Water‐Soluble Molecularly Imprinted Nanoparticles (MINPs) with Tailored,Functionalized, Modifiable Binding Pockets

Construction of receptors with binding sites of specific size, shape, and functional groups is important to both chemistry and biology. Covalent imprinting of a photocleavable template within surface–core doubly cross‐linked micelles yielded carboxylic acid‐containing hydrophobic pockets within the water‐soluble molecularly imprinted nanoparticles. The functionalized binding pockets were characterized by their binding of amine‐ and acid‐functionalized guests under different pH values. The nanoparticles, on average, contained one binding site per particle and displayed highly selective binding among structural analogues. The binding sites could be modified further by covalent chemistry to modulate their binding properties.     

Fetal hematopoietic stem cells express MFG-E8 during mouse embryogenesis

The milk fat globule-EGF-factor 8 protein (MFG-E8) has been identified in various tissues, where it has an important role in intercellular interactions, cellular migration, and neovascularization. Previous studies showed that MFG-E8 is expressed in different cell types under normal and pathophysiological conditions, but its expression in hematopoietic stem cells (HSCs) during hematopoiesis has not been reported. In the present study, we investigated MFG-E8 expression in multiple hematopoietic tissues at different stages of mouse embryogenesis. Using immunohistochemistry, we showed that MFG-E8 was specifically expressed in CD34⁺ HSCs at all hematopoietic sites, including the yolk sac, aorta-gonad-mesonephros region, placenta and fetal liver, during embryogenesis. Fluorescence-activated cell sorting and polymerase chain reaction analyses demonstrated that CD34⁺ cells, purified from the fetal liver, expressed additional HSC markers, c-Kit and Sca-1, and that these CD34⁺ cells, but not CD34⁻ cells, highly expressed MFG-E8. We also found that MFG-E8 was not expressed in HSCs in adult mouse bone marrow, and that its expression was confined to F4/80⁺ macrophages. Together, this study demonstrates, for the first time, that MFG-8 is expressed in fetal HSC populations, and that MFG-E8 may have a role in embryonic hematopoiesis.     

Cooperative Bond Activation and Catalytic Reduction of Carbon Dioxide at a Group 13 Metal Center

A single‐component ambiphilic system capable of the cooperative activation of protic, hydridic and apolar H? X bonds across a Group 13 metal/activated β‐diketiminato (Nacnac) ligand framework is reported. The hydride complex derived from the activation of H₂ is shown to be a competent catalyst for the highly selective reduction of CO₂ to a methanol derivative. To our knowledge, this process represents the first example of a reduction process of this type catalyzed by a molecular gallium complex.     

Trichosanthes kirilowii ameliorates cisplatin-induced nephrotoxicity in both in vitro and in vivo

The aim of this study was to explore the protective effects of Trichosanthes kirilowii ethanol extract (TKE) against cisplatin-induced acute renal failure (ARF). In the in vitro study, TKE-pretreated porcine kidney cells (PK15) exhibited enhanced cell viability after cisplatin (15 μg mL^? 1) treatment in both MTT and crystal violet assays. PK15 cells pretreated with TKE (50 μg mL^? 1) exhibited increased glutathione content, decreased reactive oxygen species production and ameliorated p53 expression. In vivo study, rats were administered with TKE for 4 weeks before cisplatin (5 mg kg^? 1) injection. TKE (100 mg kg^? 1) decreased blood urea nitrogen and creatinine levels by 24% and 47%, respectively, in comparison with cisplatin-alone group. In addition, TKE pretreatment ameliorated cisplatin-induced oxidative stress, as evidenced by increased antioxidative enzyme levels and decreased lipid peroxidation levels. Moreover, TKE pretreatment reduced histopathological alterations in the kidney with decreased apoptotic cells. Taken together, TKE might be beneficial in treating cisplatin-induced ARF.     

Comparison of Nitrogen Activation on Trinuclear Niobium and Tungsten Sulfide Clusters Nb3Sn and W3Sn (n=0–3): A DFT Study

The reaction of N₂ with trinuclear niobium and tungsten sulfide clusters Nb₃S_n and W₃S_n (n=0–3) was systematically studied by density functional theory calculations with TPSS functional and Def2-TZVP basis sets. Dissociations of N−N bonds on these clusters are all thermodynamically allowed but with different reactivity in kinetics. The reactivity of Nb₃S_n is generally higher than that of W₃S_n. In the favorite reaction pathways, the adsorbed N₂ changes the adsorption sites from one metal atom to the bridge site of two metal atoms, then on the hollow site of three metal atoms, and at that place, the N−N bond dissociates. As the number of ligand S atoms increases, the reactivity of Nb₃S_n decreases because of the hindering effect of S atoms, while W₃S and W₃S₂ have the highest reactivity among four W₃S_n clusters. The Mayer bond order, bond length, vibrational frequency, and electronic charges of the adsorbed N₂ are analyzed along the reaction pathways to show the activation process of the N−N bond in reactions. The charge transfer from the clusters to the N₂ antibonding orbitals plays an essential role in N−N bond activation, which is more significant in Nb₃S_n than in W₃S_n, leading to the higher reactivity of Nb₃S_n. The reaction mechanisms found in this work may provide important theoretical guidance for the further rational design of related catalytic systems for nitrogen reduction reactions (NRR).     

Crystal-to-crystal transitions in nylon M5T

Journal of Thermal Analysis and Calorimetry - Crystal-to-crystal transitions of a high-temperature nylon, poly(2-methtyl pentamethylene terephthalamide, nylon M5T), were studied by conventional and...     

Understanding Behavior of Polycaprolactone–Gelatin Blends under High Pressure CO<Subscript>2</Subscript>

Polycaprolactone (PCL) is widely used in biomedical applications as electrospun fibers or porous foams. As PCL is synthetic polymer, many researchers have explored blends of PCL–gelatin to combine mechanical and bioactive properties of individual components. High pressure carbon dioxide (CO2) has been studied to foam and impregnate many biocompatible polymers. In case of PCL–gelatin blends, certain compositions can be swelled reversibly under high pressure CO₂ without permanent deformation. This allows successful impregnation of PCL–gelatin blends under CO₂. This study summarizes effect of different treatments adopted during impregnation process including high pressure CO2 on several blend compositions of PCL–gelatin blends. Stress relaxation, polymer melting and dissolution were observed during several treatments which affects porosity and scaffold structure significantly. Results summarized in this study will aid in optimum selection of PCL–gelatin blend composition for biomedical applications. Furthermore, CO₂ solubility in polymers is restricted due to thermodynamic limitations but can be altered in the presence of a co-solvent to produce better foams. PCL can be foamed using supercritical CO₂. However, CO₂ foaming of PCL–gelatin blend becomes challenging to simultaneous swelling of PCL and compression of gelatin providing blend structural stability. This study has demonstrated ability of supercritical CO₂ to foam PCL–gelatin blends in presence of water to create porous structure. These foams were subjected post-fabrication crosslinking and supercritical CO₂ without losing porosity of foams. Thus, creating a strategy to use environmentally benign processes to fabricate, crosslink and impregnate porous scaffolds for biomedical applications.     

One step synthesis of indirubins by reductive coupling of isatins with KBH4

One step synthesis of the natural product indirubin by reductive coupling of isatin with KBH₄ is described and a possible mechanism for the reaction is proposed. Eleven indirubin derivatives were obtained easily from the corresponding substituted isatin.     

Dewatering of cellulose nanofibrils using ultrasound

Although cellulose nanomaterials have promising properties and performance in a wide application space, one hinderance to their wide scale industrial application has been associated with their economics of dewatering and drying and the ability to redisperse them back into suspension without introducing agglomerates or lose of yield. The present work investigates the dewatering of aqueous suspensions of cellulose nanofibrils (CNFs) using ultrasound as a potentially low-cost, non-thermal, and scalable alternative to traditional heat-based drying methods such as spray drying. Specifically, we use vibrating mesh transducers to develop a direct-contact mode ultrasonic dewatering platform to remove water from CNF suspensions in a continuous manner. We demonstrate that the degree of dewatering is modulated by the number of transducers, their spatial configuration, and the flow rate of the CNF suspension. Water removal of up to 72 wt.% is achieved, corresponding to a final CNF concentration of 11 wt.% in 30 min using a two-transducer configuration. To evaluate the redispersibility of the dewatered CNF material, we use a microscopic analysis to quantify the morphology of the redispersed CNF suspension. By developing a custom software pipeline to automate image analysis, we compare the histograms of the dimensions of the redispersed dewatered fibrils with the original CNF samples and observe no significant difference, suggesting that no agglomeration is induced due to ultrasonic dewatering. We also perform SEM analysis to evaluate the nanoscale morphology of these fibrils showing a width range of 20 nm–4 um. We estimate that this ultrasound dewatering technique is also energy-efficient, consuming up to 36% less energy than the enthalpy of evaporation per kilogram of water. Together with the inexpensive cost of transducers (<?$1), the potential for scaling up in parallel flow configurations, and excellent redispersion of the dewatered CNFs, our work offers a proof-of-concept of a sustainable CNF dewatering system, that addresses the shortcomings of existing techniques.