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{"title":"Complex Micellization Behavior of the PolysorbatesnTween 20 and Tween 80","authors":"Hannah Knoch (11113421), Maximilian H. Ulbrich (8630550), Judith J. Mittag (3348152), Julia Buske (11113424), Patrick Garidel (4458682), Heiko Heerklotz (1894978)","doi":"10.1021/acs.molpharmaceut.1c00406.s001","DOIUrl":"https://doi.org/10.1021/acs.molpharmaceut.1c00406.s001","url":null,"abstract":"Polysorbates (PSs,nTweens) are widely used surfactant productsnconsisting of a sorbitan ring connecting up to four ethylene oxiden(EO) chains of variable lengths, one or more of which are esterifiednwith fatty acids of variable lengths and saturation degrees. Pharmaceuticalnapplications include the stabilization of biologicals in solutionsnand the solubilization of poorly water soluble, active ingredients.nThis study characterizes the complex association behavior of compendialnPSs PS20 and PS80, which is fundamentally different from that of single-componentnsurfactants. To this end, a series of demicellization experimentsnof isothermal titration calorimetry with different PS concentrationsnare evaluated. Their experiment-dependent heats of titration are convertedninto a common function of the state of a sample, the micellar enthalpy <i>Q</i><sub>m</sub>(<i>c</i>). These functions demonstratenthat initial micelles are already present at the lowest concentrationsninvestigated, 2 μM for PS20 and 10 μM for PS80. Initialnmicelles consist primarily of the surfactant species with the lowestnindividual critical micelle concentration (cmc). With increasing concentration,nthe other PS species gradually enter these micelles in the sequencenof increasing individual cmc’s and hydrophilic–lipophilicnbalance. Concentration ranges with pronounced slopes of <i>Q</i><sub>m</sub>(<i>c</i>) can be tentatively assigned to thenuptake of the major components of the PS products. Micellization andnthe variation of the micelle properties progress up to at least 10nmM PS. That means the published cmc values or ranges of PS20 and PS80nmay be related to certain, major components being incorporated intonand forming specific micelles but must not be interpreted in termsnof an absence of micelles below and constant properties, e.g., thensurface activity, of the micelles above these ranges. The micellizationnenthalpy curves differ quite substantially between PS20 and PS80 and,nin a subtler fashion, between individual quality grades such as highnpurity, pure lauric acid/pure oleic acid, super-refined, and Chinangrade.","PeriodicalId":522559,"journal":{"name":"Figshare","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147899325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}