Understanding the biomolecular corona formation at the nano-bio interface

Introduction Engineered polymeric nanoparticles (NPs) are promising candidates in controlled and targeted therapeutic drug delivery applications. However, formation of a biomolecular corona in physiological environments alters the synthetic identity of the NPs.[1] This influences cell-NP interactions, often leading to immune recognition and rapid clearance of the NPs from circulation.[2] In this context, NPs composed of protein-resistant and immune-modulating materials are of interest.

Method Surface-initiated atom transfer radical polymerization (SI-ATRP) and surface-initiated reverse addition fragmentation chain-transfer (SI-RAFT) within mesoporous silica template particles allows the fabrication of polymeric replica NPs with predetermined composition and monodisperse size distribution. To impart a low-fouling and stealth character to the NPs, polyethylene glycol (PEG)-based monomers were used as backbone monomers. Furthermore, the additional incorporation of end-functionalised monomers such as 2-hydroxyethyl methacrylate (HEMA) for a hydroxyl functionality and ethanolamine methacrylate (EAMA) for an amine functionality, enabled decoration of the NPs with fluorescent labels as well as immune-associated biomolecules such as heparin. The additional incorporation of heparin has the potential to further improve the NPs bioavailability. The NPs were characterised by dynamic light scattering (DLS) and electron microscopy. The performance regarding their biocompatibility was evaluated through in vitro and ex vivo assessments in human plasma and blood.

Results Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses revealed the spherical morphology and monodispersity of PEG-NPs. DLS measurements indicated a particle size of ~230 nm and neutral zeta potential of ~1 mV. Sodium-dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated a reduction in plasma protein adsorption on PEG-NPs (indicative of a low-fouling nature) as compared to silica template particles. Confocal laser scanning microscopy analyses and enzyme-based activity assays confirmed incorporation of fluorescent labels and heparin respectively in the NP architecture. Furthermore, cell-NP association studies in human whole blood were performed to characterize the NPs stealthiness.

Conclusion PEG-based monomers confer a low-fouling character and the additional monomers impart functional versatility to the NPs. The PEG-NPs present a platform for investigating the link between biomolecular corona formation and downstream immune responses. Decoding the immunological aspects of the biomolecular corona, and establishing an immunogenic link towards NP clearance, will further assist in understanding the possibilities of immunoevasive NPs. This may ultimately be employed in the development of advanced long circulating NPs for the controlled delivery of drugs for the therapeutic treatment of disease.

Publication History

Article published online:
20 February 2023

• References

• 1 Weiss AC, Kelly HG, Faria M, Besford QA, Wheatley AK, Ang CS, Crampin EJ, Caruso F, Kent SJ. Link between low-fouling and stealth: A whole blood biomolecular corona and cellular association analysis on nanoengineered particles. ACS nano 2019; 13 (05) pp 4980-4991
• 2 Cui J, De Rose R, Alt K, Alcantara S, Paterson BM, Liang K, Hu M, Richardson JJ, Yan Y, Jeffery CM, Price RI. Engineering poly (ethylene glycol) particles for improved biodistribution. ACS nano 2015; 9 (02) pp 1571-1580