Multi-Functional Polydopamine-Mucin Hollow Particles Provide Tunable Shell Permeability, ROS Scavenging, Tissue Adhesion, and Lubricity for Biomedical Applications.

Owing to their high drug loading capacity and the option to functionalize their shells, hollow particles (HPs) have emerged as versatile platforms for diagnostic and therapeutic applications. However, those two key advantages of HPs are not yet well leveraged. Often, the large volume within the shells is not fully utilized as a consequence of the employed drug loading methods, and to date, only a limited range of functionalities can be successfully implemented into the shells of HPs. Here, the self-polymerization and adhesion behavior of dopamine are utilized, for the first time, to fabricate polydopamine (PDA)-mucin HPs using a template-based method. By adopting molecules or ions as "locks" to adjust the permeability of the shells, cargo molecules can be trapped within the shells with high encapsulation efficiency. Moreover, owing to the intrinsic properties of PDA and mucins, the shells exhibit multiple functionalities in vitro and ex vivo, including free radical scavenging, tissue adhesion, lubrication, and wear prevention. This study presents a facile method to produce multi-functional PDA-based HPs from a range of (bio)polymers, thus facilitating potential applications of HPs for the treatment of certain diseases, including osteoarthritis and mouth ulcers.