Royal College of Surgeons in Ireland
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Understanding the role and impact of Poly (Ethylene Glycol) (PEG) on nanoparticle formulation: implications for COVID-19 vaccines

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journal contribution
posted on 2022-08-03, 15:46 authored by Esperanza Padín González, Pearl Lancaster, Massimo Bottini, Paolo Gasco, Lang Tran, Bengt Fadeel, Terence Wilkins, Marco MonopoliMarco Monopoli

Poly (ethylene glycol) (PEG) is a widely used polymer in a variety of consumer products and in medicine. PEGylation refers to the conjugation of PEG to drugs or nanoparticles to increase circulation time and reduce unwanted host responses. PEG is viewed as being well-tolerated, but previous studies have identified anti-PEG antibodies and so-called pseudoallergic reactions in certain individuals. The increased use of nanoparticles as contrast agents or in drug delivery, along with the introduction of mRNA vaccines encapsulated in PEGylated lipid nanoparticles has brought this issue to the fore. Thus, while these vaccines have proven to be remarkably effective, rare cases of anaphylaxis have been reported, and this has been tentatively ascribed to the PEGylated carriers, which may trigger complement activation in susceptible individuals. Here, we provide a general overview of the use of PEGylated nanoparticles for pharmaceutical applications, and we discuss the activation of the complement cascade that might be caused by PEGylated nanomedicines for a better understanding of these immunological adverse reactions.


European Union’s Horizon 2020 Research and Innovation Programme under grant agreement no. 760928 (BIORIMA)



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Published Citation

Padín-González E, et al. Understanding the role and impact of Poly (Ethylene gGycol) (PEG) on nanoparticle formulation: implications for COVID-19 vaccines. Front Bioeng Biotechnol. 2022;10:882363.

Publication Date

7 June 2022

PubMed ID



  • Chemistry


Frontiers Media S.A.


  • Published Version (Version of Record)