Heparin-Binding Proteins in the Nanoparticle Corona Enhance Cellular Uptake through Glycocalyx Interactions

Nanoparticles (NPs) designed for intracellular delivery must first navigate the cell-surface glycocalyx before reaching the plasma membrane for internalization. Here, we hypothesized that the glycocalyx can both hinder NP uptake via a barrier effect and enhance uptake by providing recognition sites for corona proteins. To dissect these opposing mechanisms, we prepared NPs with plasma protein coronas either enriched or depleted in heparin-binding proteins (HBPs), along with model coronas containing selected HBPs or non-HBPs. Biophysical assays confirmed strong heparin interactions for HBP-rich NPs, whereas HBP-poor NPs showed weak or no binding. To assess the role of corona-glycocalyx interactions in NP uptake, we used glycocalyx-depleted cells, a chemical inhibitor, and heparin and antithrombin competition assays. We found that canonical HBPs within the protein corona, including antithrombin, apolipoprotein E, and platelet factor 4, significantly enhanced NP surface retention and internalization through protein-glycocalyx interactions. In contrast, HBP-poor NPs showed weak or no interactions with the glycocalyx and, correspondingly, reduced uptake. Significantly, these findings also extended to physiologically derived coronas from control and dyslipidemic sera, with the latter producing HBP-enriched coronas that bound more strongly to heparin and promoted more efficient glycocalyx-dependent NP uptake. These findings highlight the underappreciated role of the glycocalyx in actively engaging with coronal HBPs to drive efficient NP uptake. This insight underscores the need to expand corona engineering beyond membrane receptor interactions, incorporating strategies that optimize glycocalyx interactions for more effective NP delivery.