Temperature‐Regulated Core Swelling and Asymmetric Shrinkage for Tunable Yolk@Shell Polydopamine@Mesoporous Silica Nanostructures

Abstract Facile and controllable synthesis of functional yolk@shell structured nanospheres with a tunable inner core (‘yolk') and mesoporous shell is highly desirable, yet it remains a great challenge. Herein, xx developed a strategy based on temperature‐regulated swelling and restricted asymmetric shrinkage of polydopamine (PDA) nanospheres, combined with heterogeneous interface self‐assembly growth. This method allows a simple and versatile preparation of PDA@mesoporous silica (MS) nanospheres exhibiting tunable yolk@shell architectures and shell pore sizes. Through reaction temperature‐regulated swelling degree and confined shrinkage of PDA nanospheres, the volume ratio of the hollow cavity that the PDA core occupies can easily be tuned from ca. 2/3 to ca. 1/2, then to ca. 2/5, finally to ca. 1/3. Owing to the presence of PDA with excellent photothermal conversion capacity, the PDA@MS nanocomposites with asymmetric yolk distributions can become a colloidal nanomotor propelled by near‐infrared (NIR) light. Noteworthily, the PDA@MS with half PDA yolk and microcracks in silica shell reaches 2.18 µm²s⁻¹of effective diffusion coefficient (De) in the presence of 1.0 W cm⁻²NIR light. This temperature‐controlled swelling approach may provide new insight into the design and facile preparation of functional PDA‐based yolk@shell structured nanocomposites for wide applications in biology and medicine.