Search results for "controlled release."
showing 10 items of 132 documents
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…
Enzyme-Mediated Controlled Release Systems by Anchoring Peptide Sequences on Mesoporous Silica Supports
2011
[EN] Gated community: Peptides anchored to the surface of silica mesoporous supports by a valid procedure act as gatekeepers. In this way, "zero release" supports that selectively deliver the cargo in the presence of a suitable peptidase are obtained (see picture, red spheres: cargo, colored chains: peptides). © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Stability of different mesoporous silica particles during an in vitro digestion
2016
Mesoporous silica materials have the ability to entrap drugs, nutrients and functional biomolecules and can be able to act as smart delivery systems capable to control and target the release of their cargo in a particular part of the gastrointestinal tract when administrated orally. However, the aptness of these encapsulation supports in in vivo oral controlled release relies on their chemical stability through the digestive tube. In this context, we have evaluated the stability of four different mesoporous silica particles, frequently used as encapsulating supports, during an in vitro digestion process comprising buccal, stomach and intestinal phases. Results showed that after 4 h of diges…
In Situ Perfusion Model in Rat Colon for Drug Absorption Studies: Comparison with Small Intestine and Caco-2 Cell Model.
2015
Our aim is to develop and to validate the in situ closed loop perfusion method in rat colon and to compare with small intestine and Caco-2 cell models. Correlations with human oral fraction absorbed (Fa) and human colon fraction absorbed (Fa_colon) were developed to check the applicability of the rat colon model for controlled release (CR) drug screening. Sixteen model drugs were selected and their permeabilities assessed in rat small intestine and colon, and in Caco-2 monolayers. Correlations between colon/intestine/Caco-2 permeabilities versus human Fa and human Fa_colon have been explored to check model predictability and to apply a BCS approach in order to propose a cut off value for CR…
Boosting the in situ encapsulation of proteins with MIL-100(Fe): the role of strong Lewis acid centers
2021
Encapsulation of biomolecules using Metal-Organic Frameworks (MOFs) to form stable biocomposites has been demonstrated a valuable strategy for their preservation and controlled release, which has been however restricted to specific electrostatic surface conditions. We present a general in situ strategy that promotes the spontaneous MOF growth onto a broad variety of proteins, for the first time, regardless of their surface nature. We demonstrate that MOFs based on cations exhibiting considerable inherent acidity such as MIL-100(Fe) enable biomolecule encapsulation, including alkaline proteins previously inaccesible by the welldeveloped in situ encapsulation with azolate-based MOFs. In parti…
Defining level A IVIVC dissolution specifications based on individual in vitro dissolution profiles of a controlled release formulation.
2018
Regulatory guidelines recommend that, when a level A IVIVC is established, dissolution specification should be established using averaged data and the maximum difference between AUC and Cmax between the reference and test formulations cannot be greater than 20%. However, averaging data assumes a loss of information and may reflect a bias in the results. The objective of the current work is to present a new approach to establish dissolution specifications using a new methodology (individual approach) instead of average data (classical approach). Different scenarios were established based on the relationship between in vitro-in vivo dissolution rate coefficient using a level A IVIVC of a cont…
Self-Immolative Linkers as Caps for the Design of Gated Silica Mesoporous Supports
2016
A new hybrid material based on sulforhodamine-B dye-loaded silica mesoporous nanoparticles capped with a self-immolative gate has been synthesized and characterized. The gated material's controlled release behavior is monitored under different pH conditions. Under acidic and neutral conditions, a low level of dye release is detected. However, at slightly basic pH, significant dye release occurs owing to deprotonation of the phenol moiety in the capping molecule, which results in its disassembly.
Ion-exchange fibers and drugs: a transient study.
2003
The objective of this study was to theoretically model and experimentally measure the kinetics and extent of drug release from different ion-exchange materials using an in-house-designed flow-cell. Ion-exchange fibers (staple fibers and fiber cloth) were compared with commercially available ion-exchange materials (resins and gels). The functional ion-exchange groups in all the materials were weak -COOH or strong -SO3H groups. The rate and extent of drug release from the fibers (staple fiber>fiber cloth) was much higher than that from the resin or the gel. An increase in the hydrophilicity of the model drugs resulted in markedly higher rates of drug release from the fibers (nadolol>metoprolo…
Chitosomes loaded with cranberry proanthocyanidins attenuate the bacterial lipopolysaccharide-induced expression of iNOS and COX-2 in raw 264.7 macro…
2009
Chitosan binds to negatively charged soy lecithin liposomes by an electrostatic interaction driven by its positively charged amino group. This interaction allows stable covered vesicles (chitosomes) to be developed as a suitable targeted carrier and controlled release system. This study investigated the effect of chitosomes on the activation of cranberry proanthocyanidins (PAC) in Raw 264.7 macrophages. Chitosomes were characterized according to size, zeta potential, PAC-loading, and release properties. Results showed an increase in the net positive charge and size of the liposomes as the concentration of chitosan was increased, suggesting an effective covering of the vesicles by means of e…
Stimuli-Responsive Polymeric Nanocarriers for Drug Delivery, Imaging, and Theragnosis.
2020
In the past few decades, polymeric nanocarriers have been recognized as promising tools and have gained attention from researchers for their potential to efficiently deliver bioactive compounds, including drugs, proteins, genes, nucleic acids, etc., in pharmaceutical and biomedical applications. Remarkably, these polymeric nanocarriers could be further modified as stimuli-responsive systems based on the mechanism of triggered release, i.e., response to a specific stimulus, either endogenous (pH, enzymes, temperature, redox values, hypoxia, glucose levels) or exogenous (light, magnetism, ultrasound, electrical pulses) for the effective biodistribution and controlled release of drugs or genes…