Alginate/k-Carrageenan Interpenetrated Biopolymeric Aerogels for Nutraceutical Drug Delivery.

Bioactive compounds of natural origin are central to the development of nutraceutical formulations. To improve their stability and to target their delivery to the intestinal or colonic tract, alginate/k-carrageenan spherical gels have been produced at different volumetric ratios (100/0, 70/30, 50/50, 30/70, and 0/100 /), by means of solution dripping and external gelation. Different drying methods were compared, and only through supercritical technologies was it possible to achieve interpenetrated networks that feature nanometric pore size distribution.

Controlling particle size of levan in powder form with different technologies.

Levan is a fructose polysaccharide with multiple applications in different fields, but its obtaining in powdered form with a narrow particle size distribution is a complicated task. Two techniques, electrospraying and supercritical antisolvent (SAS) precipitation, were used to process levan that was first obtained enzymatically. The SAS process was able to micronize the polymer (at experimental conditions far above the mixture critical point of the solvent-antisolvent system) to obtain spherical particles between 0.

Production of Agarose-Hydroxyapatite Composites via Supercritical Gel Drying, for Bone Tissue Engineering.

Bone tissue engineering (BTE) is the most promising strategy to repair bones injuries and defects. It relies on the utilization of a temporary support to host the cells and promote nutrient exchange (i.e.

Supercritical Phase Inversion to Produce Photocatalytic Active PVDF-coHFP_TiO Composites for the Degradation of Sudan Blue II Dye.

TiO-loaded poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-coHFP) membranes were produced by supercritical CO-assisted phase inversion. Three different TiO loadings were tested: 10, 20, and 30 wt% with respect to the polymer. Increasing the TiO amount from 10 wt% to 20 wt% in the starting solution, the transition from leafy-like to leafy-cellular morphology was observed in the section of the membrane.

Validation of a compartmental model to predict drug release from porous structures produced by ScCO techniques.

A global release model is proposed to study the drug release from porous materials for pharmaceutical applications. This model is defined by implementing a compartmental model where the release profile could be explained as the combination of mass transfer phenomena through three compartments as well as a desorption process or dissolution process from the support. This model was validated with five different systems produced with supercritical CO (aerogels, membranes, and fibers), showing different release processes.

Production of Porous Agarose-Based Structures: Freeze-Drying vs. Supercritical CO Drying.

In this work, the effect of two processes, i.e., freeze-drying and supercritical CO (SC-CO) drying, on the final morphology of agarose-based porous structures, was investigated.

PVDF HFP_RuO Nanocomposite Aerogels Produced by Supercritical Drying for Electrochemical Oxidation of Model Tannery Wastewaters.

A supercritical CO drying process was used to prepare an innovative nanocomposite, formed by a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF HFP) aerogel loaded with RuO nanoparticles. The produced nanocomposites, at 10% and 60% w/w of RuO, were tested for the electrochemical oxidation of model tannery wastewaters. The effect of the electrochemical oxidation parameters, like pH, temperature, and current density, on tannic acid, intermediates, and chemical oxygen demand (COD) removal, was investigated.

Microbial Exopolysaccharides as Drug Carriers.

Microbial exopolysaccharides are peculiar polymers that are produced by living organisms and protect them against environmental factors. These polymers are industrially recovered from the medium culture after performing a fermentative process. These materials are biocompatible and biodegradable, possessing specific and beneficial properties for biomedical drug delivery systems.

Supercritical carbon dioxide techniques for processing microbial exopolysaccharides used in biomedical applications.

Microbial exopolysaccharides are polymers that show a great potential for biomedical applications, such as tissue engineering applications and drug delivery, due to their biocompatibility, biodegradability and their gelling properties. These polysaccharides are obtained from a microorganism culture with a relatively straightforward downstream process thanks to their extracellular character, and can be processed to obtain aerogels, fibers and micro- or nano-particles with conventional techniques. However, these techniques present several disadvantages in that they involve time-consuming processes and the use of toxic solvents.

Supercritical Phase Inversion: A Powerful Tool for Generating Cellulose Acetate-AgNO Antimicrobial Membranes.

Antimicrobial composite membranes, formed by cellulose acetate loaded with AgNO particles, were produced by supercritical phase inversion. Different cellulose acetate concentrations were tested (15%, 20%, 30%(/)), whereas the active agent (i.e.

Role of rheological properties on physical chitosan aerogels obtained by supercritical drying.

Chitosan aerogels were obtained after using supercritical carbon dioxide to dry physical hydrogels, studying the effect of the rheological behavior of hydrogels and solutions on the final aerogels properties. An increase on the solutions pseudoplasticity increased the subsequent hydrogels physical entanglement, without showing a significant effect on aerogels morphology (nanoporous) and textural properties (pores of about 10 nm). However, an increase of hydrogel physical entanglement promoted the formation of aerogels with a higher compressive strength (from 0.

Cellulose Acetate and Supercritical Carbon Dioxide: Membranes, Nanoparticles, Microparticles and Nanostructured Filaments.

Cellulose acetate (CA) is a very versatile biocompatible polymer used in various industrial sectors. Therefore, depending on the application, different morphologies are required. Different processes at industrial scale are commonly employed to obtain CA micro or nanoparticles (discontinuous structures) or CA membranes (continuous structures with discontinuities).

Supercritical Fluid Processing of Polymers.

The use of supercritical fluids instead of organic solvents has attracted the interest of numerous researchers, due to the unique peculiarities of supercritical fluids which are characterized by solvent powers comparable to those of liquid organic solvents, diffusivity comparable to those of gaseous substances and quasi-zero surface tension [...

A Phenomenological Approach to Study Mechanical Properties of Polymeric Porous Structures Processed Using Supercritical CO₂.

This work proposes a modeling of the mechanical properties of porous polymers processed by scCO₂, using a phenomenological approach. Tensile and compression tests of alginate/gelatin and cellulose acetate/graphene oxide were modeled using three hyperelastic equations, derived from strain energy functions. The proposed hyperelastic equations provide a fair good fit for mechanical behavior of the nanofibrous system alginate/gelatin (deviations lower than 10%); whereas, due to the presence of the solid in the polymer network, a four-parameter model must be used to fit the composite cellulose acetate/graphene oxide behavior.

Supercritical Assisted Electrospray: An Improved Micronization Process.

A new process is proposed that can largely improve classical electrospray (ESPR) atomization, thanks to the addition of supercritical CO₂ (SC-CO₂) to the liquid mixture, in which a polymer is dissolved, forming an expanded liquid. The consequent reduction of surface tension and viscosity allows the production of micrometric or nanometric particles of controlled size and distribution at a production rate up to one hundred times that of the traditional process. The new process was applied to particle generation from a very high molecular weight polyvinylpyrrolidone (PVP) and tested at different polymer percentages by weight and at different pressures.

SC-CO-assisted process for a high energy density aerogel supercapacitor: the effect of GO loading.

Energy density, safety, and simple and environmentally friendly preparation methods are very significant aspects in the realization of a compact supercapacitor. Herein we report the use of a supercritical CO-assisted gel drying process (SC-CO) for the preparation of porous electrodes containing dispersed graphene in a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) binder membrane to sandwich in a new portable supercapacitor based on graphene oxide (GO). A GO loading of 60 wt.

Interpenetration of Natural Polymer Aerogels by Supercritical Drying.

Natural polymers, such as alginate and gelatin, can be used to produce scaffolds for tissue engineering applications; but, their mechanical and biochemical performance should be improved. A possible solution to obtain this result, is the generation of multi-component scaffolds, by blending two or more polymers. One way to realize it, is the formation of an interpenetrating polymer network (IPN).

Regeneration techniques for bone-to-tendon and muscle-to-tendon interfaces reconstruction.

Introduction: The complex structure of the bone-tendon and muscle-tendon junctions makes their reproduction for tissue engineering applications very difficult. Relatively few studies have investigated the characteristics of these regions from a tissue engineering view point.

Sources Of Data: PubMed, Thomson Reuters, Scopus and Google Scholar databases were searched using various combinations of the keywords 'Tendon', 'Myotendinous junction', 'Osteotendinous junction', 'Tissue engineering' and 'Scaffold'.

Supercritical fluid assisted process for the generation of cellulose acetate loaded structures, potentially useful for tissue engineering applications.

Supercritical CO2 phase inversion offers an alternative to obtain solvent free structures with short processing times and preservation of the morphology. We prepared cellulose acetate structures loaded with drug (ibuprofen) to perform experiments at pressures and temperatures ranging between 150 and 250 bars and 35 and 55 °C. The structures were properly characterized by SEM, EDX and DSC; drug controlled release experiments were also performed.

Biodegradable synthetic scaffolds for tendon regeneration.

Tissue regeneration is aimed at producing biological or synthetic scaffolds to be implanted in the body for regenerate functional tissues. Several techniques and materials have been used to obtain biodegradable synthetic scaffolds, on which adhesion, growth, migration and differentiation of human cells has been attempted. Scaffolds for tendon regeneration have been less frequently proposed, because they have a complex hierarchical structure and it is very difficult to mimic their peculiar mechanical properties.

Tubular perfusion system culture of human mesenchymal stem cells on poly-L-lactic acid scaffolds produced using a supercritical carbon dioxide-assisted process.

In vitro human mesenchymal stem cell (hMSC) proliferation and differentiation is dependent on scaffold design parameters and specific culture conditions. In this study, we investigate how scaffold microstructure influences hMSC behavior in a perfusion bioreactor system. Poly-L-lactic acid (PLLA) scaffolds are fabricated using supercritical carbon dioxide (SC-CO(2)) gel drying.