Search results for "Gels"
showing 10 items of 671 documents
Systematic Modulation of the Supramolecular Gelation Properties of Bile Acid Alkyl Amides
2018
The self-assembly properties of nine low-molecular-weight gelators (LMWGs) based on bile acid alkyl amides were studied in detail. Based on the results, the number of hydroxyl groups attached to the steroidal backbone plays a major role in the gelation, although the nature of the aliphatic side chain also modulates the gelation abilities. Of the 50 gel systems studied, 35 are based on lithocholic acid and 15 on cholic acid derivatives. The deoxycholic acid derivatives did not form any gels. The gelation occurred primarily in aromatic solvents and the gels manifested typical fibrous or spherical morphologies. The 13C cross-polarized magic angle spinning (CPMAS) NMR spectra measured on the cr…
Bile acid amidoalcohols: simple organogelators.
2003
Simple bile acid amide synthesis of lithocholic and deoxycholic acids with 2-aminoethanol and 3-aminopropanol are reported. The structural properties of these amides were examined by NMR spectroscopic, ESI-TOF mass spectral, and X-ray crystallographic methods. The gelation properties of these amides in common organic solvents and in three different water solutions were also investigated using Tyndall effect, SEM, TEM, and optical microscopy. 2-Hydroxyethylamides were found to be effective gelators in chlorinated organic solvents and 3-hydroxypropylamides in aromatic solvents. Both derivatives thicken neutral and acidic water solutions.
Bile acid alkylamide derivatives as low molecular weight organogelators: systematic gelation studies and qualitative structural analysis of the syste…
2011
A series of amino- and hydroxyalkyl amides of bile acids have been synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), (1)H and (13)C nuclear magnetic resonance spectroscopy (NMR), as well as electrospray ionization mass spectrometry (ESI-MS) measurements. The ability of the synthesized molecules to promote gel formation was systematically investigated. Out of 396 combinations formed by 11 compounds and 36 different solvents, 22 gel-containing systems were obtained with 1% (w/v) gelator concentration. Apart from one exception, the gelator compounds were lithocholic acid derivatives. This challenges the general trend of bile acid-based physical gelators, accordin…
In Vivo Gene-Silencing in Fibrotic Liver by siRNA-Loaded Cationic Nanohydrogel Particles
2015
Cationic nanohydrogel particles loaded with anti-Col1α1 siRNA suppress collagen synthesis and deposition in fibrotic mice: Systemically administered 40 nm sized nanogel particles accumulate in collagen-expressing cells in the liver. Their siRNA payload induces a sequence specific in vivo gene knockdown affording an efficient antifibrotic effect in mice with liver fibrosis.
Cationic Nanohydrogel Particles for Therapeutic Oligonucleotide Delivery.
2017
Short pharmaceutical active oligonucleotides such as small interfering RNA (siRNA) or cytidine-phosphate-guanosine (CpG) are considered as powerful therapeutic alternatives, especially to medicate hard-to-treat diseases (e.g., liver fibrosis or cancer). Unfortunately, these molecules are equipped with poor pharmacokinetic properties that prevent them from translation. Well-defined nanosized carriers can provide opportunities to optimize their delivery and guide them to their site of action. Among several concepts, this Feature Article focuses on cationic nanohydrogel particles as a universal delivery system for small anionic molecules including siRNA and CpG. Cationic nanohydrogels are deri…
Guar gum/borax hydrogel: Rheological, low field NMR and release characterizations
2013
Guar gum (GG) and Guar gum/borax (GGb) hydrogels are studied by means of rheology, Low Field Nuclear Magnetic Resonance (LF NMR) and model drug release tests. These three approaches are used to estimate the mesh size (ζ) of the polymeric network. A comparison with similar Scleroglucan systems is carried out. In the case of GGb, the rheological and Low Field NMR estimations of ζ lead to comparable results, while the drug release approach seems to underestimate ζ. Such discrepancy is attributed to the viscous effect of some polymeric chains that, although bound to the network to one end, can freely fluctuate among meshes. The viscous drag exerted by these chains slows down drug…
Luminescent supramolecular heterometallic macrocycles and their encapsulation on cholate gels
2018
The metal complex formed by coordination of Zn(II) to 1,7-bis(4-methylpyridine)-4-(2- naphthylmethyl)-1,4,7-triazaheptane (ZnL2+) was reacted in aqueous solution with [Pd(NO3)2(en)] and [Pt(NO3)2(en)] salts to form the self-assembled heterometallic macrocycles [Zn2L2Pd2(en)2]8+ and [Zn2L2Pt2(en)2]8+, respectively. Pd(II) and Pt(II)- coordination modulates the original emission of ZnL2+ arising from the presence of the naphthalene chromophore and the formation of the macrocycles can be monitored due to the PET process occurring with coordination of Pd(II) and Pt(II) to the pyridine units of ZnL2+. Additionally, several studies reveal that these heteromacrocycles can be encapsulated in Zn(II)…
3D printing novel in vitro cancer cell culture model systems for lung cancer stem cell study
2021
Two-dimensional (2D) in vitro cell cultures and laboratory animals have been used traditionally as the gold-standard preclinical cancer model systems. However, for cancer stem cell (CSC) studies, they exhibit notable limitations on simulating native environment, which depreciate their translatability for clinical development purposes. In this study, different three-dimensional (3D) printing platforms were used to establish novel 3D cell cultures enriched in CSCs from non-small cell lung cancer (NSCLC) patients and cell lines. Rigid scaffolds with an elevated compressive modulus and uniform pores and channels were produced using different filaments. Hydrogel-based scaffolds were printed with…
Design, synthesis and stimuli responsive gelation of novel stigmasterol-amino acid conjugates.
2020
Abstract An efficient synthesis of three novel stigmasterol-amino acid (glycine, l -leucine and l -phenylalanine) conjugates as stimuli responsive gelators is reported. The gelation properties of the prepared compounds were investigated in a variety of organic as well as aqueous solvents. The most striking finding of our investigation was that the hydrochloride salts of the prepared conjugates acted as gelators, whereas the neutral conjugates were either non-gelators or formed only a weak gel in anisole. The hydrochloride salts of stigmasteryl glycinate and l -leucinate form gels in n-alcohols (n = 4–10) and in ethane-1,2-diol, and that of stigmasteryl l -phenylalaninate forms gels in aroma…
DIFFERENTIAL SCANNING CALORIMETRY STUDY ON DRUG RELEASE FROM AN INULIN-BASED HYDROGEL AND ITS INTERACTION WITH A BIOMEMBRANE MODEL:pH AND LOADING EFF…
2008
Inulin has been derivatized with methacrylic anhydride (MA) and succinic anhydride (SA) to obtain a methacrylated/succinilated derivative (INU-MA-SA) able to produce a pH sensitive hydrogel after UV irradiation. The hydrogel was characterized and loaded with diflunisal (10.4, 17 and 24%, w/w) chosen as a model drug. The drug release from INU-MA-SA-based hydrogel to a biomembrane model made by unilamellar vesicles of dimyristoylphosphatidyl-choline (DMPC) was investigated at pH 4.0 and 7.4 by differential scanning calorimetry (DSC) that appears to be a suitable technique to follow the transfer kinetics of a drug from a controlled release system to a biomembrane model. The drug release from t…