Macrocrowding of Polyethylene Glycol Facilitates the Formation of Polydopamine Nanoparticles and Derivatives via Depletion Stabilization

Mussel-inspired polydopamine nanoparticles (PDA NPs) show promise in biosensing, drug delivery, and energy storage. However, it is still difficult to obtain monodispersed PDA NPs and metal-containing PDA NPs in mild aqueous conditions. Herein, we report a facile strategy to modulate the growth and formation of PDA NPs in a macrocrowding condition using inert polymers as crowders. Our results show that both high concentrations and molecular weights are important for polymer-enabled particle stabilization. Importantly, we demonstrate that only polyethylene glycol (PEG) with a weak interaction with PDA could facilitate NPs formation. Lastly, we show that this strategy could be extended to metal-containing PDA derivatives, and enzyme-encapsulated PDA NPs. Overall, our findings offer a simple and effective approach for producing uniform biocompatible nanomaterials, while also shedding light on the role of depletion forces in nanoparticle stabilization.