN motifs, three of which provide a bowl-shape binding pocket for...

Endoplasmic reticulum (ER) is sensitive to changes in the intracellular environment such as pH and viscosity, and slight changes may trigger stress response. Besides, different from apoptosis and necrosis, ferroptosis is the result of lipid peroxidation accumulation. There is evidence that ferroptosis is closely related to endoplasmic reticulum stress (ERS). However, the possible changes in the pH and viscosity of the ER during the ferroptosis process have not yet been studied. Therefore, we used a new type of ER-targeted dual-excitation fluorescent probe (DSPI-3) to investigate the possible changes of pH and viscosity of ER during the ferroptosis. The novel probe DSPI-3 exhibited a highly sensitive and selective response to pH and viscosity. During the bioimaging process, it was found that the ER acidified and viscosity increased during the ferroptosis process induced by erastin, while the cells treated with ferrostatin-1 did not alter significantly. In addition, when dithiothreitol (DTT) and erastin stimulated the cells at the same time, we discovered that ER was acidified considerably at short notice, but the pH was slightly increased in the later stage. Besides, the change of the viscosity enhanced slowly with the passage of time, and there was a noteworthy decline in the later stage, demonstrating that the DTT-induced ERS accelerated the process of ferroptosis. We hope that this unique fluorescent probe can provide an effective method for studying the relationship between ERS and ferroptosis.

Metal clusters in enzymes carry out the life-sustaining reactions by accumulating multiple redox equivalents in a narrow potential range. This redox potential leveling effect commonly observed in Nature has yet to be reproduced with synthetic metal clusters. Herein, we employ a fully encapsulated synthetic tricopper complex to model the three-electron twoproton reductive regeneration of fully reduced trinuclear copper clusterin multicopper oxidases (MCOs). The tricopper cluster can access four oxidation states (I,I,I to II,II,II) and four protonation states ([Cu 3 (μ 3 -O)] LH, [Cu 3 (μ 3 -OH)]L, [Cu 3 (μ 3 -OH)]LH, and [Cu 3 (μ 3 -OH 2 )]L, where LH denotes the protonated ligand), allowing mechanistic investigation of proton-coupled electron transfer (PCET) relevant to MCOs. Seven tricopper complexes with discrete oxidation and protonation states were characterized with spectroscopy or X-ray single-crystal diffraction. A stepwise electron transfer−proton transfer (ET−PT) mechanism is established for the reduction of Cu II Cu II Cu II (μ 3 -O)LH to Cu II Cu II Cu I (μ 3 -OH)L, while a stepwise PT−ET mechanism is determined for the reduction of Cu II Cu I Cu I (μ 3 -OH)LH to Cu I Cu I Cu I (μ 2 -OH 2 )L. The switch-over from ET−PT to PT−ET mechanism showcases that the tricopper complex can adopt different PCET mechanisms to circumvent high-barrier proton transfer steps. Overall, three-electron two-proton reduction occurs within a narrow potential range of 170 mV, exemplifying the redox potential leveling effect of secondary proton relays in delivering multiple redox equivalents at metal clusters.

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