Nano-sized layered Mn oxides as promising and biomimetic water oxidizing catalysts for water splitting in artificial photosynthetic systems

MnCO3@BSA-ICG nanoparticles as a magnetic resonance/photoacoustic dual-modal contrast agent for functional imaging of acute ischemic stroke

Timely and accurate diagnosis of acute ischemic stroke (AIS) and simultaneous functional imaging of cerebral oxygen saturation (sO₂) are essential to improve the survival rate of stroke patients but remains challenging. Herein, we developed a pH-responsive manganese (Mn)-based nanoplatform as a magnetic resonance/photoacoustic (MR/PA) dual-modal contrast agent for AIS diagnosis. The Mn-based nanoplatform was prepared via a simple and green biomimetic method using bovine serum albumin (BSA) as a scaffold for fabrication of MnCO₃ NPs as the T₁ MR contrast agent and accommodation of indocyanine green (ICG) as the PA probe. The obtained MnCO₃@BSA-ICG NPs were biocompatible and exhibited a pH-responsive longitudinal relaxation rate and a concentration-dependent PA signal. In vivo MR/PA dual-modal imaging demonstrated that MnCO₃@BSA-ICG NPs quickly and efficiently led to the MR/PA contrast enhancements in the infarcted area while not in the normal region, allowing a timely and accurate diagnosis of AIS. Moreover, PA imaging could directly monitor the sO₂ level, enabling a functional imaging of AIS. Therefore, MnCO₃@BSA-ICG NPs could be applied as a potential MR/PA contrast agent for timely and functional imaging of AIS.

Homogeneous photochemical water oxidation with metal salophen complexes in neutral media

The development of water oxidation catalysts based on Earth-abundant metals that can function at neutral pH remains a basic chemical challenge.

Functionalization of Smart Gels with Beta-Cyclodextrin and Release Characteristics to Simulating Drugs

Smart gels have many applications in sensors, actuators, shape memory intelligent devices, recognition, self-healing, drug release, biomimetic soft robot design, biomimetic tactile, neural regeneration, biomimetic membranes, supercapacitor, dye-sensitized solar cells, advanced lithium polymer batteries, environmental fields, biomedical fields, et al. And that cyclodextrins are one of the typical macrocycles with good recognition ability, and endowed with fascinating hydrophobic cavities and hydrophilic surface, which enable the encapsulation of diverse small organic molecules by forming inclusion complexes. In this paper, grafted copolymerization between acrylic acid and N,N-dimethyl acrylamide in the presence of water-soluble cyclodextrins was carried out. The effect of ratio of copolymerization monomer on the grafted polymer was examined. The results indicated that self-crosslinking smart gel with multi-stimuli responsive was obtained by selecting suitable the ratio of copolymerization monomer, its behaviors of swelling/shrinking were examined. The adsorption properties and releasing characteristics of smart gel were performed with simulating drugs. Some meaningful results were obtained. These series grafted copolymer would also be used to modify the surface and interface properties of low-dimensional functional materials or heterostructured nanocomposites for intelligent organic-inorganic functional nanocomposites, some good results were obtained.

Nano-sized Mn3O4 and β-MnOOH from the decomposition of β-cyclodextrin-Mn: 2. The water-oxidizing activities

Nano-sized Mn oxides contain Mn3O4, β-MnOOH and Mn2O3 have been prepared by a previously reported method using thermal decomposition of β-cyclodextrin-Mn complexes. In the next step, the water-oxidizing activities of these Mn oxides using cerium(IV) ammonium nitrate as a chemical oxidant are studied. The turnover frequencies for β-MnO(OH) and Mn3O4 are 0.24 and 0.01-0.17 (mmol O2/mol Mns), respectively. Subsequently, water-oxidizing activities of these compounds are compared to the other previously reported Mn oxides. Important factors affecting water oxidation by these Mn oxides are also discussed.

Development of optically transparent water oxidation catalysts using manganese pyrophosphate compounds

One challenge in artificial photosynthetic systems is the development of active oxygen evolution catalysts composed of abundant elements. The oxygen evolution activities of manganese pyrophosphate compounds were examined in electrochemical and photochemical experiments. Electrocatalysis using calcium-manganese pyrophosphate exhibited good catalytic ability under neutral pH and an oxygen evolution reaction was driven with a small overpotential (η<100 mV). UV-vis diffuse reflectance measurements revealed that manganese pyrophosphates exhibit weak absorption in the visible light region while commonly used oxygen evolution catalysts exhibit intense absorption. Therefore, the efficient light absorption of a photocatalyst was retained even after surface modification with a manganese pyrophosphate, and photochemical oxygen evolution was achieved by using magnesium ferrite modified with manganese pyrophosphate nanoparticles under the illumination of visible light at wavelength of over 420 nm.

Photocatalytic H2 evolution from NADH with carbon quantum dots/Pt and 2-phenyl-4-(1-naphthyl)quinolinium ion

Carbon quantum dots (CQDs) were simply blended with platinum salts (K2PtCl4 and K2PtCl6) and converted into a hydrogen-evolution co-catalyst in situ, wherein Pt salts were dispersed on the surface of CQDs under photoirradiation of an aqueous solution of NADH (an electron and proton source) and 2-phenyl-4-(1-naphthyl)quinolinium ion (QuPh(+)-NA) employed as an organic photocatalyst. The co-catalyst (CQDs/Pt) exhibits similar catalytic reactivity in H2 evolution as that of pure Pt nanoparticles (PtNPs) although the Pt amount of CQDs/Pt was only 1/200 that of PtNPs previously reported. CQDs were able to capture the Pt salt acting as Pt supports. Meanwhile, CQDs act as electron reservoir, playing an important role to enhance electron transfer from QuPh(+)-NA to the Pt salt, which was confirmed by kinetic studies, XPS and HRTEM.

Mn oxide/nanodiamond composite: a new water-oxidizing catalyst for water oxidation

Herein, we reported nanosized Mn oxide/nanodiamond composites as water-oxidizing compounds.

Nanolayered manganese oxides as water-oxidizing catalysts: the effects of Cu(ii) and Ni(ii) ions

We synthesized nanolayered manganese oxides in the presence of copper(ii) or nickel(ii) ions, and considered the water oxidizing activities of them.