Search results for "Conjugate"
showing 10 items of 644 documents
Polymorphism-Triggered Reversible Thermochromic Fluorescence of a simple 1,8-Naphthyridine
2013
The fluorescent behavior in the solid state of a naphthyridine-based donor–acceptor heterocycle is presented. Synthesized as a crystalline blue-emissive solid (Pbca), the compound can easily be transformed in its P21/c polymorphic form by heating. The latter material shows blue to cyan emission switching triggered by a reversible thermally induced phase transformation. This fact, the reversible acidochromism, and the strong anisotropic fluorescence of the compound in the solid state, account for the potential of 1,8-naphthyridines as simple and highly tunable organic compounds in materials science.
Synthesis and characterization of polyene chromophores with hydroxyl functionalization
2008
Abstract Eight hydroxyl functionalized donor–acceptor polyene chromophores 3–10 were synthesized and characterized. Knoevenagel condensation reaction of aromatic polyenals with 2-cyanoacetamide derivatives was utilized to synthesize chromophores with all-E configuration. Chromophores of this kind can be attached covalently to polymers or functionalized with dendrons in order to tune the properties. The structures of the molecules were verified by 1H NMR, 13C NMR, ESI-TOF mass spectrometry and UV–vis measurements. Reduced bond-length alternation of the molecules in DMSO-d6 solution were observed by calculating the average difference of the vicinal coupling constants between adjacent CH CH an…
Rapid Self-Healing and Thixotropic Organogelation of Amphiphilic Oleanolic Acid–Spermine Conjugates
2021
Natural and abundant plant triterpenoids are attractive starting materials for the synthesis of conformationally rigid and chiral building blocks for functional soft materials. Here, we report the rational design of three oleanolic acid-triazole-spermine conjugates, containing either one or two spermine units in the target molecules, using the Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition reaction. The resulting amphiphile-like molecules 2 and 3, bearing just one spermine unit in the respective molecules, self-assemble into highly entangled fibrous networks leading to gelation at a concentration as low as 0.5% in alcoholic solvents. Using step-strain rheological measurements, we show ra…
Detoxifying antitumoral drugs via nanoconjugation: the case of gold nanoparticles and cisplatin
2021
Nanoparticles (NPs) have emerged as a potential tool to improve cancer treatment. Among the proposed uses in imaging and therapy, their use as a drug delivery scaffold has been extensively highlighted. However, there are still some controversial points which need a deeper understanding before clinical application can occur. Here the use of gold nanoparticles (AuNPs) to detoxify the antitumoral agent cisplatin, linked to a nanoparticle via a pH-sensitive coordination bond for endosomal release, is presented. The NP conjugate design has important effects on pharmacokinetics, conjugate evolution and biodistribution and results in an absence of observed toxicity. Besides, AuNPs present unique o…
SYNTHESIS, CHARACTERIZATION AND IN VITRO CYTOTOXICITY STUDIES OF A MACROMOLECULAR CONJUGATE OF PACLITAXEL BEARING OXYTOCIN AS TARGETING MOIETY.
2007
The present study describes the experimental synthetic procedure and the characterization of a new polyaspartamide macromolecular prodrug of paclitaxel, bearing oxytocin residues as targeting moieties. In vitro stability studies of bioconjugate, performed in media mimicking biological fluids (buffer solutions at pH 7.4 and 5.5) and in human plasma, evidenced the high stability of the targeting portion (oxytocin)-polymer linkage and the ability of this conjugate to release linked paclitaxel in a prolonged way in plasma. Moreover, preliminary in vitro antiproliferative studies, carried out on MCF-7 cells, that are oxytocin receptor positive cells, showed that the polymeric conjugate has the s…
Milk quality as affected by grazing time of day in Mediterranean goats.
2008
We evaluated the effect of grazing time of day on goat milk chemical composition, renneting properties and milk fatty acid profile in a Mediterranean grazing system. Sixteen lactating Girgentana goats were divided into two experimental groups and housed in individual pens, where they received 500 g/d of barley grain. For 5 weeks the two groups were left to graze in two fenced plots on a ryegrass sward as follows: morning group (AM), from 9·00 to 13·00; afternoon group (PM), from 12·00 to 16·00. In selected herbage, water-soluble carbohydrates (WSC) increased in the afternoon (204 v. 174 g/kg dry matter, DM; P=0·01), whereas crude protein (CP) and linolenic acid decreased (respectively, 16·7…
A thin layer-based amperometric enzyme immunoassay for the rapid and sensitive diagnosis of respiratory syncytial virus infections
2012
Abstract A simple electrochemical sandwich immunoassay involving a polystyrene microarray slide coated with monoclonal capture antibodies and carbon screen-printed sensors (SPS) was designed for the rapid diagnosis of respiratory syncytial virus (RSV). The detection of the antibody-antigen complex formation relied on the use of a horseradish peroxidase conjugate. Its chronoamperometric measurement detection was performed by confining a droplet of H 2 O 2 /3,3',5,5'-tetramethylbenzidine enzyme substrate/mediator solution within a thin layer between one spot of the microarray and the surface of one screen-printed electrochemical cell. The accumulation of the enzyme product in the thin film of…
An analytical solution for multilayered beams subjected to ends loads
2014
An alternative model for multilayered beams undergoing axial, shear and bending loads applied at the beam's ends is developed. It is based on a layer-wise kinematics, which inherently fulfills the equilibrium equations at layer level and the interface continuity conditions. This kinematics is suitably expressed by introducing a set of generalized variables representative of the beam midline displacement field, which become the primary variables of the problem governing equations. As a consequence, the proposed beam model exhibits the computational characteristics of an equivalent single layer model and possesses the accuracy of layer-wise beam theories, as well. Closed form solutions for di…
Multilayer neural networks: an experimental evaluation of on-line training methods
2004
Artificial neural networks (ANN) are inspired by the structure of biological neural networks and their ability to integrate knowledge and learning. In ANN training, the objective is to minimize the error over the training set. The most popular method for training these networks is back propagation, a gradient descent technique. Other non-linear optimization methods such as conjugate directions set or conjugate gradient have also been used for this purpose. Recently, metaheuristics such as simulated annealing, genetic algorithms or tabu search have been also adapted to this context.There are situations in which the necessary training data are being generated in real time and, an extensive tr…
Catalytic Enantioselective Conjugate Alkynylation of β-Aryl-β-trifluoromethyl Enones Constructing Propargylic All-Carbon Quaternary Stereogenic Cente…
2016
The enantioselective conjugate alkynylation of β-aryl-β-trifluoromethyl enones has been carried out using terminal alkynes and diethylzinc in the presence of 3,3'-bis(perfluorophenyl)BINOL as the chiral ligand to give the corresponding ketones bearing a trifluoromethylated propargylic quaternary stereocenter with fair to good enantioselectivities. Enones bearing a bulky 2-naphthyl attached to the carbonyl group provided the best enantioselectivities. The synthetic applicability of the resulting products has been demonstrated with their iodocyclization to form 4H-pyrans.