Evaluation of functionalized gold nanoparticles stability in a microfluidic device to mimic a biological environment.

The functionalization of gold nanoparticles (NPs) with polyethylene glycol (PEG) and folic acid improves their stability, biocompatibility, and targeting capacity, essential for biomedical applications. However, conventional characterization methods often overlook the influence of dynamic biological environments. In this study, we investigated the stability of spherical and rod-shaped gold nanoparticles (GNSs and GNRs) under both static and dynamic conditions, utilizing a microfluidic device designed to emulate a biological environment. Nanoparticles were characterized in terms of hydrodynamic size, zeta potential, and surface plasmon resonance in three distinct media: Milli-Q water, phosphate-buffered saline (PBS), and RPMI 1640 cell culture medium supplemented with 10 % fetal bovine serum. Our findings reveal that protein-rich media enhance nanoparticle stability through the formation of a protein corona, whereas PBS promotes aggregation, particularly under static conditions. Notably, GNRs exhibited higher protein adsorption and superior colloidal stability under flow conditions compared to GNSs, a behavior attributed to their anisotropic geometry and increased surface interaction dynamics. This study underscores the relevance of testing nanoparticle behavior under physiologically relevant flow conditions, providing valuable information to optimize nanoparticle design for nanomedicine.