Implantable
long-acting delivery systems able to minimize off-target
side effects and locally provide non-invasive imaging reporting are
of utmost importance to offer a precise treatment of internal diseases
and accurate assessment of disease progression, such as in local infections
and tumor relapse following surgery, among other diseases. Here, a
biocompatible xanthan gum/Fe3O4-based drug-loaded
magnetic nanoparticle composite hydrogel with suitable rheological
properties and theranostic performance was designed. The ultra-high
efficacy of the chemically modified polysaccharide matrix to simultaneously
encapsulate hydrophilic drugs and magnetic iron oxide nanoparticles
rendered the final hydrogel magnetically responsive to enable thermally
induced controlled drug delivery by magnetic hyperthermia as well
as non-invasive monitoring by magnetic resonance imaging (MRI). In
addition to an enhanced activity of the drug-loaded hydrogel compared
to the free drug, results showed that the application of an alternating
magnetic field efficiently stimulated a 3-fold faster release of the
encapsulated drug compared to passive conditions, whereas a concentration-dependent
shortening of the water protons’ relaxation time at a clinical
field of 3 T confirmed this magnetic hydrogel as a T
2-MRI contrast enhancer. Altogether, these properties
open a novel dimension for the application of these versatile magnetic
nanoparticle composite hydrogels, from traditional topical uses to
more internal surgery interventions in dentistry, oncology, or wound
healing of critical skin damage and infections.
This paper addressed the application of deacetylated xanthan (XGDS) and chitosan (CTS) as a mixture blend forming hydrophilic matrices for Tramadol (TD) sustained release tablets. XGDSs derivatives were obtained by alkaline treatment of xanthan gum (XG) with various degrees of deacetylation (DD). The obtained products were characterized in terms of structural, thermal and physicochemical properties. Different tablet formulations containing CTS/XGDSs were prepared by direct compression method and compared to CTS/XG tablets. Flow properties of powder mixtures and pharmaceutical characteristics were evaluated. The dissolution test of TD was realized under simulated gastric and intestinal conditions to achieve drug release more than 24 h. All developed tablets were found conforming to standard evaluation tests. It was shown that CTS/XGDSs matrices ensure a slower release of TD in comparison with CTS/XG based formulations. Meanwhile, increasing DD resulted in a decrease of drug release. In addition, TD release from XGDS matrices was faster at pH (6.8) than at acidic pH (1.2). The matrix tablets based on CTS/XGDS4 (DD = 98.08%) were selected as the best candidates compared to the other systems in prolonging drug release. The optimal formulation was found to release 99.99% of TD after 24 h following a non-Fickian type.
Blends of polypropylene (PP3) and polystyrene (PS) were studied and, their rheological behavior was determined and discussed in detail. The interfacial tension between the blend components was evaluated from the rheological data and the storage modulus by using two well-known models: Palierne model and Choi-Schowalter equation. The theoretical predictions were compared with experimental data obtained from PP3/PS blends. The obtained results showed that the Palierne model could predict the rheological and viscoelastic properties of the considered polymer blends. In addition, the interfacial tensions between PP3 and PS were evaluated and compared with those cited in the literature. It was also found that the Palierne model was more accurate than Choi-Schowalter one in determining the interfacial tension.
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