Particle Dimension-Induced Modulation of Human Tear Protein Corona Signatures of PEGylated Gold Nanoparticles

Ocular nanomedicine is emerging as a transformative nano–biomedicine interface, enabling precision therapeutics and targeted drug delivery for advanced ophthalmic care. Tear, a complex and rapidly renewing biological fluid, dynamically alters the protein corona of ocular nanomedicines, which is essential for reliable and sustained nanodrug delivery. Herein, we investigated the impact of various dimensions (∼15.5 ± 1, ∼50 ± 2, and ∼100 ± 5 nm) of polyethylene glycol-coated gold nanoparticles (AuNPs) in modulating the human tear protein corona. Following incubation with tears, the AuNPs@TPC complexes were purified and characterized using advanced physicochemical characterizations and electrophoresis to confirm their stability, alterations in surface charge, hydrodynamic diameter, and integrity. Further, corona compositions were profiled using LC–MS/MS proteomics and bioinformatics to distinguish particle size-dependent protein enrichment patterns. Smallest AuNPs (∼15.5 ± 1 nm) showed selective enrichment of antimicrobial proteins such as lysozyme and lactotransferrin. Medium AuNPs (∼50 ± 2 nm) displayed preferential binding of antimicrobial proteins such as lysozyme and lactotransferrin, whereas the larger AuNPs (∼100 ± 5 nm) showed increased association with lipocalins, immunoglobulins, and structural keratins. Selected core tear proteins were consistently shared across all sizes tested, but quantitative differences (87 proteins on the ∼15.5 ± 1 nm, 142 proteins on the ∼50 ± 2 nm, and 118 proteins on the ∼100 ± 5 nm AuNPs) in binding affinities and pathway enrichment revealed that particle size significantly dictates ocular bioidentity. Among the tested dimensions, the ∼50 ± 2 nm AuNPs exhibited the highest protein diversity and strongest functional pathway enrichment, indicating an optimal balance between surface curvature and the available binding area that promotes cooperative protein adsorption. In contrast, the highly curved ∼15.5 nm particles restricted multivalent protein–protein interactions, while the ∼100 ± 5 nm particles demonstrated comparatively reduced adsorption efficiency per unit surface curvature. Network and pathway analyses further revealed that intermediate-sized nanoparticles supported enhanced antimicrobial and epithelial differentiation pathways, suggesting superior biological integration at the ocular interface. These findings provide a mechanistic understanding of how PEGylated AuNPs interface with the tear proteome and highlight the importance of size in designing stable, long-lasting nanocarriers for ophthalmic drug delivery. This study builds on our previous work by providing the first quantitative, size-resolved analysis of tear protein coronas, highlighting how nanoparticle dimensions dictate ocular bioidentity.