Ketoprofen poly(lactide-co-glycolide) physical interaction studied by Brillouin spectroscopy and molecular dynamics simulations.

The performances of poly(lactic-co-glycolic acid) drug delivery systems are affected by the molecular interactions established between the drug and the polymer matrix as well as by the physical state of the drug embedded. Indeed, the drug may induce polymer plasticization with a drastic change in the release kinetics and medicinal product performances. The aim of this study was to better understand the interactions between poly(lactic-co-glycolic acid) and ketoprofen, the latter known to plasticize hydrophilic and hydrophobic polymers. Ketoprofen interacts with poly(lactic-co-glycolic acid) exerting a maximum plasticizing effect at weight fractions around 0.25. Higher ketoprofen amounts form heterogeneous mixtures with the non-soluble molecules dispersed in the matrix as crystals or amorphous domains, depending on the preparation method. Unexpectedly, the amorphous ketoprofen dispersed in the poly(lactic-co-glycolic acid) matrix is remarkably stable. H-bonding seems responsible for the glass transition temperature reduction and the limited solubility. Brillouin spectroscopy and molecular dynamics simulation data suggest that ketoprofen solubility increases with temperature and non-polar interactions are responsible for this phenomenon.

Effect of the Nano-Ca(OH)2 Addition on the Portland Clinker Cooking Efficiency.

A new technology was tested to improve the cooking efficiency of the raw mixture for Portland clinker production by the use of nano-Ca(OH)2. A decrease in the free lime concentration after the firing of approximately 35% and 55% in the nano-added clinkers burned at 1350 °C and 1450 °C, respectively, with respect to the standard Portland clinkers was observed. Moreover, in the nano-added clinkers, a slight decrease in alite (C3S), of approximately 2-4 wt%, and increase in belite (C2S), of approximately 5-6 wt%, were observed. Despite these variations, the C2S and C3S abundance lies within the ranges for standard Portland clinkers. The results showed that the nano-addition leads to an increase of the raw mixtures' cooking efficiency. The relatively low energy required for the clinker firing could be used to increase the plant productivity and decrease the CO2 emissions during clinker burning. The decrease of the work index of the clinkers produced by the use of the nano-Ca(OH)2 also contributes to the energy saving during clinker grinding. Differences were also found in the pore size distribution among nano-added clinkers and the standard Portland clinker. The smallest porosities with the modal volume lying in the class of 3∙10-6 mm3 were found to increase by the use of nano-Ca(OH)2. However, the pore volumes higher than 2.0∙10-5 mm3 decreased in the nano-added clinkers.

Biodegradable composite porous poly(dl-lactide-co-glycolide) scaffold supports mesenchymal stem cell differentiation and calcium phosphate deposition.

In recent decades, tissue engineering strategies have been proposed for the treatment of musculoskeletal diseases and bone fractures to overcome the limitations of the traditional surgical approaches based on allografts and autografts. In this work we report the development of a composite porous poly(dl-lactide-co-glycolide) scaffold suitable for bone regeneration. Scaffolds were produced by thermal sintering of porous microparticles. Next, in order to improve cell adhesion to the scaffold and subsequent proliferation, the scaffolds were coated with the osteoconductive biopolymers chitosan and sodium alginate, in a process that exploited electrostatic interactions between the positively charged biopolymers and the negatively charged PLGA scaffold. The resulting scaffolds were characterized in terms of porosity, degradation rate, mechanical properties, biocompatibility and suitability for bone regeneration. They were found to have an overall porosity of ∼85% and a degradation half time of ∼2 weeks, considered suitable to support de novo bone matrix deposition from mesenchymal stem cells. Histology confirmed the ability of the scaffold to sustain adipose-derived mesenchymal stem cell adhesion, infiltration, proliferation and osteo-differentiation. Histological staining of calcium and microanalysis confirmed the presence of calcium phosphate in the scaffold sections.

Montmorillonite-chitosan-chlorhexidine composite films with antibiofilm activity and improved cytotoxicity for wound dressing.

HYPOTHESIS: Chlorhexidine (CLX) is a good antimicrobial agent, but its use in treatment of wounds is limited because of its cytotoxicity towards human fibroblasts. A delivery system, able to release CLX in a localized and prolonged manner, could guarantee antimicrobial activity with reduced cytotoxic. Thus in this work the preparation and characterization of chitosan/montmorillonite composite films containing CLX, able to offer a prolonged CLX release, is described. The antimicrobial and antibiofilm activities and cytotoxicity of films were investigated. EXPERIMENTAL: CLX was intercalated between the layers of montmorillonite (MONT-Na), and the intercalated product (MONT-CLX) was characterized by X-ray powder diffraction (XRPD), thermogravimetric analysis (TGA) and FT-IR spectroscopy. Then chitosan/MONT-CLX films were prepared and characterized. For comparison, films loaded with neat CLX and MONT-Na/CLX were prepared. All prepared films were tested for their antimicrobial and antibiofilm activities. Cytotoxicity towards human skin keratinocytes and human fibroblasts HuDe was evaluated as well. FINDINGS: All prepared films showed good antimicrobial and antibiofilm activities. As concerns cytotoxicity the film containing MONT-CLX at 1% CLX concentration resulted no cytotoxic. These results confirm the potential use of chitosan films containing MONT-CLX as a potential wound dressing material to prevent microbial colonization in wounds.