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Cleavable Polyethylene Glycol: 3,4-Epoxy-1-butene as a Comonomer to Establish Degradability at Physiologically Relevant pH
Version 2 2016-11-28, 17:48
Version 1 2016-11-28, 13:21
journal contribution
posted on 2016-11-28, 17:48 authored by Matthias Worm, Daniel Leibig, Carsten Dingels, Holger FreyPolyethylene
glycol (PEG) has been used for decades to improve
the pharmacokinetic properties of protein drugs, and several PEG-protein
conjugates are approved by the FDA. However, the nondegradability
of PEG restricts its use to a limiting molecular weight to permit
renal excretion. In this work, we introduce a simple strategy to overcome
the nondegradability of PEG by incorporating multiple pH-sensitive
vinyl ether moieties into the polyether backbone. Copolymerization
of 3,4-epoxy-1-butene (EPB) with ethylene oxide via anionic ring-opening
polymerization (AROP) provides access to allyl moieties that can be
isomerized to pH-cleavable propenyl units (isoEPB).
Well-defined P(EPB-co-EG) copolymers (Đ = 1.05–1.11) with EPB contents of ∼4 mol% were synthesized
in a molecular weight range of 3000 to 10000 g mol–1. 1H NMR kinetic studies served to investigate acidic
hydrolysis in a pH range of 4.4 to 5.4 and even allowed to distinguish
between the hydrolysis rates of (E)- and (Z)-isoEPB units, demonstrating faster hydrolysis
of the (Z)-isomer. SEC analysis of degradation products
revealed moderate dispersities Đ of 1.6 to
1.8 and consistent average molecular weights Mn of ∼1000 g mol–1. The presence of
a defined hydroxyl end group permits attachment to other functional
molecules. The novel pH-degradable PEGs combine various desirable
properties such as excellent long-term storage stability and cleavage
in a physiologically relevant pH-range that render them promising
candidates for biomedical application.
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protein drugsiso EPBpharmacokinetic propertiespH rangehydrolysis ratesmolnondegradabilityFDACleavable Polyethylene Glycolring-opening polymerizationAROPweight range1 H NMRdispersities ĐEPB contentspH-sensitive vinyl ether moietiespolyether backbonedegradation productsallyl moietieshydroxyl end groupPEG-protein conjugatesRelevant pH Polyethylene glycolpH-cleavable propenyl units-1-buteneethylene oxideweights M nnovel pH-degradable PEGsSEC analysisacidic hydrolysisstorage stability
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