Search results for "Surface Chemistry"
showing 10 items of 721 documents
Design, characterization and in vitro evaluation of 5-aminosalicylic acid loaded N-succinyl-chitosan microparticles for colon specific delivery
2011
The objective of this study was to prepare NS-chitosan microparticles for the delivery of 5-aminosalicylic acid (5-ASA) to the colon. Microparticles can spread out over a large area of colon allowing a more effective local efficacy of 5-ASA. N-Succinyl-chitosan was chosen as carrier system because of its excellent pharmaceutical properties in colon drug targeting such as poor solubility in acid environment, biocompatibility, mucoadhesive properties, and low toxicity. It was prepared by introducing succinic group into chitosan N-terminals of the glucosamine units. 5-ASA loaded NS-chitosan microparticles were prepared using spray-drying. As a control, a matrix obtained by freeze-drying techni…
Characterization and biodistribution of Au nanoparticles loaded in PLGA nanocarriers using an original encapsulation process
2021
Due to their imaging and radiosensitizing properties, ultrasmall gadolinium chelate-coated gold nanoparticles (AuNP) represent a promising approach in the diagnosis and the treatment of tumors. However, their poor pharmacokinetic profile, especially their rapid renal clearance prevents from an efficient exploitation of their potential for medical applications. The present study focuses on a strategy which resides in the encapsulation of AuNP in large polymeric NP to avoid the glomerular filtration and then to prolong the vascular residence time. An original encapsulation procedure using the polyethyleneimine (PEI) was set up to electrostatically entrap AuNP in biodegradable poly(lactic-co-g…
Poloxamer/sodium cholate co-formulation for micellar encapsulation of Doxorubicin with high efficiency for intracellular delivery: an in-vitro bioava…
2020
Abstract Hypothesis Doxorubicin hydrochloride (DX) is widely used as a chemotherapeutic agent, though its severe side-effects limit its clinical use. A way to overcome these limitations is to increase DX latency through encapsulation in suitable carriers. However, DX has a high solubility in water, hindering encapsulation. The formulation of DX with sodium cholate (NaC) will reduce aqueous solubility through charge neutralization and hydrophobic interactions thus facilitating DX encapsulation into poloxamer (F127) micelles, increasing drug latency. Experiments DX/NaC/PEO-PPO-PEO triblock copolymer (F127) formulations with high DX content (DX-PMs) have been prepared and characterized by scat…
Modification of halloysite lumen with dopamine derivatives as filler for antibiofilm coating
2023
Hypothesis: Development of nanocomposite coating with antibiofilm properties is of fundamental importance to efficient fight biofilm formation preventing infections in biomedical area. In this context, halloysite nanotubes (HNTs), biocompatible and low-cost clay mineral, have been efficiently used as filler for different polymeric matrices affording several nanocomposites with appealing antimicrobial properties. The modification of HNTs surfaces represents a valuable strategy to improve the utilization of the clay for biological purposes. Experiments: Herein, the covalent modification of the HNTs lumen with properly designed dopamine derivatives with different perfluoroalkyl chain length is…
Saving time when measuring BET isotherms.
2007
The measurement of adsorption isotherms and the detn. of surface properties of a solid by means of the BET equation usually takes a lot of time as it involves measurement of several dynamic adsorption curves each at a given gas pressure. Two different timesaving approaches are suggested: (a) the beginning of a single dynamic curve is considered and (b) the beginnings of a no. of different dynamic curves is considered. Approach (a) is less time consuming than approach (b), where approach (b) yields more accurate ests. of the BET-parameters. A discussion is given of the possibilities of using the time saving procedure of Jaentti for the two approaches. [on SciFinder (R)]
One-Pot Synthesis and AFM Imaging of a Triangular Aramide Macrocycle
2014
Macrocyclizations in exceptionally good yields were observed during the self-condensation of N-benzylated phenyl p-aminobenzoates in the presence of LiHMDS to yield three-membered cyclic aramides that adopt a triangular shape. An ortho-alkyloxy side chain on the N-benzyl protecting group is necessary for the macrocyclization to occur. Linear polymers are formed exclusively in the absence of this Li-chelating group. A model that explains the lack of formation of other cyclic congeners and the demand for an N-(o-alkoxybenzyl) protecting group is providedon the basis of DFT calculations.High-resolution AFM imaging of the prepared molecular triangles on a calcite(10.4) surface shows individual …
A unique microstructure of the fiber networks deposited from foam-fiber suspensions
2015
Abstract Fiber networks can be formed using aqueous foam as the suspending medium. The mean bubble size of the foam affects the resulting pore-size distribution of the fiber network. The foam–fiber interactions cause in particular an increase in the proportion of large micropores of the network, in comparison with the fiber networks that result from traditional water forming at a similar material density. Experiments were carried out for two different types of cellulose fiber, and characterization of the resulting pore structure was based on X-ray microtomography of the resulting fiber networks. The unique pore structure obtained with foam forming was reflected in various macroscopic proper…
Tuning Azoheteroarene Photoswitch Performance through Heteroaryl Design
2017
International audience; Photoswitchable compounds, which can be reversibly switched between two isomers by light, continue to attract significant attention for a wide array of applications. Azoheteroarenes represent a relatively new but understudied type of photoswitch, where one of the aryl rings from the conventional azobenzene class has been replaced with a five-membered heteroaromatic ring. Initial studies have suggested the azoheteroarenes – the arylazopyrazoles in particular – to have excellent photoswitching properties (quantitative switching and long Z isomer half-life). Here we present a systematic computational and experimental study to elucidate the origin of the long thermal hal…
Cobalt Electrolyte/Dye Interactions in Dye-Sensitized Solar Cells: A Combined Computational and Experimental Study
2012
We report a combined experimental and computational investigation to understand the nature of the interactions between cobalt redox mediators and TiO2 surfaces sensitized by :ruthenium and organic dyes, and their impact on. the performance of the corresponding dye-sensitized solar cells (DSSCs). We : focus: on different ruthenium dyes and fully organic dyes, to understand the dramatic loss of efficiency observed for the prototype Ru(II) N719 dye in conjunction with :Cobalt: electrolytes. Both N719- and Z907-based DSSCs showed an increased lifetime in iodine-based electrolyte compared to the cobalt-based redox-shuttle; While the organic D21L6 and D25L6 cycles endowed.With long alkoxy chains,…
Early homogenous amorphous precursor stages of calcium carbonate and subsequent crystal growth in levitated droplets.
2008
An in situ study of the contact-free crystallization of calcium carbonate in acoustic levitated droplets is reported. The levitated droplet technique allows an in situ monitoring of the crystallization while avoiding any foreign phase boundaries that may influence the precipitation process by heterogeneous nucleation. The diffusion-controlled precipitation of CaCO3 at neutral pH starts in the initial step with the homogeneous formation of a stable, nanosized liquid-like amorphous calcium carbonate phase that undergoes in a subsequent step a solution-assisted transformation to calcite. Cryogenic scanning electron microscopy studies indicate that precipitation is not induced at the solution/a…