Evolution of Hemodialysis Technology
Sirshendu De, Anirban Roy in Hemodialysis Membranes, 2017
Figure 2.7c depicts the thermodynamic interpretation of this phase inversion mechanism. The phase diagram is a triangle with the pure polymer, pure solvent, and pure NS at the three vertices. Any composition inside the triangle is a mixture of the three. Point A depicts the initial membrane concentration, which on immersing in water undergoes phase inversion. Point A lies outside the binodal curve that joins point P′ to the solvent NS axis. This binodal curve can be obtained from cloud point or simple titration experiments. Dilute polymeric solutions of various concentrations are prepared and distilled water is then added and the solution stirred. The point where the solution turns turbid and turbidity persists is considered as the cloud point. Various compositions of solvent, NS, and polymer can thus be plotted to get the binodal curve. As mentioned earlier, the solvent diffuses out and the NS diffuses in. Point B is the first point where precipitation occurs. Point C is the point when enough solvent has diffused out, yielding a very high viscous phase that can be regarded as solid, which is therefore referred to as point of solidification. Finally, the matrix reaches point D, which yields the final membrane composition. At this point, the two phases are in equilibrium, the polymer lean phase (P), which comprises the pores, and the polymer-rich phase (P′), which forms the membrane structure, with D determining the overall porosity of the membrane. This complete process is often referred to as “demixing.”
Genosomes (DNA−Lipid Complexes)
Danilo D. Lasic in LIPOSOMES in GENE DELIVERY, 2019
Better characterization of genosomes is obtained by the phase diagram study. In the phase space of lipid and DNA concentration a property, such as precipitation (solubility gap), turbidity, size, ζ potential, as well as transfection activity and gene expression in vivo/in vitro, and similar properties, is measured. Figure 7-3 shows a phase diagram of a typical system. Around charge neutralization (ρ = 1) the system precipitates. Also, at higher lipid and DNA concentrations there is obviously phase separation or formation of a viscous phase, which is a well-known effect observed by pure lipid and pure DNA which form a liquid crystalline phase at higher concentrations (lipids typically above 30 wt% and DNA, in the 3 to 10 kb size range, above 15 mg/mL). The solubility gap, as well as characteristics of soluble complexes, depends on the nature of cationic and neutral lipids and the size of the liposomes. Preliminary data indicate that complexes are smaller and less turbid at higher temperatures, which may indicate nonelectrostatic contributions.
Structures and Properties of Self-Assembled Phospholipids in Excess Water
E. Nigel Harris, Thomas Exner, Graham R. V. Hughes, Ronald A. Asherson in Phospholipid-Binding Antibodies, 2020
If two phospholipids, which are nearly identical in size and shape, are mixed then the two component lipids will be completely miscible over the entire composition range in both the gel- and liquid-crystalline phases. This two-component binary system containing various molar ratios of the mixtures will exhibit calorimetrically a single-endothermic phase transition, corresponding to the gel to liquid-crystalline phase transition. The transition curves for the mixtures are slightly broadened in comparison with those of the pure component lipids. Each curve, however, has characteristic onset and completion temperatures positioned at the beginning and ending of the transition curve, respectively. These characteristic temperatures can be determined by the extrapolation of the maximal peak slopes from the two sides of the phase transition curve with the baseline. The phase diagram is constructed by plotting the onset and completion temperatures, after proper correction for the finite width of the transition curves of the pure components, as a function of the relative concentration of the higher melting component; these onset and completion temperature points then define the solidus and liquidus curve, respectively, in the temperature-composition binary phase diagram.
Improved anti-inflammatory effect of curcumin by designing self-emulsifying drug delivery system
Published in Drug Development and Industrial Pharmacy, 2021
Muhammad Hanif, Nabeela Ameer, Muhammad Khalid Mahmood, Ahmed Shehzad, Muhammad Azeem, Hafsa Latif Rana, Muhammad Usman
The objectives of present study were to design, prepare, and characterize Cur SEDDS, and assess its release and anti-inflammatory effect of Cur in albino rats. In this study, to develop an SEDDS containing poorly water-soluble Cur, various oils, surfactants, and cosurfactants were selected to optimize the formulation. The solubility of Cur in various oils and cosurfactants was investigated to find suitable ingredients with a good solubilizing capacity. Pseudo-ternary phase diagram was also constructed. Furthermore, its quality in vitro and its bioavailability in mice in vivo were assessed. The promising results such as increased solubility, enhanced oral bioavailability, anti-inflammatory activity obtained through formulation development of Cur SEDDS are discussed here.
Skin pigmentation improvement with resveratrol microemulsion gel using polyoxyethylene hydrogenated castor oil
Published in Drug Development and Industrial Pharmacy, 2023
Lu Cao, Xiaoyan Li, Jing Zhao, Qing Du, Jiening Dun
The pseudo-ternary phase diagram was established at room temperature. Glycerol triacetate was used as the oil phase, polyoxyethylene 40 hydrogenated castor oil(RH-40) as an emulsifier, and polyethylene glycol 400(PEG-400) as a co-emulsifier. First, the emulsifier and co-emulsifier were mixed with a mass ratio (Km) of 1:1, 2:1, and 3:1, after which the oil phase was mixed with a mass ratio of 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8 and 1:9. In the constant temperature magnetic agitator (Henan Great Wall Technology and Trade Co., LTD.), the distilled water was added to the mixture drop by drop until the formation of a transparent, transparent, uniform microemulsion. The amount of each component was recorded, and the pseudo-ternary phase diagram was drawn according to the mass percentage of oil, water, and mixed emulsifier at the critical point. Four points were randomly selected in the microemulsion region with Km value of 2:1, and four prescriptions were obtained to prepare blank microemulsion according to the ratio of four components. The microemulsion’s appearance, particle size, PDI, centrifugal stability, and maximum drug loading were used as evaluation indexes to screen the microemulsion prescription.
Enhancement of the intestinal absorption of bortezomib by self-nanoemulsifying drug delivery system
Published in Pharmaceutical Development and Technology, 2020
Mohammad Mahmoudian, Hadi Valizadeh, Raimar Löbenberg, Parvin Zakeri-Milani
Nine formulations with different ratio of compositions (Table 1) were prepared for constructing the ternary phase diagram. The ternary phase diagram was constructed to identify the droplet size regions for SNEDDSs. The ratio of oil, surfactant, and co-solvent was considered in an area of 10–30, 60–80, and 10–30 (%w/w), respectively. According to the ternary phase diagram (Figure 1), following by increasing the proportion of the surfactant the droplet size of self-emulsion is decreasing. While higher oil ratio resulted in significantly increasing in the droplet size of the prepared SNEDD. The region of nanoemulsion was selected by which a droplet size of ˂100 nm would be obtained. Based on the obtained data, a SNEDDS composed of glycerol monooleate/Tween 80/Transcutol P at a ratio of 1:8:1 was considered as an optimized formulation for further studies.
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