Protein Binding Leads to Reduced Stability and Solvated Disorder in the Polystyrene Nanoparticle Corona.

Understanding the conformation of proteins in the nanoparticle corona has important implications in how organisms respond to nanoparticle-based drugs. These proteins coat the nanoparticle surface, and their properties will influence the nanoparticle's interaction with cell targets and the immune system. While some coronas are thought to be disordered, two key unanswered questions are the degree of disorder and solvent accessibility. Here, a model is developed for protein corona disorder in polystyrene nanoparticles of varying size. For two different proteins, it is found that binding affinity decreases as nanoparticle size increases. The stoichiometry of binding, along with changes in the hydrodynamic size, supports a highly solvated, disordered protein corona anchored at a small number of attachment sites. The scaling of the stoichiometry versus nanoparticle size is consistent with disordered polymer dimensions. Moreover, it is found that proteins are destabilized less in the presence of larger nanoparticles, and hydrophobic exposure decreases at lower curvatures. The observations hold for proteins on flat polystyrene surfaces, which have the lowest hydrophobic exposure. The model provides an explanation for previous observations of increased amyloid fibrillation rates in the presence of larger nanoparticles, and it may rationalize how cell receptors can recognize protein disorder in therapeutic nanoparticles.

Glycopolymeric Nanoparticles Enrich Less Immunogenic Protein Coronas, Reduce Mononuclear Phagocyte Clearance, and Improve Tumor Delivery Compared to PEGylated Nanoparticles.

Nanoparticles (NPs) offer significant promise as drug delivery vehicles; however, their in vivo efficacy is often hindered by the formation of a protein corona (PC), which influences key physiological responses such as blood circulation time, biodistribution, cellular uptake, and intracellular localization. Understanding NP-PC interactions is crucial for optimizing NP design for biomedical applications. Traditional approaches have utilized hydrophilic polymer coatings like polyethylene glycol (PEG) to resist protein adsorption, but glycopolymer-coated nanoparticles have emerged as potential alternatives due to their biocompatibility and ability to reduce the adsorption of highly immunogenic proteins. In this study, we synthesized and characterized glycopolymer-based poly[2-(diisopropylamino)ethyl methacrylate-b-poly(methacrylamidoglucopyranose) (PDPA-b-PMAG) NPs as an alternative to PEGylated NPs. We characterized the polymers using a range of techniques to establish their molecular weight and chemical composition. PMAG and PEG-based NPs showed equivalent physicochemical properties with sizes of ∼100 nm, spherical morphology, and neutral surface charges. We next assessed the magnitude of protein adsorption on both NPs and catalogued the identity of the adsorbed proteins using mass spectrometry-based techniques. The PMAG NPs were found to adsorb fewer proteins in vitro as well as fewer immunogenic proteins such as Immunoglobulins and Complement proteins. Flow cytometry and confocal microscopy were employed to examine cellular uptake in RAW 264.7 macrophages and MDA-MB-231 tumor cells, where PMAG NPs showed higher uptake into tumor cells over macrophages. In vivo studies in BALB/c mice with orthotopic 4T1 breast cancer xenografts showed that PMAG NPs exhibited prolonged circulation times and enhanced tumor accumulation compared to PEGylated NPs. The biodistribution analysis also revealed greater selectivity for tumor tissue over the liver for PMAG NPs. These findings highlight the potential of glycopolymeric NPs to improve tumor targeting and reduce macrophage uptake compared to PEGylated NPs, offering significant advancements in cancer nanomedicine and immunotherapy.

Protein Binding Leads to Reduced Stability and Solvated Disorder in the Polystyrene Nanoparticle Corona.

Understanding the conformation of proteins in the nanoparticle corona has important implications in how organisms respond to nanoparticle-based drugs. These proteins coat the nanoparticle surface, and their properties will influence the nanoparticle's interaction with cell targets and the immune system. While some coronas are thought to be disordered, two key unanswered questions are the degree of disorder and solvent accessibility. Here, using a comprehensive thermodynamic approach, along with supporting spectroscopic experiments, we develop a model for protein corona disorder in polystyrene nanoparticles of varying size. For two different proteins, we find that binding affinity decreases as nanoparticle size increases. The stoichiometry of binding, along with changes in the hydrodynamic size, support a highly solvated, disordered protein corona anchored at a small number of enthalpically-driven attachment sites. The scaling of the stoichiometry vs. nanoparticle size is consistent disordered polymer dimensions. Moreover, we find that proteins are destabilized less severely in the presence of larger nanoparticles, and this is supported by measurements of hydrophobic exposure, which becomes less pronounced at lower curvatures. Our observations hold for flat polystyrene surfaces, which, when controlled for total surface area, have the lowest hydrophobic exposure of all systems. Our model provides an explanation for previous observations of increased amyloid fibrillation rates in the presence of larger nanoparticles, and it may rationalize how cell receptors can recognize protein disorder in therapeutic nanoparticles.