Biodegradable Poly(3-hydroxybutyrate) Nanocomposite

This work seeks bringing a technological and social contribution by searching blends and composites of poly(3-hydroxybutyrate) (PHB) and polyethylene widely used in packaging films, and colloidal silica. The mixtures were prepared by extrusion using a single-screw extruder and were analyzed regarding their thermal and mechanical properties and morphology. The results have shown PHB toughness in the studied compositions, which elongation at break was in the range 5–80% compared to 2% for neat PHB. The small amount (0.2 to 0.4%) of added silica seemed to increase in 20% the tensile strength. The thermal degradation by thermogravimetry from room temperature to 800 °C revealed a mixed behavior for the composites between PHB and polyethylene.     

烟酰型辅酶NAD(P)+和NAD(P)H再生的研究进展

大部分氧化还原酶的催化反应需要烟酰型辅酶NAD(P) 和NAD(P)H作为氧化剂或还原剂参与,由于氧化还原酶应用广泛而辅酶价格昂贵,使得辅酶再生逐渐成为研究热点.综述了近年来NAD(P) 和NAD(P)H酶法再生、电化学法及光化学法再生的研究进展,并介绍了各再生技术的应用和开发状况.     

辅酶NAD(P)H模型分子的研究进展

辅酶NAD(P)H在生物体内起着重要的调节作用, 已引起了有机化学工作者极大的兴趣, 尤其是在还原反应的立体选择性上, 人们已经开展了大量的研究工作. 讨论了NAD(P)H模型分子进行立体专一性还原反应的影响因素, 并对NAD(P)H模型分子的研究工作做了总结.     

Ubiquinone‐Rhodol (UQ‐Rh) for Fluorescence Imaging of NAD(P)H through Intracellular Activation

The nicotinamide adenine dinucleotide (NAD) derivatives NADH and NADPH are critical components of cellular energy metabolism and operate as electron carriers. A novel fluorescent ubiquinone‐rhodol derivative (UQ‐Rh) was developed as a probe for NAD(P)H. By using the artificial promoter [(η⁵‐C₅Me₅)Ir(phen)(H₂O)]²⁺, intracellular activation and imaging of NAD(P)H were successfully demonstrated. In contrast to bioorthogonal chemistry, this “bioparallel chemistry” approach involves interactions with native biological processes and could potentially be used to control or investigate cellular systems.     

Towards Recyclable NAD(P)H Regeneration Catalysts

Rh(III)-TsDPEN, an immobilized analog of the well-known [Cp*Rh(bpy)(H₂O)]²⁺ was evaluated as a heterogeneous, recyclable regeneration catalyst for reduced oxidoreductase cofactors [NAD(P)H]. Repeated use of this catalyst was established and the catalytic properties were initially investigated. Apparently, Rh(III)-TsDPEN is prone to severe diffusion limitations, necessitating further developments. Overall, a promising concept for chemoenzymatic redox catalysis is proposed, which may overcome some of the current limitations such as catalyst cost and incompatibility of Rh with some biocatalysts.     

Enzyme-Compatible Core-Shell Nanoreactor for in Situ H2-Driven NAD(P)H Regeneration

The regeneration of the reduced form cofactor NAD(P)H is essential for the extra-cellular application of bio-reduction, which necessitates not only the development of efficient artificial NAD(P)H regeneration catalytic system but also its well compatibility with the cascade enzymatic reduction system. In this work, we reported the preparation of a metal nanoparticle (NP) and metal complex integrated core-shell nanoreactor for H₂-driven NAD(P)H regeneration through the immobilization of a Rh complex on Ni/TiO₂ surface via a bipyridine contained 3D porous organic polymer (POP). In comparison with the corresponding single component metal NPs and the immobilized Rh complex, the integrated catalyst presented simultaneously enhanced activity and selectivity in NAD(P)H regeneration thanks to the rapid spillover of activated H species from metal NPs to Rh complex. In addition, the size-sieving effect of POP precluded the direct interaction of enzyme and Rh complex confined in the pores, enabling the success coupling of core-shell nanoreactor and aldehyde ketone reductase (AKR) for chemoenzymatic reduction of acetophenone to (R)-1-phenylethan-1-ol. This work provides a strategy for the rational manipulation of multicomponent cooperation catalysis.     

细胞内NAD(P)H水平分析技术的研究进展

细胞内NAD(P)H水平直接控制着细胞的衰老、节律、癌变、死亡等重大生命过程,NAD(P)H水平的研究是生命过程中新的研究热点之一.本文介绍了NAD(P)H的结构、特性及检测方法,重点探讨了近年来国内外NAD(P)H水平的检测,并对其研究现状进行了综述.     

Melting temperature evolution of non-reorganized crystals. Poly(3-hydroxybutyrate)

In the present study the correlation between the melting behaviour of poly(3-hydroxybutyrate) (PHB) original, non-reorganized crystals and the crystallinity increase during isothermal crystallization is presented and discussed. Since the reorganization processes modify the melting curve of original crystals, it is necessary to prevent and hinder all the processes that influence and increase the lamellar thickness. PHB exhibits melting/recrystallization on heating, the occurring of lamellar thickening in the solid state being excluded. The first step of the study was the identification of the scanning rate which inhibits PHB recrystallization at sufficiently high T_c. For the extrapolated onset and peak temperatures of the main melting endotherm, which is connected to fusion of dominant lamellae, a double dependence on the crystallization time was found. The crystallization time at which T_onset and T_peak change their trends was found to correspond to the spherulite impingement time, so that the two different dependencies were put in relation with primary and secondary crystallizations respectively. The increase of both T_onset and T_peak at high crystallization times after spherulite impingement was considered an effect due to crystal superheating and an indication of a stabilization process of the crystalline phase. Such stabilization, which produces an increase of the melting temperature, is probably connected with the volume filling that occurs after spherulite impingement.     

NAD(P)+-NAD(P)H models. 90. Stereoselection controlled by electronic effect of a carbonyl group in oxidation of NAD(P)H analog

4-Monodeuterated NAD(P)H model compounds (1,4,6,7-tetrahydro-1,6,11-trimethyl-5-oxo-5H-benzo[c]pyrido[2,3-e]az epin; 11Me-MMPAH) have been oxidized with a series of p-benzoquinone and its derivatives in the presence of Mg2+. The models have an axial chirality with respect to the orientation of carbonyl dipole, the dihedral angle of which is larger than 55 degrees out of the plane of dihydropyridine ring. Without Mg2+, the anti- (with respect to the carbonyl dipole) hydrogen is 3 to 32 times more reactive than the corresponding syn-hydrogen, whereas, when Mg2+ is present in the system, the selectivity is shifted toward the syn-preferency. Mg2+ plays the role of a Lewis acid catalyst to control the stereochemistry at the same time as it catalyzes the reaction.     

烟酰胺辅酶模型对N－芳基芴亚胺的酸催化还原反应的研究

报道了５种Ｎ－芳基芴亚胺在酸性条件下被烟酰胺辅酶模型（Ｈａｎｔｚｓｃｈ酯，ＢＮＡＨ）还原的反应。结果表明：亚胺的结构、酸的强度以及溶剂的不同均会影响亚胺的还原效率，本文结合反应的结构效应、溶剂效应和同位素效应，对其可能的酸催化氢负离子转移机理进行了讨论。     

NAD(P)H辅酶模型物结构与反应性关系的研究──3-位酰基的电子效应

合成了一系列3酰胺基氮取代的NAD(P)H模型物,测定了其与5硝基异喹啉正离子的二级反应速率常数,并与模型物的氧化还原电势进行了比较.实验结果表明,模型物3位酰基氧一方面可离域二氢吡啶环上N的电子;另一方面负电性的3位酰基氧在反应过渡态中又可引起分子内和分子间的两种静电作用;3位酰基的电子效应对模型物动力学反应性的影响是这两种效应综合作用的结果.     

3D Printing of Poly(3-hydroxybutyrate) Porous Structures Using Selective Laser Sintering

Summary: Poly(3-hydroxybutyrate) (PHB) 3D porous cubes were successfully built with Selective Laser Sintering (SLS), one of the many existing 3D printing technologies. The resulting cubes presented shape and dimensions very close to the corresponding virtual model. Moreover, they were resistant to handling without presenting any visible damage. The PHB powder did not present variation in thermal properties and chemical composition after 32.15 hours of SLS process as observed by proton nuclear resonance (¹H NMR) and differential scanning calorimetry (DSC) analysis, indicating that it can be re-utilized to print additional structures without affecting the reproducibility of the process.     

光催化NAD（P）H再生的研究进展

辅酶与酶催化反应紧密相关,是酶催化氧化还原反应过程中不可缺失的重要组成,其中,烟酰胺类辅酶NAD和NADP参与了大多数的酶催化氧化还原反应,是辅酶中最重要的一类。然而,辅酶的高成本限制了其实际应用。因此,烟酰胺辅酶的高效和低成本再生具有特别重要的意义。本文总结了还原型烟酰胺辅酶光催化再生方法的相关研究进展以及各种光敏剂的优缺点,提出了光催化NAD(P)H再生仍需要解决的问题。     

Chemically engineered papain as artificial formate dehydrogenase for NAD(P)H regeneration

Organometallic complexes of the general formula [(η(6)-arene)Ru(N?N)Cl](+) and [(η(5)-Cp*)Rh(N?N)Cl](+) where N?N is a 2,2'-dipyridylamine (DPA) derivative carrying a thiol-targeted maleimide group, 2,2'-bispyridyl (bpy), 1,10-phenanthroline (phen) or ethylenediamine (en) and arene is benzene, 2-chloro-N-[2-(phenyl)ethyl]acetamide or p-cymene were identified as catalysts for the stereoselective reduction of the enzyme cofactors NAD(P)(+) into NAD(P)H with formate as a hydride donor. A thorough comparison of their effectiveness towards NAD(+) (expressed as TOF) revealed that the Rh(III) complexes were much more potent catalysts than the Ru(II) complexes. Within the Ru(II) complex series, both the N?N and arene ligands forming the coordination sphere had a noticeable influence on the activity of the complexes. Covalent anchoring of the maleimide-functionalized Ru(II) and Rh(III) complexes to the cysteine endoproteinase papain yielded hybrid metalloproteins, some of them displaying formate dehydrogenase activity with potentially interesting kinetic parameters.     

Evaluation of the transport properties of Poly(3-hydroxybutyrate) and its 3-hydroxyvalerate copolymers for packaging applications

Poly(3-hydroxybutyrate) (PHB) and ist 3-hydroxyvalerate containing copolymers form a family of fully biodegradable polyesters with many potential applications. In this work, the results obtained in our laboratory concerning carbon dioxide, water and organic solvent transport through PHB and three low 3-hydroxyvalerate copolymers are reviewed. Comparison established between the former results and some data taken from the literature, have revealed that PHB and the above mentioned copolymers show transport properties similar to other common thermoplastics such as PVC and PET, particularly in the case of carbon dioxide and water. Consequently, PHB and copolymers can be catalogued as good barrier materials against these penetrants. On the other hand, these biopolymers show a low barrier character against organic compound permeation. All these features conform a good balance of physicochemical properties for these polyhydroxyalkanoates, which may take them suitable for several applications, including its use in biodegradable packaging materials.     

聚3-己基噻吩的制备及其荧光轨迹的研究

本文以3-己基噻吩为单体,无水FeCl3为氧化剂,在四氢呋喃(THF)中浓缩结晶制备了聚3-己基噻吩(P3HT),通过红外光谱、GPC、XRD和1H NMR表征其结构,测定了经THF浓缩前后P3HT的电流-电压曲线,并采用单分子光谱技术得到了其在介孔纳米TiO2基底上的荧光强度轨迹。结果表明,通过THF浓缩结晶能提高P3HT的相对分子量和其太阳能电池的能量转化效率,并且单分子P3HT/TiO2体系间界面电子的转移是不均一的,不但随着分子的不同而不同,而且还随着时间的不同而不同,其自相关函数呈非指数的衰减。