Physical Chemistry of Bilirubin: Binding to Macromolecules and Membranes
Karel P. M. Heirwegh, Stanley B. Brown in Bilirubin, 1982
The solubility of bilirubin acid in several solvents has been measured (Figure 3).2 The solubility in apolar media, such as n-hexane, is low, less than 1 µM, and generally increases with solvent polarity, to more than 10 mMin dimethylsulfoxide (DMSO). Aromatic hydrocarbons (benzene) are better solvents than the aliphatic, and an asymmetric structure seems to promote dissolution (toluene, xylene). Pyrrole and pyridine, which are asymmetric aromatic and polar, are good solvents. Dichloromethane and chloroform are asymmetric and are better solvents than carbon tetrachloride. Aliphatic alcohols do not dissolve bilirubin acid, indicating that ability to form hydrogen bonds is not sufficient. Acetone, on the other hand, dissolves some bilirubin, and here again the asymmetric ketones are better solvents. It is interesting to note that increasing chain length does not increase solubility, as illustrated by di-isobutyl ketone which dissolves less bilirubin than methyl isobutyl ketone or acetone. Also, ethyl acetate is a better solvent than long-chain esters, olive oil and lard, which in fact dissolve very little bilirubin.
Antiviral Nanomaterials as Potential Targets for Malaria Prevention and Treatment
Devarajan Thangadurai, Saher Islam, Charles Oluwaseun Adetunji in Viral and Antiviral Nanomaterials, 2022
This technique uses a lipid phase containing lipid excipients, and the therapeutic moiety is solubilized in a volatile organic solvent. Other excipients, such as a stabilizing agent, are dissolved to make an aqueous phase. To obtain a small droplet-formed emulsion (O/W), the lipid phase is applied to the aqueous phase, followed by high-energy homogenization or sonication. Furthermore, the organic solvent is removed by evaporation or decreased pressure. This process subsequently results in the formation of lipid NPs. Ethyl acetate is an extensively used organic solvent because it offers better toxicological profile as compared to earlier used solvents, such as dichloromethane and chloroform (Pradhan et al. 2017, 2020). The NPs are washed repeatedly with distilled water by ultracentrifugation, and then the pellets of lipid NPs are collected. The physico-chemical properties of prepared nanoparticles are influenced by experimental parameters, such as processing temperature, solvent-evaporation method, aqueous-phase length, surfactant quantity, and polymer-molecular weight (Pradhan et al. 2016b). This is well suited for lipophilic and thermolabile drugs because this technique does not involve thermal stress. However, this method has limitations, such as time consumption and coalescence during the solvent evaporation (Singh et al. 2016).
Asphyxia due to Metabolic Poisons
Burkhard Madea in Asphyxiation, Suffocation,and Neck Pressure Deaths, 2020
Due to the change of colour to the blood by increasing levels of COHb, spectrophotometric methods have been used for decades to determine the proportion of this form of haemoglobin [29] although accurate and more sensitive headspace gas chromatography–mass spectrometry (GC−MS) methods are also available today. These latter alternatives also offer better opportunities to analyze putrefied samples [13]. Small amounts (less than 0.5 per cent) of COHb may be detected in normal subjects due to the endogenous production of CO in the body, and heavy smokers can show up to 10 per cent COHb in their blood. Further, exposure to paint strippers containing dichloromethane is another source of elevated COHb levels that should not be overlooked. Dichloromethane is metabolized to CO in the body, and the COHb levels may continue to increase after interrupted exposure until the accumulated dichloromethane is eliminated. Although the hepatic conversion of dichloromethane to CO was discovered in the 1970s [24] and the toxicity of this solvent was reported as a workplace hazard, occasional fatalities are still encountered [19]. The toxicity is, however, mainly due to the central nervous system effects of dichloromethane itself and COHb elevations are moderate. In fire victims, levels exceeding 50 per cent saturation are usually seen in cases where carbon monoxide is considered to be solely responsible for the death, and somewhat higher percentages are seen in subjects who have inhaled vehicle exhaust fumes [16]. This discrepancy is assumed to be due to a contributory effect of other compounds in the smoke inhaled by fire victims [6].
Electrospinning of linezolid loaded PLGA nanofibers: effect of solvents on its spinnability, drug delivery, mechanical properties, and antibacterial activities
Published in Drug Development and Industrial Pharmacy, 2020
Tugba Eren Boncu, Nurten Ozdemir, Aylin Uskudar Guclu
In the current study, the spinnability and properties of poly(d,l-lactic-co-glycolic) acid (PLGA) nanofibers associated with solvent properties were investigated. PLGA is a nontoxic, highly stable, biodegradable, and biocompatible polymer approved by the United States Food and Drug Administration (FDA) for pharmaceutical application [17,18]. Linezolid, the first oxazolidinone antibiotic approved by the FDA and particularly effective for soft tissue infections, was used to prepare the electrospun nanofibers. Linezolid form III was chosen for its pharmacologically active and stable form of linezolid [19,20]. 1,1,1,3,3,3-Hexafluoro-2-propanol (HFIP), a frequently preferred solvent in the electrospinning process, was used because of its sufficiently low surface tension and its sufficiently high dielectric constant and volatility [1,21–23]. In addition, different ratios of dichloromethane (DCM) and dimethylformamide (DMF) were also used as solvent systems.
Polymer type effect on PLGA-based microparticles preparation by solvent evaporation method with single emulsion system using focussed beam reflectance measurement
Published in Journal of Microencapsulation, 2022
Muhaimin Muhaimin, Anis Yohana Chaerunisaa, Roland Bodmeier
The type and physical properties of polymer have influenced the opacity level of particle. All microparticles have different opacity level (Figure 2(a1–c1)). It is effect of polymer solubility in solvent dichloromethane. Polymers have high solubility in dichloromethane took longer time to solidify and stayed longer in the semi solid, the dispersed phase became more concentrated before it completely solidified. The polymer matrix is dense when it is allowed to shrink for a longer period of time. So, a gradual shrinkage of the droplet into solid microparticles was observed remain translucent. Mean diameter of polymeric microparticles ranged from 42 to 64 µm (FBRM) (Table 1). The particle size mean of microparticles which was prepared using the high viscosity of polymer organic solution were larger than those prepared with the low viscosity of polymer organic solution. This is caused by the more rapid solidification process occurring at the surface of embryonic microparticle droplets which resist in extensive shrinkage of embryonic microparticles droplets. Based on microscopy data, the square weighted mean of a chord length distribution is better estimation for mean particle diameter (Table 1).
Decreasing acute toxicity and suppressing colorectal carcinoma using Sorafenib-loaded nanoparticles
Published in Pharmaceutical Development and Technology, 2020
Ningxi Li, Yan Chen, Huimin Sun, Tingwenli Huang, Tianyu Chen, Yichun Jiang, Qian Yang, Xiaoyan Yan, Min Wu
Since sorafenib is highly hydrophobic, W/O/W solvent evaporation was used to prepare the NPs in order to improve DL% (Acharya and Sahoo 2011). Several factors were optimized during S-NP preparation. The weight ratio of sorafenib and PEG-PLGA was optimized (1.5:10, w/w) to achieve a smaller size and higher DL (Figure 1(A)), and the sonication power was optimized for size and EE (Figure 1(B)). We used 40 W of sonication to form the primary W/O emulation, and 80 W for subsequent W/O/W emulation to obtain S-NPs. We also tested different organic phases and obtained the highest DL and smallest size of S-NPs with a mixture of dichloromethane/acetone (4/1, v/v) (Figure 1(C)). Dichloromethane can be removed quickly, and it is less toxic than chloroform. We optimized the concentration of PVA at 0.5% PVA (w/v), since as PVA concentration decreased, particle size first increased and then decreased, while EE% continually increased (Figure 1(D)).
Related Knowledge Centers
- Carbon Tetrachloride
- Chemical Reaction
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- Organochlorine Chemistry
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- Chloroform
- Chemical Polarity
- Chloromethane
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