Microwave and Polymer-Assisted Synthesis of Ultrasmall Polydopamine Nanoparticles: Applications as Support for...

Tuning the size of nanomaterials is a critical factor to consider when designing and optimizing their applications. In this context, polydopamine nanoparticles have demonstrated potential across a wide range of biomedical applications (Battaglini, M.; Emanet, M.; Carmignani, A.; Ciofani, G. Nano Today 2024, 55, 102151). However, achieving ultrasmall sizes remains a significant challenge, as most reported diameters in the literature exceed 50 nm. In this study, we present a method for synthesizing ultrasmall polydopamine nanoparticles (sPDA) with diameters below 5 nm. This is accomplished by employing a capping agent, polyvinylpyrrolidone, in combination with ultrafast microwave-assisted heating under basic pH conditions. Furthermore, we investigate the affinity of the synthesized sPDA nanostructures for various metal ions and observe excellent binding to iron ions. This property opens new avenues for catalytic applications and intracellular iron delivery, surpassing the performance of conventional polydopamine nanoparticles.