Search results for "Biomaterials"

Enthalpies of Mixing of Some Primary Hydrogenated and Fluorinated Alcohols and Sodium Dodecanoate Aqueous Solutions

1993

Abstract The enthalpies of transfer from water to the surfactant solutions ΔH(W → W + S) of some hydrogenated and fiuorinated alkanols and of sodium dodecanoate NaL were determined. In the premicellar region the measurements were carried out as functions of both the additive and the surfactant concentrations in order to evaluate the interaction parameters between the additive and the surfactant molecules. It is shown that in this region, pair, triplet, and quadruplet interaction parameters between unlike solute molecules contribute to ΔH(W → W + S). Within the large uncertainty with which these parameters are determined because of the very narrow surfactant and alcohol concentration interva…

Polyaspartamide-graft- Polymethacrylate Nanoparticles for Doxorubicin Delivery

2011

A new PHEA-IB-PMANa + copolymer has been synthesized and its pH-induced self-assembly has been investigated in an aqueous medium. PHEA-IB-PMANa + formed nanoparticles with diameters from 25 to 50 nm upon protonation of the carboxylic acid moieties dislocated along the grafted polymethacrylate sodium salt side chains. The physico-chemical characterization of the nanoparticles was performed using light scattering, zeta-potential measurements, SEM, and AFM. Doxorubicin-loaded nanoparticles were prepared and drug release profiles were evaluated under conditions mimicking physiological media. A biological characterization was carried out by testing the cytotoxicity on Caco-2 cells, and cellular …

Thermal diffusion of dextran in aqueous solutions in the absence and the presence of urea.

2006

The Ludwig-Soret effect was studied for aqueous solutions of dextran in the temperature range 15T55 degrees C taking into account the effect of the addition of urea. In the absence of urea, the Soret coefficient S(T) changes sign; it is positive for T45.0 degrees C but negative for T45.0 degrees C. The positive sign of S(T) means that the dextran molecules migrate toward the cold side of the fluid; this behavior is typical for polymer solutions, whereas a negative sign indicates the macromolecules move toward the hot side. The addition of urea to the aqueous solution of dextran rises S(T) and reduces the inversion temperature. For 2 M urea the change in the sign of S(T) is observed at T = 2…

Synergy of Axial and Point Chirality to Construct Helical N -Heterotriangulene-Based Supramolecular Polymers

2018

Radioactive labeling of defined HPMA-based polymeric structures using [18F]FETos for in vivo imaging by positron emission tomography.

2009

During the last decades polymer-based nanomedicine has turned out to be a promising tool in modern pharmaceutics. The following article describes the synthesis of well-defined random and block copolymers by RAFT polymerization with potential medical application. The polymers have been labeled with the positron-emitting nuclide fluorine-18. The polymeric structures are based on the biocompatible N-(2-hydroxypropyl)-methacrylamide (HPMA). To achieve these structures, functional reactive ester polymers with a molecular weight within the range of 25,000-110,000 g/mol were aminolyzed by 2-hydroxypropylamine and tyramine (3%) to form (18)F-labelable HPMA-polymer precursors. The labeling procedure…

Cell Adhesive and Antifouling Polyvinyl Chloride Surfaces Via Wet Chemical Modification

2012

Polyvinyl chloride (PVC) is one of the most frequently used polymers for the manufacturing of medical devices. Limitations for its usage are based upon unfavorable surface properties of the polymer including its hydrophobicity and lack of functionalities in order to increase its versatility. To address this issue, wet chemical modification of PVC was performed through surface amination using the bifunctional compound ethylene diamine. The reaction was conducted in order to achieve maximum surface amination while leaving the bulk material unaffected. The initial activation step was characterized by means of various methods including contact angle measurements, colorimetric amine quantificati…

Inverted Solution Processable OLEDs Using a Metal Oxide as an Electron Injection Contact.

2007

A new type of bottom-emission electroluminescent device is described in which a metal oxide is used as the electron-injecting contact. The preparation of such a device is simple. It consists of the deposition of a thin layer of a metal oxide on top of an indium tin oxide covered glass substrate, followed by the solution processing of the light-emitting layer and subsequently the deposition of a high-workfunction (air-stable) metal anode. This architecture allows for a low-cost electroluminescent device because no rigorous encapsulation is required. Electroluminescence with a high brightness reaching 5700 cd m–2 is observed at voltages as low as 8 V, demonstrating the potential of this new a…

Ionic transport characteristics of negatively and positively charged conical nanopores in 1:1, 2:1, 3:1, 2:2, 1:2, and 1:3 electrolytes

2019

We study experimentally the current (I)-voltage (V) curves of 1:1, 2:1, 3:1, 2:2, 1:2, and 1:3 electrolytes in positively and negatively charged conically-shaped pores of nanoscale dimensions. The positive charges are poly(allylamine hydrochloride) chains functionalized on the pore surface by electrostatic interactions while the negative charges are carboxylic acid groups. Under physiological conditions, these fixed-charge groups are ionized and strongly interact with the different monovalent, divalent, and trivalent ions in the pore solution. The current rectification of the I-V curves and the membrane potentials provide fundamental information on the interaction of the pore charge groups …

Physico-chemical investigation of nanostructures in liquid phases: Nickel chloride ionic clusters confined in sodium bis(2-ethylhexyl) sulfosuccinate…

2009

The confinement of finite amounts of nickel chloride in the hydrophilic core of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles dispersed in n-heptane has been investigated by FT-IR, UV-vis-NIR and fluorescence spectroscopies. The analysis of experimental data consistently leads to hypothesize that NiCl(2) forms small size ionic clusters stabilized by a monolayer of oriented surfactant molecules. Due to confinement and interfacial effects, these ionic clusters show peculiar photophysical properties, which are different from those possessed by the bulk material. From NiCl(2)/AOT/n-heptane solutions, by evaporation of the organic solvent, interesting salt/surfactant nanocomposi…

Relationship between conformation and physicochemical properties of polypeptides. I. Synthesis of homo- and co-oligopeptides by the liquid-phase meth…

1980

The synthesis of the following oligo- and co-oligopeptides by the liquid-phase method is described: (L-Met)15 (I), [L-Glu(OBzl)]20 (II), (L-Val)8-Gly (IV), (L-Ile)8-Gly (V), (L-Ile)4-Gly-(L-Ile)4 (VI), (L-Ile)4-Pro-(L-Ile)4 (VII), (L-Met)5-L-Pro-(L-Met)5 (VIII), [L-Glu(OBzl)]7-L-Pro-[L-Glu(OBzl)]7 (IX). The oligomers are covalently bound to bifunctional polyethylene glycol (PEG) and monofunctional PEG-M of Mr 5 × 103−2 × 104. Analytical controls were carried out after each step of synthesis in order to ensure quantitative coupling yields. All products could be obtained in high purity as indicated by amino acid analysis, thin-layer chromatography and chiroptical methods. The solubility of th…