Influence of chirality on protein corona formation of low-fouling chiral poly(2-oxazoline) coated nanoparticles

Low-fouling polymers play a crucial role in the development of therapeutic nanoparticles (NPs), which are commonly described as nanomedicines. These hydrophilic polymers are typically designed to favourably alter the protein corona that forms around a NP by reducing the binding of opsonins, resulting in reduced immune recognition and clearance. The polymer specific proteome of the corona is mainly dictated by the physicochemical properties of the polymer and several parameters such as hydrophilicity and charge have been explored to regulate its composition. To date, there has been little attention given to the influence of the chirality of the hydrophilic polymer on the composition of the corona. Water-soluble poly(2,4-dialkyl-2-oxazoline)s (PdOx) are a unique synthetic polymer class to explore the effect of chirality as they can be rendered chiral if enantiopure monomers are used for their synthesis. Herein we prepared two water-soluble poly(2,4-dimethyl-2-oxazoline)s (PdMeOx) of different handedness, alongside racemic PdMeOx and the well-established low-fouling structural isomer poly(2-ethyl-2-oxazoline) (PEtOx). All polymers were equipped with sulphur-containing xanthate moieties with high end-group fidelity, which enabled anchoring to gold nanoparticles (AuNPs) as a useful handle for evaluation of the polymer-specific fouling. It was revealed that a hard corona formed after exposing the coated AuNP to human plasma proteins as investigated by dynamic light scattering, SDS-PAGE and PierceTM bicinchoninic acid protein assay (BCA) revealing a similar protein adsorption between PEtOx and all three PdMeOx. Moreover, a detailed proteomics study using liquid chromatography coupled to mass spectrometry (LC–MS/MS) was performed and analysed by label-free quantitation (LFQ). Overall, the PdMeOx systems showed similar human plasma protein corona profiles compared to the PEtOx control. However, between the R- and S-PdMeOx enantiomers differences in protein population abundances were observed, suggesting the propensity for specific interaction of chiral PdOx with different elements of the proteome. Overall, the present study introduces PdMeOx as a chiral, low fouling polymer system, which can reduce protein fouling in a similar magnitude to the PEtOx control. Importantly, we provide a first insight into how changes in the chirality of PdMeOx can influence the components of the protein corona, which will inform the future design of PdOx nanotherapeutics.