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

Abstract 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.