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51.
Li S Bowerman D Marthandan N Klyza S Luebke KJ Garner HR Kodadek T 《Journal of the American Chemical Society》2004,126(13):4088-4089
We describe a novel photolithographic approach to the synthesis of peptoids (oligo-N-substituted glycines). This strategy enables the construction of a spatially addressable peptoid microarray, thus providing a potentially powerful tool for the discovery of protein ligands. 相似文献
52.
Warnick KF Francom SJ Humble PH Kelly RT Woolley AT Lee ML Tolley HD 《Electrophoresis》2005,26(2):405-414
The class of equilibrium gradient methods utilizes the opposition of two forces, at least one of which changes in magnitude with position, to separate and concentrate analytes. The drawback of many methods of this type is that the production of two opposing forces requires in comparison to standard methods, such as capillary electrophoresis, a relatively complex apparatus. In addition, for techniques such as electric field gradient focusing, hydrodynamic flow leads to Taylor dispersion, which limits the attainable concentration factor. We propose a new method, gradient field electrophoresis, which achieves analyte separation and focusing with only one spatially varying force, an electric field gradient. A model for the method is developed and used to analyze peak capacity. Experimental results for a protein (R-phycoerythrin) are given and compared to the model. 相似文献
53.
Topical photodynamic therapy is used for a variety of malignant and pre-malignant skin disorders, including Bowen's Disease and Superficial Basal Cell Carcinoma. A haem precursor, typically 5-aminolevulinic acid (ALA), acting as a prodrug, is absorbed and converted by the haem biosynthetic pathway to photoactive protoprophyrin IX (PpIX), which accumulates preferentially in rapidly dividing cells. Cell destruction occurs when PpIX is activated by an intense light source of appropriate wavelength. Topical delivery of ALA avoids the prolonged photosensitivity reactions associated with systemic administration of photosensitisers but its clinical utility is influenced by the tissue penetration characteristics of the drug, its ease of application and the stability of the active agent in the applied dose. This review, therefore, focuses on drug delivery applications for topical, ALA-based PDT. Issues considered in detail include physical and chemical enhancement strategies for tissue penetration of ALA and subsequent intracellular accumulation of PpIX, together with formulation strategies and drug delivery design solutions appropriate to various clinical applications. The fundamental aspects of drug diffusion in relation to the physicochemical properties of ALA are reviewed and specific consideration is given to the degradation pathways of ALA in formulated systems that, in turn, influence the design of stable topical formulations. 相似文献
54.
A method using capillary electrophoresis-mass spectrometry (CE-MS) was developed for the structural elucidation of bupivacaine and metabolites in rat urine. Prior to CE-MS analysis, solid-phase extraction (SPE) was used for sample cleanup and preconcentration purposes. Exact mass and tandem mass spectrometric (MS/MS) experiments were performed to obtain structural information about the unknown metabolites. Two instruments with different mass analyzers were used for mass spectrometric detection. A quadrupole time-of-flight (Q-TOF) and a magnetic sector hybrid instrument were coupled to CE and used for the analysis of urine extracts. Hydroxybupivacaine as well as five other isomerically different metabolites were detected including methoxylated bupivacaine. 相似文献
55.
The reactivity of W(NPh)(o-(Me3SiN)2C6H4)(py)2 and W(NPh)(o-(Me3SiN)2C6H4)(pic)2 (py=pyridine; pic=4-picoline) with unsaturated substrates has been investigated. Treatment of W(NPh)(o-(Me3SiN)2C6H4)(py)2 with diphenylacetylene or 2,3-dimethyl-1,3-butadiene generates W(NPh)(o-(Me3SiN)2C6H4)(eta2-PhCCPh) and W(NPh)(o-(Me3SiN)2C6H4)(eta4-CH2=C(Me)C(Me)=CH2), respectively, while the addition of ethylene to W(NPh)(o-(Me3SiN)2C6H4)(py)2 generates the known metallacycle W(NPh)(o-(Me3SiN)2C6H4)(CH2CH2CH2CH2). The addition of 2 equiv of acetone to W(NPh)(o-(Me3SiN)2C6H4)(pic)2 provides the azaoxymetallacycle W(NPh)(o-(Me3SiN)2C6H4)(OCH(Me)2)(OC(Me)2-o-C5H3N-p-Me), the result of acetone insertion into the ortho C-H bond of picoline. Similarily, the addition of 2 equiv of RC(O)H [R=Ph, tBu] to W(NPh)(o-(Me3SiN)2C6H4)(py)2 generates W(NPh)(o-(Me3SiN)2C6H4)(OCH2R)(OCHR-o-C5H4N) [R=Ph, tBu,]. In contrast, reaction between W(NPh)(o-(Me3SiN)2C6H4)(py)2 and 2-pyridine carboxaldehyde yields the diolate W(NPh)(o-(Me3SiN)2C6H4)(OCH(C5H4N)CH(C5H4N)O). The synthesis of W(NPh)(o-(Me3SiN)2C6H4)(PMe3)(py)(eta2-OC(H)C6H4-p-Me), formed by the addition of p-tolualdehyde to a mixture of W(NPh)(o-(Me3SiN)2C6H4)(py)2 and PMe3, suggests that an eta2-aldehyde intermediate is involved in the formation of the azaoxymetallacycle, while the isolation of W(NPh)(o-(Me3SiN)2C6H4)(Cl)(OC(Me)(CMe3)-o-C5H4N), formed by the reaction of pinacolone with W(NPh)(o-(Me3SiN)2C6H4)(py)2, in the presence of adventitious CH2Cl2, suggests that the reaction proceeds via the hydride W(NPh)(o-(Me3SiN)2C6H4)(H)(OC(Me)(CMe3)-o-C5H4N). 相似文献
56.
57.
[reaction: see text] Formal heterolytic activation of elemental hydrogen under Rh catalysis enables the reductive generation of enolates from enones under hydrogenation conditions. Enolates generated in this fashion participate in catalytic C-C bond formation via carbonyl addition to aldehyde and, as demonstrated in this account, ketone partners. Notably, the use of appendant dione partners enables diastereoselective formation of cycloaldol products possessing 3-stereogenic centers, including 2-contiguous quaternary centers. 相似文献
58.
UVB/UVA radiation activates a 48 kDa myelin basic protein kinase and potentiates wound signaling in tomato leaves 总被引:10,自引:0,他引:10
We investigated the effect of UV radiation on early signaling events in the response of young tomato plants (Lycopersicon esculentum) to wounding. Ultraviolet-C (< 280 nm) and UVB/UVA (280-390 nm) radiation both induced 48 kDa myelin basic protein kinase activity in leaves. The activation was associated with phosphorylation of tyrosine residues on the kinase, which is indicative of protein kinases of the mitogen-activated protein kinase family. Ultraviolet-C irradiation resulted in a strong proteinase inhibitor synthesis, as reported previously (Conconi et al., Nature 383, 826-829, 1996). Under the conditions used, UVB/UVA radiation did not induce proteinase inhibitor synthesis but resulted in a strong potentiation of systemic proteinase inhibitor synthesis in response to wounding. The UVB/UVA-irradiated plants that were subsequently wounded accumulated 2.5-4-fold higher levels of proteinase inhibitor I when compared to wounded non-irradiated plants. The potentiating effect was most prominent in the systemic unwounded leaf of a wounded plant. Levels of 12-oxo-phytodienoic acid and jasmonic acid that have been well documented to increase in response to wounding were not detected in response to UVB/UVA irradiation alone. The effect of UVB/UVA radiation in potentiating plant defense signaling should be further considered as a factor that may influence the ecological balance between plants and their predators. 相似文献
59.
MacArthur R Sazinsky MH Kühne H Whittington DA Lippard SJ Brudvig GW 《Journal of the American Chemical Society》2002,124(45):13392-13393
Spin-labeled Cys89 of the soluble methane monooxygenase regulatory protein (MMOB) from Methylococcus capsulatus (Bath) binds within 15 +/- 4 A of the hydroxylase (MMOH) diiron center, placing the MMOB docking site in the MMOH "canyon" region on iron-coordinating helices E and F of the alpha-subunit. 相似文献
60.
Shunjie Liu Yuanyuan Li Ryan T. K. Kwok Jacky W. Y. Lam Ben Zhong Tang 《Chemical science》2021,12(10):3427
Aggregation-induced emission (AIE) is a cutting-edge fluorescence technology, giving highly-efficient solid-state photoluminescence. Particularly, AIE luminogens (AIEgens) with emission in the range of second near-infrared window (NIR-II, 1000–1700 nm) have displayed salient advantages for biomedical imaging and therapy. However, the molecular design strategy and underlying mechanism for regulating the balance between fluorescence (radiative pathway) and photothermal effect (non-radiative pathway) in these narrow bandgap materials remain obscure. In this review, we outline the latest achievements in the molecular guidelines and photophysical process control for developing highly efficient NIR-II emitters or photothermal agents with aggregation-induced emission (AIE) attributes. We provide insights to optimize fluorescence efficiency by regulating multi-hierarchical structures from single molecules (flexibilization) to molecular aggregates (rigidification). We also discuss the crucial role of intramolecular motions in molecular aggregates for balancing the functions of fluorescence imaging and photothermal therapy. The superiority of the NIR-II region is demonstrated by fluorescence/photoacoustic imaging of blood vessels and the brain as well as photothermal ablation of the tumor. Finally, a summary of the challenges and perspectives of NIR-II AIEgens for in vivo theranostics is given.Structural and process controls of NIR-II AIEgens realize manipulating of radiative (R) and nonradiative (NR) decay for precise theranostics. 相似文献