Interfacial Molecular Assemblies of Metalloporphyrins with Two Trans or One Axial Ligands

Molecular assemblies of metalloporphyrins trans‐dichloro(5,10,15,20‐tetra‐p‐tolylporphyrinato)tin(IV) (SnCl2TPPMe) and trans‐dihydroxo(5,10,15,20‐tetra‐p‐tolylporphyrinato)tin(IV) (Sn(OH)2TPPMe), which have two trans axial ligands, as well 5,10,15,20‐tetrakis(4‐methoxyphenyl)‐21H,23H‐porphine iron(III) chloride (FeClTPPOMe) and 5,10,15,20‐tetraphenyl‐21H,23H‐porphine manganese(III) chloride (MnClTPP), which have one axial ligand, are interfacially organized by Langmuir and Langmuir–Blodgett (LB) techniques. SnCl2TPPMe and Sn(OH)2TPPMe form nanofibrous structures which can display distinct supramolecular chirality, although the molecular units themselves are achiral, while FeClTPPOMe and MnClTPP form irregular nanoparticles that display negligible supramolecular chirality. An interpretation in terms of the effects of the axial ligands is proposed for this interesting phenomenon. Moreover, compared with assemblies of the diprotonated free‐base porphyrins, which are fabricated by interfacial (air/2.4 M HCl) organization of free‐base porphyrin, those of SnCl2TPPMe and Sn(OH)2TPPMe display higher stability in terms of supramolecular chirality. These results indicate that the assembly properties of metalloporphyrins can essentially be affected by the axial ligands that are attached to their chromophores, and that stable chiral porphyrin supramolecular associations can be easily produced by using achiral metalloporphyrins bearing two trans axial ligands.     

Characterization and sequence identification of angiotensin II by a novel method involving ultra-fast liquid chromatography assay coupled with matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight five tandem mass spectrometry analysis

High-throughput proteomics aims to investigate dynamically changing proteins expressed by a full organism, specific tissue or cellular compartment under certain conditions. High-sensitivity mass spectrometry has gradually become a significant tool for characterizing peptides. Here, we analyzed angiotensin II using ultra-fast liquid chromatography (UFLC) coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS). First, we applied UFLC in isolating and collecting the angiotensin II, and then Axima-Resonance (MALDI-QIT-ToF MS(5)) was adopted, which enables collision-induced dissociation-MS(5) analysis for fine structural characterization of angiotensin II. Resultant MS, MS(2), MS(3) and MS(4) spectra of interested [M+H](+) ions selected as precursor ions yielded detailed information about the sites of fragmentation as well as the amino acid sequence for angiotensin II; meanwhile, the average deviation between theoretical mass and actually measured mass from MS to MS(5) spectra was only 0.32 Da. It indicated that Axima-Resonance was capable of analyzing the peptide sequence accurately and provide the corresponding fragmentation information thoroughly, thus suggesting a potential strategy involving UFLC assay coupled with MALDI-QIT-ToF MS(5) analysis on high-throughput proteomics study in future.     

Preparative isolation and purification of anti‐tumor agent ansamitocin P‐3 from fermentation broth of Actinosynnema pretiosum using high‐performance counter‐current chromatography

Ansamitocin P‐3 is a potent anti‐tumor maytansinoid found in Actinosynnema pretiosum. However, due to the complexity of the fermentation broth of Actinomycete, how to effectively separate ansamitocin P‐3 is still a challenge. In this study, both analytical and preparative high‐performance counter‐current chromatography were successfully used to separate and purify ansamitocin P‐3 from fermentation broth. A total of 28.8 mg ansamitocin P‐3 with purity of 98.4% was separated from 160 mg crude sample of fermentation broth in less than 80 min with the two‐phase solvent system of hexane–ethyl acetate–methanol–water (0.6:1:0.6:1, v/v/v/v). The purity and structural identification were determined by HPLC, ¹H NMR, ¹³C NMR and mass spectroscopy.     

Efficient isolation and purification of five products from microbial biotransformation of cinobufagin by high‐speed counter‐current chromatography

An efficient separation method of using high‐speed counter‐current chromatography was successfully established to directly purify cytotoxic transformed products of cinobufagin by Cordyceps militaris. The two‐phase solvent system composed of n‐hexane–ethyl acetate–methanol–water (4:6:3:4, v/v) was used in high‐speed counter‐current chromatography. A total of 9 mg of 4β,12α‐dihydroxyl‐cinobufagin ( 1 ), 15 mg of 12β‐hydroxyl‐cinobufagin ( 2 ), 8 mg of 5β‐hydroxyl‐cinobufagin ( 3 ), 12 mg of deacetylcinobufagin ( 4 ) and 6 mg of 3‐keto‐cinobufagin ( 5 ) were obtained in a one‐step separation from 400 mg of the crude extract with purity of 98.7, 97.2, 90.6, 99.1 and 99.4%, respectively, as determined by HPLC. Their chemical structures were identified on the basis of ¹H‐NMR and ¹³C‐NMR technology. All products ( 1 – 5 ) showed the potent activities against human carcinoma cervicis (Hela) and malignant melanoma (A375) cells in vitro.     

Sustained and Extended Release with Structural and Activity Recovery of Lysozyme from Complexes with Sodium (Sulfamate Carboxylate) Isoprene/Ethylene Oxide Block Copolymer

The complexation of lysozyme and sodium (sulfamate carboxylate) isoprene/ethylene oxide (SCIEO) at pH = 7.4 and the release of lysozyme from the complexes in the presence of NaCl were investigated. Through electrostatic and hydrophobic interactions, lysozyme and SCIEO form stable complex nanoparticles. The complexation partially disturbs the structure of lysozyme. Some of the hydrophobic residues of lysozyme are exposed to bind with SCIEO. The complexation leads to loss of most of the lysozyme activity. In the presence of NaCl, lysozyme can be released from the complexes. The released lysozyme molecules recover their native structure and activity completely. In the condition of physiological pH and ionic strength, a sustained and extended release of lysozyme was achieved.

     

Analytical characterization of cell–asbestos fiber interactions in lung pathogenesis

Asbestos is a fiber causing lung diseases such as asbestosis and mesothelioma. Although the process involving these diseases remains to be elucidated for developing drugs and treatments, direct consequences of fiber exposure in humans have been clearly demonstrated. These diseases are first characterized by histological heterogeneity and combine chronic inflammation with fibrosis and cellular alterations. As a consequence, asbestosis is usually diagnosed at advanced stages of the disease and treatments are usually inefficient to cure the patients. Here, we review the links established between asbestos fiber chemistry and morphology with the occurrence of associated lung diseases. Cytological and histological aspects of diseases are described with respect to current analytical capabilities, notably for microscopy techniques.     

Two-photon absorption of photochromic diarylethene and its application to rewritable holographic recording

A new photochromic diarylethene (1a) has been prepared. Both its photochromic behavior and nonlinear optical properties are investigated. 1a shows excellent ring-opening (λ_max = 386 nm) and ring-closing (λ_max = 652 nm) photoisomerization with UV-Vis light irradiation. With 800 nm femtosecond pulsed laser irradiation, 1a shows two-photon-induced photoisomerization, and a two-photon absorption cross-section (σ = 423×10⁵⁰ cm⁴·s per photon) is obtained by using two-photon induced fluorescence method. The applications of two-photon absorption of 1a to holographic recording has been also investigated. A two-photon induced micro-pattern is recorded on the diarylethene 1a-PMMA film with an femtosecond laser of 800 nm, 100 fs, 1 kHz, 50 mW.     

Polarization holographic optical recording based on a new photochromic diarylethene compound

A new unsymmetrical photochromic diarylethene, namely1-[2-methyl-5-(p-N,N-dimethylaminophenyl)-3-thienyl]-2-[2-methyl-5-(3-methoxylphenyl)-3-thienyl] perfluorocyclopentene (1a), was synthesized. The compound showed good photochromism, high sensitivity and remarkable fatigue-resistance both in solution and in poly(methyl methacrylate) (PMMA) matrix with UV/Vis light irradiation. The absorption maximum of its closed-ring isomer was observed at 624 nm in PMMA amorphous film. It is a nice match for the wavelength of the recording laser (633 nm). Using this target compound as recording medium, four types of polarization holographic optical recordings were performed successfully using a He-Ne laser. The results showed that only the orthogonal circular polarization recording could obtain a hologram with high diffraction efficiency and high signal-to noise-ratio. With multiplexing recording technology, three types of polarization multiplexing holographic optical recordings, including angular multiplexing, polarization multiplexing, and angular plus polarization multiplexing holographic recording, were also carried out perfectly based on its photoinduced anisotropic phenomenon accompanying the photochromic reaction by photoirradiation. The results demonstrate that the multiplexing recording technology is an effective method to improve recording capacity when using diarylethene 1 as recording medium.     

Synthesis,characterization, and crystallization of thermoplastic aromatic semi‐crystalline poly(ester‐imide)s based on bis(trimellitic acid anhydride) phenyl ester

A high molecular weight aromatic homopoly(ester‐imide) (homoPEI) was synthesized from homopoly(ester‐amic acids) (homoPEAA), which was obtained from the reaction of bis(trimellitic acid anhydride) phenyl ester (BTAH) with 4‐4'‐oxydianiline ether (ODA). This homoPEI was melt‐processable semi‐crystalline polymer and displayed dual endothermic transitions which were attributed to the different levels of crystal perfection and size in the crystal structures. Four high molecular weight aromatic copoly(ester‐imide)s (coPEIs) were synthesized via copoly(ester‐amic acids)s (coPEAA) from the reaction of 4, 4'‐oxydiphthalic anhydride (ODPA) and BTAH with ODA. The molar percentage of BTAH varied from 10 to 40%. When the molar percentages of BTAH were 30 and 40%, the resulting two coPEIs were crystallinable and their melting temperatures were 361°C and 356/371°C, respectively. Differential scanning calorimetry (DSC) and wide angle X‐ray diffraction (WAXD) results indicated that the crystal structures included short segments of BTAH/ODA and ODPA/ODA. The initial crystallization of the two coPEIs took place during imidization process. Thermogravimetric (TA) and mechanical analysis confirmed that both homoPEI and coPEIs showed almost no weight loss until 400°C in N₂ and good mechanical properties. Copyright © 2009 John Wiley & Sons, Ltd.     

Disassembly of conjugated polyelectrolyte aggregates and their application for colorimetric detection of surfactants in water

A colorimetric strategy based on conjugated polyelectrolyte aggregates has been applied to determine and distinguish anionic, cationic and non-ionic surfactants.