PGSS micronized PEG 1500 with unconventional fluids (SF6).
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Melting points of PEG under pressure of propane and SF6 were determined.Gas solubility along the melting curve of PEG ...under pressure of argon and CO2 was measured.PGSS micronization of PEG 1500 with unconventional fluids was successfully performed.More uniform particles were obtained by unconventional fluids and at lower pressures.
Melting points of polyethylene glycols (PEGs) with molar masses (1500, 4000, 10000 and 35000)g/mol under pressure of propane and sulfur hexafluoride have been determined and were compared with previous published data with CO2 and argon. Additionally, solubilities of argon and CO2 in PEGs have been determined along the melting curve. The desorption of gases from PEG to constant mass at atmospheric conditions was followed for propane, CO2, argon and SF6⿿previously the system was exposed to conditions 343K and 15MPa. Finally, PGSS micronization of PEG with molar mass 1500g/mol with fluids propane, CO2, argon and SF6 was successfully performed at two operating conditions: at the minimal melting point of PEG under fluid and at 328K and 15MPa. This is the first report of PEG micronization with unconventional fluids: propane, SF6 and argon.
β-carotene is one of the most common pigments in nature. β-carotene formulations provide protection against oxidation and degradation processes. They are very attractive as natural colorants because ...they add value to the product due to their antioxidant and pro-vitamin activities. This work presents a study of the formulation of β-carotene with poly-(ε-caprolactone) by Particles from Gas Saturated Solutions (PGSS) process. Particle sizes in the range of 270–650μm with a β-carotene content of up to 340ppm were obtained using polycaprolactone with a molecular weight of 10000gmol−1, while using a polycaprolactone with a molecular weight of 4000gmol−1 the particle size was reduced to 110–130μm. The influence of several process parameters on particle size and β-carotene content was studied, including pressure, temperature, time of contact between CO2 and polymer melt for mixture homogenization, and molar ratio β-carotene:polymer.
β-carotene was encapsulated in polycaprolactones precipitated with a particles from gas saturated solutions (PGSS) process. Particle size and morphology depended on the molecular weight of the polymer, which can be due to the lower viscosity and higher CO2 solubility in polymers with a lower molecular weight. Display omitted
► β-carotene was encapsulated in polycaprolactone precipitated by a PGSS process. ► Particles of 100–600μm with β-carotene contents up to 340ppm were obtained. ► Small and regular particles were obtained with a low molecular weight polymer. ► Differences can be related to the viscosity and CO2 solubility in the polymer melt.
The particles from gas saturated solutions (PGSS) process were performed to encapsulate lactofer-rin, an iron-binding milk glycoprotein, using supercritical carbon dioxide (scCO2). A natural en-teric ...polymer, shellac, was used as a coating material of lactoferrin carried out by the PGSS pro-cess. Conditions were optimized by applying different temperatures (20–50 °C) and pressures (8–10 MPa) and the particles were evaluated for particle shape and size, lactoferrin encapsulation ef-ficiency, Fourier transform infrared (FTIR) spectroscopy to confirm lactoferrin entrapment and in vitro dissolution studies at different pH values. Particles with an average diameter of 75.5 ± 7 μm were produced with encapsulation efficiency up to 71 ± 2%. Furthermore, particles that showed high stability in low pH (pH 1.2) and a sustained release over time (t2h = 75%) in higher pH (pH 7.4) suggested an effective encapsulation process for the protection of lactoferrin from gastric di-gestion.
Biopolymers including natural (e.g., polysaccharides, proteins, gums, natural rubbers, bacterial polymers), synthetic (e.g., aliphatic polyesters and polyphosphoester), and biocomposites are of ...paramount interest in regenerative medicine, due to their availability, processability, and low toxicity. Moreover, the structuration of biopolymer-based materials at the nano- and microscale along with their chemical properties are crucial in the engineering of advanced carriers for drug products. Finally, combination products including or based on biopolymers for controlled drug release offer a powerful solution to improve the tissue integration and biological response of these materials. Understanding the drug delivery mechanisms, efficiency, and toxicity of such systems may be useful for regenerative medicine and pharmaceutical technology. The main aim of the Special Issue on “Biopolymers in Drug Delivery and Regenerative Medicine” is to gather recent findings and current advances on biopolymer research for biomedical applications, particularly in regenerative medicine, wound healing, and drug delivery. Contributions to this issue can be as original research or review articles and may cover all aspects of biopolymer research, ranging from the chemical synthesis and characterization of modified biopolymers, their processing in different morphologies and hierarchical structures, as well as their assessment for biomedical uses.
Natural extracts are widely used in groceries, in pharmaceutics and nutraceuticals. For foods these extracts are mainly used for flavoring or coloring the products. For pharmaceuticals and ...nutraceuticals active ingredients like antioxidants are of special interest. Traditionally these extracts are obtained by water or organic solvent extraction. Afterwards the liquid extracts are dried with classical spray drying techniques or freeze drying.
In this work a new process for the gentle drying of natural extracts is presented. The process is based on a high-pressure spray technique called particles from gas saturated solutions (PGSS). The solution to be dried is dosed with a high-pressure pump to a static mixer, where compressed and preheated carbon dioxide is added. Afterwards this mixture is rapidly depressurized from high pressure via a nozzle into a spray tower, operated at ambient pressure—fine droplets are formed. By adjusting the pre-expansion conditions it is possible to evaporate the solvent in spray tower. The solvent can be withdrawn with the expanded carbon dioxide and finally a dry powder of the extract is obtained. Like the most supercritical fluid processes the drying is carried out at low temperature (30–60
°C) and in an inert, oxygen-free atmosphere. This makes the process very promising for sensitive substances. First investigations with this technique were made with green tea extracts, which contain antioxidants polyphenols. Dry and free flowing powders were obtained by the spray process without degradation of the active ingredients.
19F NMR spectra analysis of gas-filled Gelucire 50/13 particles produce at 80°C and 8.5MPa at different ratios carrier to PFC-gas, C4F8.
•Gas-filled microparticles have been produced by Particles ...from Gas Satured Solution process.•Microparticles were formed by a core of a low molecular weight perfluoroalkane and a lipid shell.•Gases, C3F8 or C4F8, were qualitatively determined by 19F NMR spectroscopy.•The effect of the lipid: gas ratio has been studied at fixed operational conditions, 8.5MPa and 80°C.
For the first time, gas-filled microparticles were successfully prepared using a supercritical fluid based technology. Low molecular weight perfluorcarbon (PFC) gases, C3F8 or C4F8, have been encapsulated into Gelucire® 50/13 (lipid-based carrier: polyethylene glycol glycerides), using PGSS® (Particles from Gas Saturated Solution) technique. Particles were produced from the fast expansion of the melted lipid carrier saturated with a mixture of (CO2+PFC). The presence of the gas into the produced microparticles was verified by Nuclear Magnetic Resonance (NMR) analysis of fluorine atom. The effect of carrier to PFC mass ratio and PFC structure on the entrapment efficiency of the PFC gas into the particles was evaluated at fixed at 8.5MPa and 353K. These parameters were fixed in a preliminary study according to the morphology, size and flowability of the particles. The stability of encapsulated C4F8 in microparticles showed to be higher than C3F8; it was determined to be 2h, at room conditions at the optimized carrier: PFC mass ratio of 30:1.
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▶ We investigated the production of microparticles from low melting fats, i.e. milk fat and a modified, diacylglycerol-based milk fat analog, using the Supercritical Melt ...Micronization (ScMM) process. To this end, we first studied the phase equilibrium of systems containing each of the fats and carbon dioxide at high pressures using a Cailletet apparatus, in order to determine the operating window for the ScMM process. The micronization results showed that two main powder morphologies are obtained (spherical hollow particles and a mass sponge-like broken particles) depending on the ScMM process conditions. Both types of particles have a potential for being incorporated in refrigerated or frozen food products, as a structuring agent.
The ScMM (Supercritical Melt Micronization) process was applied for the production of microparticles from anhydrous milk fat (AMF) and a diacylglycerol-based modified milk fat (D-AMF). Both fats were able to dissolve ca. 30wt% CO2 in the studied pressure and temperature ranges, being the CO2 amount slightly higher for AMF. A melting point depression was observed in both systems in the presence of CO2. Two powder morphologies were obtained (spherical hollow particles and a mass sponge-like broken particles) depending on the ScMM process conditions. The concentration of CO2 in the fat melt was the main process variable affecting the particle morphology, followed by the temperature of the melt. The small broken particles originated from the breakage of spherical fat particles that solidified before all CO2 could escape from the atomized droplets. While the hollow spheres had a tendency to agglomerate, the broken microparticles constituted a free-flowing powder as long as they were stored at low temperatures (up to −18°C). Both types of particles have a potential for being incorporated in refrigerated or frozen food products as a structuring agent.
Aim of this experimental work was to investigate the possibility of producing fruit powders without employing drying aid and to investigate the effect of drying temperatures on the final powder ...characteristics. Raw fruit materials (banana puree, strawberry puree and blueberry concentrate) were processed using three different drying techniques each operating at a different temperature conditions: vacuum-drying (-27-17 °C), Spray-drying (130-160 °C) and PGSS-drying (112-152 °C). Moisture content, total colour difference, antioxidant activity and sensory characteristics of the processed fruit powders were analysed. The results obtained from the experimental work indicate that investigated fruit powders without or with minimal addition of maltodextrin can be produced. Additionally, it was observed that an increase in process temperature results in a higher loss of colour, antioxidant activity and intensity of the flavour profile.
Most pharmaceutical compounds are administered to the human body as tablets or by injection. If the dissolution of a drug is low, high dosage is needed and hence may cause some side effects to the ...human body. One method of enhancing the dissolution rate of a drug into the biological environment is to reduce the particle size. Cyclosporine A, one of the immunosuppressant drugs that have been commonly used for the treatment of respiratory tract infections, was chosen as the drug of interest since it has low solubility and high permeability (Class 2) in water. The phase behaviour of the cyclosporine–carbon dioxide (CO
2) system was investigated prior to the micronization process. The melting point of cyclosporine substantially decreased from 150
°C at 1
bar to 25
°C at 55
bar when exposed to CO
2 at high pressure. Micron-sized cyclosporine was successfully produced by both rapid expansion of supercritical solution (RESS) and particles from gas-saturated solution (PGSS) techniques. After micronization, the average particle size of cyclosporine precipitated by both techniques was found to be less than 1
μm, which is related to a 97% reduction compared with the unprocessed cyclosporine. No significant change in the morphology and particle size was observed with respect to the extraction temperature and pre-expansion pressure, whilst an increase in nozzle diameter resulted in a slight increase in particle size and decrease in degree of aggregation. The fine particle mass (FPM) of micronized cyclosporine produced by RESS and PGSS was found to be 48 and 59%, respectively.
Alpha lipoic acid (ALA), an active substance in anti-aging products and dietary supplements, need to be masked with an edible polymer to obscure its unpleasant taste. However, the high viscosity of ...the ALA molecules prevents them from forming microcomposites with masking materials even in supercritical carbon dioxide (scCO
2
). Therefore, the purpose of this study was to investigate and develop a novel production method for microcomposite particles for ALA in hydrogenated colza oil (HCO). Microcomposite particles of ALA/HCO were prepared by using a novel gas-saturated solution (PGSS) process in which the solid-dispersion method is used along with stepwise temperature control (PGSS-STC). Its high viscosity prevents the formation of microcomposites in the conventional PGSS process even under strong agitation. Here, we disperse the solid particles of ALA and HCO in scCO
2
at low temperatures and change the temperature stepwise in order to mix the melted ALA and HCO in scCO
2
. As a result, a homogeneous dispersion of the droplets of ALA in melted HCO saturated with CO
2
is obtained at high temperatures. After the rapid expansion of the saturated solution through a nozzle, microcomposite particles of ALA/HCO several micrometers in diameter are obtained.
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