The Impact of Polyethylene Glycol Lipid Anchors on the Physicochemical Properties, Protein Corona, Function, and Biodistribution of Lipid Nanoparticles

When
introduced into biological systems, the function and biodistribution
of lipid nanoparticles (LNPs) are affected by the biomolecular coronas
they acquire. Corona composition is determined by the biophysical
and chemical properties of the particles and the contents of the biofluids.
Polyethylene glycol (PEG) polymers, anchored using lipids that partition
into LNPs during formulation, are key to LNP stability in circulation.
It is, however, not well-studied how different PEG-lipid anchors,
with different acyl chain lengths, headgroup/linker chemistries, and
desorption rates (PEG “shedding” from nanoparticles)
can affect corona composition and LNP function. Here, we examined
how common PEG-lipid anchors affect (1) in vivo biodistribution
in C57BL/6 mice, (2) corona content (using mass spectrometry-based
proteomics), (3) LNP biophysical characteristics (using single-particle
automated Raman trapping analysis (SPARTAⓇ)), and
(4) in vitro particle function (using cellular uptake
and cargo delivery assays). Following nanoparticle formulation with
clinically approved, commonly used PEG anchors, we found that the
LNP biodistribution is strongly impacted, particularly in the liver,
spleen, bone marrow, and lung. We then tested a wide range of lipid
ratio combinations using high-throughput evaluation in vitro. Despite being minor LNP components (by molar ratio), the PEG-lipid
anchors strongly impact the chemical characteristics, corona content,
and particle function. These findings reveal structure–activity
relationships between PEG-lipid anchor chemistry and functional LNP
biodistribution, with implications for rational LNP design.