Structure and stability of biodegradable polymer nanoparticles in electrolyte solution

The structure and stability of biodegradable hydrophobic [Poly(lactic-co-glycolic acid) (PLGA)] and amphiphilic [Poly(ethylene glycol) methyl ether-block-poly(L-lactide-co-glycolide) (PEG-PLGA)] polymer nanoparticles in aqueous electrolyte solution have been investigated by small-angle neutron scattering (SANS), dynamic light scattering (DLS), and zeta-potential measurements. The results show that PLGA forms stable, spherical nanoparticles (size similar to 90 nm, zeta similar to -50 mV) in the aqueous solution. The stability of PLGA nanoparticles rapidly decreases in the presence of NaCl, leading to the formation of micron-sized aggregates even at low salt concentrations (similar to 50 mM), because of the suppression of the stabilizing electrostatic repulsion in the presence of salt. However, the presence of NaCl even at high concentrations (similar to 500 mM) is unable to destabilize the spherical PEG-PLGA nanoparticles (size similar to 35 nm, zeta similar to -15 mV), mostly due to the additional steric repulsion barrier of hydrated PEG shell around the PLGA core, preventing nanoparticles aggregation. Such high stability of PEG-PLGA nanoparticles could be useful for ultra-small nanocarriers (sub-40 nm) applications like deep penetration in tumor tissues, etc. (C) 2021 The Authors. Published by Elsevier B.V.

Automated summary

The structure and stability of biodegradable hydrophobic (PLGA) and amphiphilic (PEG-PLGA) polymer nanoparticles in aqueous electrolyte solution were investigated. It was found that the stability of PLGA nanoparticles decreases rapidly in the presence of NaCl, leading to aggregation, while PEG-PLGA nanoparticles remained stable due to the additional steric repulsion barrier provided by the hydrated PEG shell. This high stability of PEG-PLGA nanoparticles could be beneficial for applications such as deep penetration in tumor tissues.