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Enhanced Scaffold Fabrication Techniques for Optimal Characterization
Published in Naznin Sultana, Sanchita Bandyopadhyay-Ghosh, Chin Fhong Soon, Tissue Engineering Strategies for Organ Regeneration, 2020
Tshai Kim Yeow, Lim Siew Shee, Yong Leng Chuan, Chou Pui May
In solid-liquid phase separation, the first step is the preparation of polymer solution by dissolving polymer in a solvent. The polymer solution is then poured into a mold and cooled to a set quenching temperature until the solution becomes solidified. The separation of polymer-rich phase from polymer-lean phase occurs during quenching as the polymer solution becomes highly unstable. The frozen polymer solution is subsequently subjected to freeze-extraction or sublimation for the removal of polymer-lean phase (Ma and Zhang 1999, Ho et al. 2004). Ultimately, only polymer-rich phase remains as solidified matrix. The compressive modulus of PLA scaffolds prepared via phase separation method was reportedly 20 times higher than that of material prepared using salt-leaching technique (Ma et al. 2001). The profound modulus was attributed to the pore size of scaffolds prepared via solid-liquid phase separation ranging from 10-100 micron. To further increase the osteoconductivity of scaffolds, composite scaffolds of polymer and ceramic compound such as hydroxyapatite (HA) were also prepared by blending HA with polymer solution prior to phase separation. HA serving as reinforcing phase in polymeric matrix aided to enhance compressive modulus of the scaffolds which was also coupled with improved in vitro and in vivo efficacies promoting bone ingrowth (Wang et al. 2007).
Role of Tumor Cell Membrane in Hyperthermia
Published in Leopold J. Anghileri, Jacques Robert, Hyperthermia In Cancer Treatment, 2019
The two important characteristics of the phase separation process are (1) phase transition is a cooperative process where clusters of a few molecules existing for a short time do not constitute a domain — a minimal area of about 50 nm2 is needed;20 and (2) in the rigid phases the lipid molecules exhibit a long-range order within the plane of the membrane. There are defined conditions for the existence of a phase, and the appearance of the all-transconfiguration of the acyl chains (rigid and parallel) is related to an ordered arrangement of the molecules in close contact, forming a separated area within a mixture of lipid molecules in the fluid state. These types of “crystal in fluid” domains are special structures which are morphologically detected by electron microscopy. In a domain, one component of the mixture may be involved but one or more components can be incorporated in a phenomenon of “cocrystallization”.21
Isolation, Fractionation, and Analysis of Nonhistone Chromosomal Proteins
Published in Lubomir S. Hnilica, Chromosomal Nonhistone Proteins, 2018
Leokadia Klyszejko-Stefanowicz, Lubomir S. Hnilica
Aqueous solution containing substantial concentrations of two water-soluble polymers will often separate into two distinct phases, each rich in one of the two polymeric components, yet both containing 80 to 95% of water. Such phase separation system may be used for gentle fractionation of biological materials, since its highly aqueous nature allows retention of biological activity.296 By only a few manual extractions it enables large-scale fractionation of nucleic acids on the basis of their degree of double-helical structure, as well as a rapid separation of DNA from RNA and gentle removal of proteins from either nucleic acid.
Improvement of dissolution profile of eplerenone with solidified self-emulsifying drug delivery systems (S-SEDDS)
Published in Drug Development and Industrial Pharmacy, 2023
Rawan Ranna, Burcu Uner, Neslihan Ustundag Okur, Cetin Tas
Physical stability is critical for the formulation’s efficiency since it could be impacted by the sedimentation of the active ingredient in the excipient mixture. Because of the formulations’ low physical stability, it might be occurred to phase separation, negatively affecting the bioavailability, and therapeutic effectiveness [22]. The selected EPL-L-SEDDS and EPL-S-SEDDS formulations were subjected to three weeks of stability testing to determine the most efficient SEDDS formulation. Six heating and cooling cycles have been performed upon these formulations, involving 48 h of cooling at 4 °C accompanied by 48 h of heating at 40 °C. After centrifugation at 4000 rpm for 30 min, the samples were then subjected to two freeze-thaw stress cycles, which also involved 48 h of freezing at −4 °C followed by 48 h of thawing at 40 °C. After each cycle completion, the formulations were analyzed for phase separation visually and DS, PDI, and ZP values.
Current trends in PLGA based long-acting injectable products: The industry perspective
Published in Expert Opinion on Drug Delivery, 2022
Omkara Swami Muddineti, Abdelwahab Omri
Microencapsulation technique is used to prepare microspheres, including ionic gelation, spray drying, coacervation, solvent evaporation, extraction, and interfacial polymerization to harden and separate the particles [49]. Out of all the techniques, solvent evaporation/extraction is the most widely used technique for manufacturing the marketed PLGA-based microspheres. Briefly, the solvent evaporation/extraction method depends on the emulsification of the polymer (organic) solution in a continuous (aqueous) phase and later formation of microspheres via precipitation. The solvent used to solubilize the polymer and active pharmaceutical ingredient (API) should have sufficient solubility in the aqueous phase to partition and precipitation to prepare desired microparticles. Coacervation and phase separation technique is also used to manufacture PLGA-based microspheres at higher scales [50]. In this technique, polymer (mixture of polymers) solution is separated into a dilute polymer phase and concentrated coacervate phase, which is in equilibrium. Phase separation can be initiated using a change in temperature, the addition of non-solvent, and a change in ionic strength. Further, these changes induce interaction between polymers over polymer–solvent interaction, resulting in polymer dehydration. Thermal or chemical treatment is frequently used to stabilize the coacervate emulsion droplets to form microspheres, which may not apply to sensitive molecules such as proteins.
Antioxidant and cytoprotective properties of loganic acid isolated from seeds of Strychnos potatorum L. against heavy metal induced toxicity in PBMC model
Published in Drug and Chemical Toxicology, 2022
Alagarsamy Abirami, Simran Sinsinwar, Perumal Rajalakshmi, Pemaiah Brindha, Yamajala B. R. D. Rajesh, Vellingiri Vadivel
Among the four extracts, maximum antioxidant activity was observed in methanol extract (81.22%), hence it was chosen for further purification using liquid-liquid partitioning according to the method of Ajileye et al. (2015). Liquid- liquid partitioning is widely used for separating compounds and in this technique it is possible to separate the compounds by applying phase separation between two immiscible solvents such as hexane/water, chloroform/water and ethyl acetate/water. The methanolic extract was dried in rotovapor and the dried extract was re-dissolved in 100 mL of distilled water and then partitioned with 2 × 200 mL of hexane in a separating funnel, mixed well and kept undisturbed for 2 h for phase separation and the upper hexane fraction was collected as LF1. The remaining aqueous phase was mixed with 2 × 200 mL of chloroform and phase separated as described above and the chloroform fraction was collected as LF2. Then, 2 × 200 mL of ethyl acetate was added to the aqueous phase and allowed to phase separate and the ethyl acetate fraction was collected as LF3. The remaining aqueous layer was saved as LF4. All the fractions (LF1–LF4) were subjected to solvent evaporation, re-dissolved in respective solvents at 10 mg/mL concentration and evaluated for DPPH radical scavenging activity.