A reactive oxygen species-scavenging ‘stealth’ polymer, poly(thioglycidyl glycerol), outperforms poly(ethylene glycol) in protein conjugates and nanocarriers and enhances protein stability to environmental and biological stressors

Richard d’Arcy, Farah El Mohtadi, Nora Francini , Carlisle R. DeJulius, Hyunmoon Back, Arianna Gennari, Mike Geven, Maria Lopez-Cavestany, Zulfiye Yesim Turhan, Fang Yu, Jong Bong Lee, Michael R. King, Leonid Kagan, Craig L. Duvall, Nicola Tirelli*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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This study addresses well-known shortcomings of poly(ethylene glycol) (PEG)-based conjugates. PEGylation is by far the most common method employed to overcome immunogenicity and suboptimal pharmacokinetics of, for example, therapeutic proteins but has significant drawbacks. First, PEG offers no protection from denaturation during lyophilization, storage, or oxidation (e.g., by biological oxidants, reactive oxygen species); second, PEG’s inherent immunogenicity, leading to hypersensitivity and accelerated blood clearance (ABC), is a growing concern. We have here developed an ‘active-stealth’ polymer, poly(thioglycidyl glycerol)(PTGG), which in human plasma is less immunogenic than PEG (35% less complement activation) and features a reactive oxygen species-scavenging and anti-inflammatory action (∼50% less TNF-α in LPS-stimulated macrophages at only 0.1 mg/mL). PTGG was conjugated to proteins via a one-pot process; molar mass- and grafting density-matched PTGG-lysozyme conjugates were superior to their PEG analogues in terms of enzyme activity and stability against freeze-drying or oxidation; the latter is due to sacrificial oxidation of methionine-mimetic PTGG chains. Both in mice and rats, PTGG-ovalbumin displayed circulation half-lives up to twice as long as PEG-ovalbumin, but most importantly─and differently from PEG─without any associated ABC effect seen either in the time dependency of blood concentration, in the liver/splenic accumulation, or in antipolymer IgM/IgG titers. Furthermore, similar pharmacokinetic results were obtained with PTGGylated/PEGylated liposomal nanocarriers. PTGG’s ‘active-stealth’ character therefore makes it a highly promising alternative to PEG for conjugation to biologics or nanocarriers.
Original languageEnglish
Pages (from-to)21304-21317
Number of pages14
JournalJournal of the American Chemical Society
Issue number46
Early online date11 Nov 2022
Publication statusPublished - 23 Nov 2022


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