Search results for "HeLa"
showing 10 items of 738 documents
Synthesis and Characterization of Stimuli-Responsive Star-Like Polypept(o)ides: Introducing Biodegradable PeptoStars
2017
tar-like polymers are one of the smallest systems in the class of core crosslinked polymeric nanoparticles. This article reports on a versatile, straightforward synthesis of three-arm star-like polypept(o)ide (polysarcosine-block-polylysine) polymers, which are designed to be either stable or degradable at elevated levels of glutathione. Polypept(o)ides are a recently introduced class of polymers combining the stealth-like properties of the polypeptoid polysarcosine with the functionality of polypeptides, thus enabling the synthesis of materials completely based on endogenous amino acids. The star-like homo and block copolymers are synthesized by living nucleophilic ring opening polymerizat…
Dinuclear alkoxo-bridged copper(II) coordination polymers: Syntheses, structural and magnetic properties
2010
Abstract The alkoxo-bridged dinuclear copper(II) complexes [Cu2(ap)2(NO2)2] (1), [Cu2(ap)2(C6H5COO)2] (2) and [Cu2(ap)2μ-1,3-C6H4(COO)2(dmso)2]·dmso (3) (ap = 3-aminopropanolato and dmso = dimethyl sulfoxide) have been synthesized via self-assembly from copper(II) perchlorate, 3-aminopropanol as main chelating ligand and nitrite and isophthalate anions as spacers and benzoate anion as auxiliary ligand. Complexes 1 and 3 crystallize as 2D and 1D coordination polymers, respectively, and their structures consist of dinuclear [Cu2(ap)2]2+ units connected with nitrite and isophthalate ligands. The adjacent dinuclear units of 2 and 1D polymers of 3 are further connected by hydrogen bonds resultin…
4-Nitrophenyl phosphoric acid and its four different potassium salts: a solid state structure and kinetic study
2006
The structures of 4-nitrophenyl phosphoric acid, H2NPP (1), and its four different potassium salts, K(H2NPP)(HNPP) (2), K(HNPP)·CH3OH (3), K(HNPP)·2H2O (4), and K2(NPP)·4H2O (5), were determined by X-ray diffraction methods. These investigations, together with the study of the role of potassium ions in the hydrolysis of 4-nitrophenyl phosphate, provided information about interactions between the acid, monoanionic and dianionic forms of 4-nitrophenyl phosphate and the potassium cations. In the crystalline state, the H2NPP molecules form one-dimensional chains of bifurcated O–H⋯O hydrogen bonds between phosphate groups. A different network, derived from ladder-like chains of the O–H⋯O hydroge…
Rapid inactivation and proteasome-mediated degradation of OGG1 contribute to the synergistic effect of hyperthermia on genotoxic treatments
2013
Inhibition of DNA repair has been proposed as a mechanism underlying heat-induced sensitization of tumour cells to some anticancer treatments. Base excision repair (BER) constitutes the main pathway for the repair of DNA lesions induced by oxidizing or alkylating agents. Here, we report that mild hyperthermia, without toxic consequences per se, affects cellular DNA glycosylase activities, thus impairing BER. Exposure of cells to mild hyperthermia leads to a rapid and selective inactivation of OGG1 (8-oxoguanine DNA glycosylase) associated with the relocalisation of the protein into a detergent-resistant cellular fraction. Following its inactivation, OGG1 is ubiquitinated and directed to pro…
Gated mesoporous silica nanoparticles for the controlled delivery of drugs in cancer cells
2015
In recent years, mesoporous silica nanoparticles (MSNs) have been used as effective supports for the development of controlled-release nanodevices that are able to act as multifunctional delivery platforms for the encapsulation of therapeutic agents, enhancing their bioavailability and overcoming common issues such as poor water solubility and poor stability of some drugs. In particular, redox-responsive delivery systems have attracted the attention of scientists because of the intracellular reductive environment related to a high concentration of glutathione (GSH). In this context, we describe herein the development of a GSH-responsive delivery system based on poly(ethylene glycol)- (PEG-)…
Enzyme-responsive silica mesoporous supports capped with azopyridinium salts for controlled delivery applications
2012
11 páginas, 7 figuras, 3 tablas y 2 esquemas
Cathepsin-B Induced Controlled Release from Peptide-Capped Mesoporous Silica Nanoparticles
2014
New capped silica mesoporous nanoparticles for intracellular controlled cargo release within cathepsin B expressing cells are described. Nanometric mesoporous MCM-41 supports loaded with safranin O (S1-P) or doxorubicin (S2-P) containing a molecular gate based on a cathepsin B target peptidic sequence were synthesized. Solids were designed to show "zero delivery" and to display cargo release in the presence of cathepsin B enzyme, which selectively hydrolyzed in vitro the capping peptide sequence. Controlled delivery in HeLa, MEFs WT, and MEFs lacking cathepsin B cell lines were also tested. Release of safranin O and doxorubicin in these cells took place when cathepsin B was active or presen…
Amidase-responsive controlled release of antitumoral drug into intracellular media using gluconamide-capped mesoporous silica nanoparticles
2012
MCM-41 silica nanoparticles were used as inorganic scaffolding to prepare a nanoscopic-capped hybrid material S1, which was able to release an entrapped cargo in the presence of certain enzymes, whereas in the absence of enzymes, a zero release system was obtained. S1 was prepared by loading nanoparticles with Safranine O dye and was then capped with a gluconamide derivative. In the absence of enzymes, the release of the dye from the aqueous suspensions of S1 was inhibited as a result of the steric hindrance imposed by the bulky gluconamide derivative, the polymerized gluconamide layer and the formation of a dense hydrogen-bonded network around the pore outlets. Upon the addition of amidase…
Enzyme-Responsive Intracellular Controlled Release Using Nanometric Silica Mesoporous Supports Capped with "Saccharides"
2010
The synthesis of new capped silica mesoporous nanoparticles for on-command delivery applications is described. The gate-like functional hybrid systems consisted of nanoscopic MCM-41-based materials functionalized on the pore outlets with different “saccharide” derivatives and a dye contained in the mesopores. A series of hydrolyzed starch products as saccharides were selected. The mesoporous silica nanoparticles S1, S2, and S3 containing the grafted starch derivatives Glucidex 47, Gludicex 39, and Glucidex 29 were synthesized. Additionally, for comparative purposes solid S4 containing lactose was prepared. Delivery studies in pure water in the presence of pancreatin or -D-galactosidase were…
Influence of ligand density on the properties of metal-chelate affinity supports.
1993
A new procedure has been developed to immobilize iminodiacetic acid (IDA) onto the surface of silica supports, such as LiChrospher Si-1000 and 1.5-microns nonporous silica, for use in high-performance immobilized metal affinity chromatography (HPIMAC) of proteins. This IDA immobilization method has been achieved through the synthesis of a new silylation reagent, 1-(iminodiacetic acid di-tert-butylester)-3-glycidoxy-propyltrimethoxysilane (IDA-silane). Various modified silicas of different ligand densities have been prepared by using mixtures between 1 and 100% of the IDA-silane diluted with the corresponding 3-glycidoxy-propyltrimethoxysilane (GLYMO-silane). Frontal analysis was used with t…