Useful Principles for the Crystallization of Proteins
Hartmut Michel in Crystallization of Membrane Proteins, 1991
Polyethylene glycol is produced in a variety of polymer sizes. The low molecular weight species are oily liquids while those above 1000 at room temperature exist as either waxy solids or powders. The latter are preferable for easy dissolution. The size specified by the manufacturer is the mean molecular weight of the polymeric molecules, and the distribution of weights about that mean may vary appreciably. It is certainly broad for the very high molecular weight species. The most popular sizes currently in use are 1000, 4000, 6000, and 20,000. PEG in its commercial form does contain contaminants; this is particularly true of the high molecular weight forms such as 15,000 or 20,000. These may be removed by simple purification procedures27 or in the case of PEG 20,000 by dialysis in low-pass dialysis or collodian tubes. There have been reports that repurified PEG has proven more effective, and certainly the contiminants could be disadvantageous for some proteins.38
Binders in Pharmaceutical Granulation
Dilip M. Parikh in Handbook of Pharmaceutical Granulation Technology, 2021
Polyethylene Glycol is formed by the reaction of ethylene oxide and water under pressure in the presence of a catalyst. PEG is soluble in water and miscible with other grades of PEG. In tablet formulations, PEG’s of higher molecular weight can enhance the effectiveness of tablet binders by imparting plasticity to the granule; however, they have limited binding action by themselves [6,7]. When used above 5% w/w, it may prolong tablet disintegration. Nowadays, PEG’s are commonly used as binders in the melt granulation process. In this process, a powder blend containing 10–15% w/w of PEG 4000 or 6000 is heated to 70–75°C to obtain a paste-like mass that forms granules when mixed while cooling in an extruder. PEGs are versatile as low molecular or liquid PEG is mainly used as plasticizers while the higher molecular PEGs are used as tablet binders, polishing material, and as solid dispersion carriers to enhance the aqueous solubility of poorly soluble drugs [8].
Bowel disorders
Henry J. Woodford in Essential Geriatrics, 2022
Polyethylene glycol (PG) is a mixture of polymers that increase stool water content due to an osmotic effect. Molecules with a molecular weight of 3,350 or above are used because they cannot be absorbed by the gut (macrogol 3,350).12 PG has been shown to be effective in the treatment of faecal impaction (see page 286). It comes as a powder that is added to water, which removes the risk of dehydration. It is not metabolised by bowel bacteria and is not absorbed. Each sachet is usually mixed with 125 ml of water and up to eight sachets can be taken per day. This can require swallowing a significant volume of liquid and may be unsuitable for people with reduced oral intake or an impaired swallow. Starch-based thickening agents cannot be added to these solutions.
Folate conjugation improved uptake and targeting of porous hydroxyapatite nanoparticles containing epirubicin to cancer cells
Published in Pharmaceutical Development and Technology, 2020
Legha Ansari, Mansooreh Derakhshi, Elnaz Bagheri, Nasser Shahtahmassebi, Bizhan Malaekeh-Nikouei
Different methods have been applied to synthesize hydroxyapatite nanoparticles such as co-precipitation (Liu Y et al. 2010; Shan et al. 2012), hydrothermal (Yang et al. 2014; Yao et al. 2014), ultrasonic spray pyrolysis (Wakiya et al. 2010; Inukai et al. 2011). Also, different templates made of a variety of surfactants such as cetyltrimethylammonium bromide (CTAB) (Cai et al. 2007; Cai and Tang 2008; Qi et al. 2015), Pluronic P123 (Ye et al. 2010), Pluronic F127 (Cheah et al. 2012), poly (caprolactone) (PCL) and poly (vinyl alcohol) (PVA) (Singh et al. 2012) have been used in the previous studies. In the present study, we proposed to use the micellar template for producing hydroxyapatite (HAp) nanoparticles with desired morphology. Wet chemical methods such as micellar template, were applied to control growth factors and morphology of nanoparticles with uniform size distribution and mesoporous structure. In the first step, mesoporous hydroxyapatite nanoparticles synthesized via co-precipitation method in combination with micellar template. CTAB was applied as a micellar template. Poly (ethylene glycol) is one of the most widely applied synthetic polymers in biological applications due to its very great hydrophilicity and biocompatibility (Ivanova et al. 2014). Accordingly, at the second step HAp-PEG and HAp-PEG-FA nanoparticles were produced. Straightforward performance and reducing reaction time to obtain nanoparticles are the advantages of this approach.
Application of titanium dioxide (TiO2) nanoparticles in cancer therapies
Published in Journal of Drug Targeting, 2019
Selin Çeşmeli, Cigir Biray Avci
Harada et al. (2013) [20] at Osaka Prefecture University, used titanium dioxide nanoparticles in the form of encapsulated inside micelle. Polyethylene glycol, a polymer which is commonly used in medical applications, was used for the stabilisation of micelles and for improving the biocompatibility also decreasing the cytotoxicity of micelles. As the far-red light used in photodynamic therapy cannot penetrate into deeper part of tissues, researchers in this study preferred ultrasound. Because ultrasound does not harm the cells and also could able to go to the further sides inside cancer cells. They found that both healthy cells and HeLa cells, an immortal cell line took up these micelles and after the ultrasound was applied to the micelles; TiO2 nanoparticles generated reactive oxygen species (ROS) that are cytotoxic agents. As a result, ultrasound energy could be used in clinic with this application in order to target and kill the only tumour.
Acids produced by lactobacilli inhibit the growth of commensal Lachnospiraceae and S24-7 bacteria
Published in Gut Microbes, 2022
Emma J. E. Brownlie, Danica Chaharlangi, Erin Oi-Yan Wong, Deanna Kim, William Wiley Navarre
The Lachnospiraceae and S24-7 species are poorly studied, largely due to a paucity of cultured isolates, and their sensitivity to stress has not been extensively examined. The apparent acid sensitivity of both taxa relative to other species from the Bacteroidales and Clostridiales orders warrants further investigation. The S24-7 group of bacteria has been shown to be highly intolerant to hyperosmotic conditions.43 Indeed, osmotic-induced diarrhea caused by the administration of polyethylene glycol (as routinely occurs prior to colonoscopy procedures) leads to an extinction of these bacteria from the gut. An inability to survive acid stress could render both S24-7 and Lachnospiraceae susceptible to elimination from the gut under circumstances that lower the pH of the colon including chronic inflammation or certain drugs, food additives, or xenobiotics.
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