Peptide conjugated cellulose nanocrystals with sensitive human neutrophil elastase sensor activity

In chronic wounds, elevated human neutrophil elastase (HNE) is a destructive protease that has been proposed as a biomarker. Numerous wound dressing designs have been introduced in an effort to lower HNE levels. The clinical detection of HNE as a point of care biomarker or an in situ colorimetric adjuvant to chronic wound dressings presents potential advantages in the management of chronic wounds. A colorimetric approach to the detection of HNE using peptide conjugated cotton cellulose nanocrystals (CCN) is reported here. For this purpose a HNE tripeptide substrate, n-Succinyl-Alanine–Alanine-Valine-para-nitroanilide (Suc-Ala–Ala-Val-pNA), was covalently attached to glycine esterified CCN and compared with a similar tetrapeptide analog for colorimetric HNE sensor activity. Visible HNE activity was significantly higher on CCN tripeptide conjugates when compared with similar analogs synthesized on paper. Upon enzymatic release of para-nitroaniline (pNA) from the Glycine-CCN conjugate of succinyl-Ala–Ala-Val-pNA, amplification of the colorimetric response from pNA with reactive dyes enhanced visible absorption of the chromogen. Two color amplifying dyes that react with pNA were compared for their ability to enhance the visual sensor response to HNE activity. The colorimetric detection of HNE with CCN tripeptide conjugates was sensitive at HNE levels previously reported in chronic wound fluid (0.05 U/mL HNE). The HNE sensor and the chromogen amplifying dyes were interfaced with 50 and 10 kD dialysis cellulose membranes (DCM) to model filtration of HNE and chromogen (pNA) from a model wound dressing surface before and after sensor reactivity. The detection sensitivity to HNE activity was assessed with the CCN-tripeptide conjugate interfaced at the DCM surface distal and proximal to a dressing surface. The HNE sensor interfaced proximal to the dressing surface was most efficient with 10 kD membrane filtration of pNA and subsequent reaction with amplifying dyes. When interfaced with the 10 kD cellulose membrane, elastase sensor activity remained sensitive to 0.05 U/mL HNE. The nanocellulose surface properties, performance and design issues of the biosensor approach are discussed.     

Enthalpy increments and thermodynamic functions of rare earth samarium titanates RESmTi<Subscript>2</Subscript>O<Subscript>7</Subscript>(s) (RE = Gd,Dy)

Enthalpy measurements have been taken on GdSmTi₂O₇ and DySmTi₂O₇ by using a high-temperature differential calorimeter at temperature between 800 and 1655 K. Thermodynamic function, such as heat capacity, entropy and Gibbs energy functions of GdSmTi₂O₇ and DySmTi₂O₇, was derived using the data obtained in this study. The results are presented and compared with the data available in the literature. The polynomial expression of enthalpy increments obtained for GdSmTi₂O₇(s) and DySmTi₂O₇(s) in the temperature range 298–1700 K is given as: \(\begin{aligned} H_{\text{T}}^{0} - H_{298}^{0} / {\text{J}}\,{\text{mol}}^{ - 1} & = 252.961\,T \, + 1.596 \times 10^{ - 2} \,T^{2} + 3.705 \times 10^{6} \,T^{ - 1} - 89{,}265\quad ({\text{GdSmTi}}_{2} {\text{O}}_{7} ) \\ H_{\text{T}}^{0} - H_{298}^{0} / {\text{J}}\,{\text{mol}}^{ - 1} & = 256.504\,T \, + 1.576 \times 10^{ - 2} \,T^{2} + 3.531 \times 10^{6} \,T^{ - 1} - 89{,}721\quad \left( {{\text{DySmTi}}_{2} {\text{O}}_{7} } \right). \\ \end{aligned}\)     

Enthalpy increment measurements on europium titanate

Europium titanate is a potential control rod material. Enthalpy increments of europium titanate (Eu₂TiO₅) were measured in the temperature range 770–1,747 K by employing the method of inverse drop calorimetry using a high-temperature differential calorimeter. Thermodynamic functions such as heat capacity, entropy and Gibbs energy function have been computed in the temperature range 298–1,800 K.     

High-temperature calorimetric measurements on RE2TeO6 (RE = Gd,Er)

Journal of Thermal Analysis and Calorimetry - The ternary compounds of Gd2TeO6 (s)&nbsp;and Er2TeO6 (s)&nbsp;were prepared by solid-state route and characterized by XRD, ICP-AES and ICP-MS...     

Thermodynamic properties of uranium plutonium mixed carbides

High plutonium containing hyperstoichiometric mixed carbide fuels are used as driver fuel in the Fast Breeder Test Reactor at Kalpakkam, India. The enthalpy increment of the mixed carbide fuels were measured in the temperature range 1000–1800 K using a high temperature drop calorimeter. The results are presented and compared with the data available in the literature.     

Thermodynamic functions for U0.45Pu0.55N

Enthalpy increments of U_0.45Pu_0.55N were measured in the temperature range of 1025–1775 K by inverse drop calorimetry using a high temperature differential calorimeter. The enthalpy increments were fitted to a polynomial in temperature and the heat capacity, entropy and Gibbs energy functions were computed. The results are presented and discussed in comparison with literature data.     

Al-MCM-48分子筛对苯酚与乙酸异丙酯异丙基化反应的催化性能(英文)

Al-MCM-48 molecular sieves (Si/Al molar ratios = 25, 50, 75, and 100) were synthesized hydrothermally using cetyltrimethyl-ammonium bromide as the structure directing template. The orderly arrangement of mesopores was evident from the low angle X-ray diffraction patterns and transmission electron microscopy images. The catalytic performance of the materials was evaluated in the vapor phase isopropylation of phenol with isopropyl acetate. Phenol conversion decreased with the increase in the Si/Al ratio of the catalysts. The major reaction product was 4-isopropyl phenol with 78% selectivity. The delocalization of phenolic oxygen electron pair over the aromatic ring promoted para-selective alkylation. Such delocalization could be aided by the hydrophilic surface of the molecular sieves. Although an ester was used as the alkylating agent, phenyl isopropyl ether was not formed in the reaction.     

Effect of a nonionic surfactant on Trichoderma cellulase treatments of regenerated cellulose and cotton yarns

It has been shown that some surfactants affect the hydrolysis of cellulose by cellulase. In this study, the effect of the surfactant Tween 20 on the hydrolysis of different cellulosic fibers was investigated and related to the cellulose fiber structure. It was found that this non-ionic surfactant enhanced the enzymatic saccharification of highly crystalline cellulosics such as Avicel, Tencel and cotton but not of cuprammonium rayon. The enhanced saccha-rification effected by the surfactant is attributed to inhibition of non-productive sorption of the endoglucanase of the cellulose surface which gives greater access to the cellulose chain ends by the exoglucanase. Although all three fibers lost tensile strength as a result of the enzymatic treatment, no further decrease was effected by the presence of the surfactant.     

Leveraging Torsional and Steric Strains: A Pre-macrocyclization Strategy Enables Conformation-Specific Fullerene Binding in m-Cyclophanes

Though the chemistry of resorcinarenes is half a century old, the conformationally-locked resorcinarene crowns are generally constructed using hydrogen bonds or covalent tethers. Often, covalent tethering involves extra post-macrocyclization steps involving upper-rim functionalities. We have leveraged the torsional and steric strains through α-substituents of the lower-rim C-alkyl chains and accomplished conformationally-rigid fluorescent m-cyclophane deep-crowns in a predetermined way. The strategy offers a pre-macrocyclization route conserving upper-rim functionalities, an aspect overlooked in resorcinarene chemistry. X-ray structural and computational analyses unveil the cause for conformational rigidity in m-cyclophanes due to α-branching in C-alkyls (linear vs. α-/β-branched). The conformationally-locked fluorescent deep-crown with a preorganized cavity captures hydrophobic spherical guest C₆₀ in both solution and solid states specifically, when compared to conformationally-dynamic boats, enabling conformation-specific binding.