Influence of Cell Disruption and Elution on Cellulase Release of Clostridium straminisolvens (CSK1)

Clostridium straminisolvens (CSK1) is a novel cellulolytic bacterium isolated from a cellulose-degrading bacterial community MC1. In this study, the influence of the following cell disruption and elution methods on CSK1cellulase release was investigated: (1) freezing–thawing, (2) ultrasonication, (3) elution, (4) freezing–thawing following elution, (5) ultrasonication following elution, and lastly (6) high-pressure homogenization following elution. The activity of the cellulases CMCase, β-glucosidase, Avicelase, FPase, and xylanase in crude extracts increased 81.5, 23.8, 87.7, 46.3, and 51.7 %, respectively, with an observed optimal treatment method for each cellulase type. The release of protein from CSK1 cells increased following either cell disruption or elution and was highest at 88.3 % in the homogenization high pressure following elution treatment. A newly observed protein was present following cell elution. The performance of cell elution as determined by real time-PCR indicated that the first time cell elution removed more than 90 % of the CSK1 cells from the substrate. These findings demonstrate that cell disruption and elution are effective methods for inducing cellulase release, and elution is the key step for CSK1. To our knowledge, this study presents the first evidence of optimal treatments for induction of cellulase release of Clostridium straminisolvens. This information will be of great value for use in subsequent efforts to better understand the cellulase characteristics of CSK1 and cellulose degradation mechanisms of the MC1 community.     

Preparation of novel magnetic fluorescent microspheres from copperas and fluorescence enhancement with zinc ions

The aim of this study is to develop a new method for the preparation of Fe₃O₄@SiO₂–An NPs from copperas. The core–shell structures of the nanoparticles and chemical composition have been confirmed by TEM, XRD and FTIR techniques. Fluorescence Enhancement of Fe₃O₄@SiO₂–An NPs with zinc ions was investigated by fluorescence emission spectra. The results indicated that the Fe₃O₄ NPs with a high purity (Total Fe 72.16 %) were obtained from copperas by chemical co-precipitation method and have a uniform spherical morphology with an average diameter of about 10 nm. The Fe₃O₄ NPs coated with silica nanoparticles were prepared, and an attempt had been made that the Fe₃O₄@SiO₂ NPs were modified by 3-aminopropyltriethoxysilane and 9-anthranone successively. The recommended mole ratio of ethanol to water and the content of ammonia water added were 4:1 and 25 wt% respectively, which have an obviously effect on the combination of the final well-ordered MNPs with the amino functionalities and reactant components. The functionalized Fe₃O₄@SiO₂–An NPs have a fluorescence property and this fluorescence effect can be enhanced with the Zn²⁺ ions attachment. Meanwhile, the saturated magnetization of Fe₃O₄@SiO₂–An NPs was 37.8 emug^?1 at 25 °C and this fluorescent material exhibited excellent magnetic properties. A new way was therefore provided for the comprehensive utilization of the unmarketable copperas. Moreover, the functionalized Fe₃O₄@SiO₂–An NPs have a big potential in environmental decontamination, medical technology and biological science.     

Atomic-Scale Insight into Exsolution of CoFe Alloy Nanoparticles in La0.4Sr0.6Co0.2Fe0.7Mo0.1O3−δ with Efficient CO2 Electrolysis

In situ exsolution of metal nanoparticles in perovskite under reducing atmosphere is employed to generate a highly active metal–oxide interface for CO₂ electrolysis in a solid oxide electrolysis cell. Atomic-scale insight is provided into the exsolution of CoFe alloy nanoparticles in La_0.4Sr_0.6Co_0.2Fe_0.7Mo_0.1O_3−δ (LSCFM) by in situ scanning transmission electron microscopy (STEM) with energy-dispersive X-ray spectroscopy and DFT calculations. The doped Mo atoms occupy B sites of LSCFM, which increases the segregation energy of Co and Fe ions at B sites and improves the structural stability of LSCFM under a reducing atmosphere. In situ STEM measurements visualized sequential exsolution of Co and Fe ions, formation of CoFe alloy nanoparticles, and reversible exsolution and dissolution of CoFe alloy nanoparticles in LSCFM. The metal–oxide interface improves CO₂ adsorption and activation, showing a higher CO₂ electrolysis performance than the LSCFM counterparts.     

Rhombicuboctahedral Ag100: Four-Layered Octahedral Silver Nanocluster Adopting the Russian Nesting Doll Model

Precise atomic structure of metal nanoclusters (NCs) is fundamental for elucidating the structure–property relationships and the inherent size-evolution principles. Reported here is the largest known FCC-based (FCC=face centered cubic) silver nanocluster, [Ag₁₀₀(SC₆H₃^3,4F₂)₄₈(PPh₃)₈]⁻: the first all-octahedral symmetric nesting Ag nanocluster with a four-layered Ag₆@Ag₃₈@Ag₄₈S₂₄@Ag₈S₂₄P₈ structure, consistent symmetry elements, and a unique rhombicuboctahedral morphology distinct from theoretical predictions and previously reported FCC-based Ag clusters. DFT studies revealed extensive interlayer interactions and degenerate frontier orbitals. The FCC-based Russian nesting doll model constitutes a new platform for the study of the size-evolution principles of Ag NCs.     

Fe-Co Alloyed Nanoparticles Catalyzing Efficient Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol in Water

Selective hydrogenation of C=O against the conjugated C=C in cinnamaldehyde (CAL) is indispensable to produce cinnamyl alcohol (COL). Nonetheless, it is challenged by the low selectivity and the need to use organic solvents. Herein, for the first time, we report the use of Fe-Co alloy nanoparticles (NPs) on N-doped carbon support as a selective hydrogenation catalyst to efficiently convert CAL to COL. The resultant catalyst with the optimized Fe/Co ratio of 0.5 can achieve an exceptional COL selectivity of 91.7 % at a CAL conversion of 95.1 % in pure water medium under mild reaction conditions, ranking it the best performed catalyst reported to date. The experimental results confirm that the COL selectivity and CAL conversion efficiency are, respectively promoted by the presence of Fe and Co, while the synergism of the alloyed Fe-Co is the key to concurrently achieve high COL selectivity and CAL conversion efficiency.     

Conjugated polymer nanoparticles as fluorescence switch for selective cell imaging

Fluorescence switch plays a vital role in bioelectronics and bioimaging.Herein,we presented a new kind of facile electrostatic complex nanoparticles(ECNs)for fluorescence switching in cells and marking of individual cell.The ECNs were prepared by mixing positively charged poly(6-(2-(thiophen-3-yl)ethoxy)hexyl trimethylammonium bromide)(PT)and negatively charged diarylethene sodium salt(DAECOONa).DAE-COONa is a photoswitchable molecule which can be transformed between the ring-closed fo rm and ring-open form under the irradiation of UV or visible light.The closed-form of DAE-COONa can efficie ntly quench the fluorescence of PT through intermolecular energy transfer,while the open form of DAE-COONa does not influence the emission of PT.Thus,the fluorescence of ECNs can be modulated by light irradiation,and the ECNs with good fluorescence switching performance have been employed for fluorescence imaging and individual cell lighting up process successfully.We demonstrate that the electrostatic complex strategy provides a facile method to construct fluorescence switch fo r selective cell marking and imaging applications.     

The theoretical study of dehydrogenation mechanism from Sr(NH2BH3)2

Structural Chemistry - A first-principle study of dehydrogenation mechanism from Sr(NH2BH3)2 was performed. Three different pathways were explored for Sr(NH2BH3)2 monomer, and the most favorable...     

Chromatographic study of four sesquiterpenoids in volatile oil of Curcumae Rhizoma on reverse phase stationary phase with methyl-β-cyclodextrin as mobile additive

Abstract

The elution behavior of four sesquiterpenoids in volatile oil of Curcumae Rhizoma on reverse-phase high-performance liquid chromatography with methyl-β-cyclodextrin as mobile phase additive was studied, including germacrone, curzerene, furanodiene, and β-elemene. Stoichiometric ratio and apparent formation constants of inclusion complex formed by methyl-β-cyclodextrin and each analyte were calculated by varying the concentration of the additive in the mobile phase composed of methanol and water (90:10, v/v), in which the association constant for inclusion complex formed by the organic modifier methanol and methyl-β-cyclodextrin was also determined. Results showed that the stoichiometric ratio of all the inclusion complex was 1:1 when 0–9?mmol L^?1 of methyl-β-cyclodextrin was added in the mobile phase. Unusual retention behavior of the analyte germacrone was found, which was further investigated by the calculation of thermodynamic parameters. Meanwhile, enthalpy and entropy of the inclusion complexes and solute-stationary phase interactions were determined by linear van’t Hoff plots.     

A Coordinative Dendrimer Achieves Excellent Efficiency in Cytosolic Protein and Peptide Delivery

Cytosolic protein delivery is a prerequisite for the development of protein therapeutics that act on intracellular targets. Proteins are generally membrane‐impermeable and thus need a carrier such as a polymer to facilitate their internalization. However, the efficient binding of proteins with different isoelectric points to polymeric carriers is challenging. In this study, we designed a coordinative dendrimer to solve this problem. The dendrimers modified with dipicolylamine/zinc(II) complex were capable of binding proteins through a combination of ionic and coordination interactions. The best polymer efficiently delivered 30 cargo proteins and peptides into the cytosol, while maintaining their bioactivity after intracellular release. The removal or replacement of zinc ions in the polymer with other transition‐metal ions lead to significantly decreased efficiency in cytosolic protein delivery. This study provides a new strategy to develop robust and efficient polymers for cytosolic protein delivery.