Hybrid Assembled Colloids with Controllable Core–Satellite Structure for pH-Responsive Nanocarriers

A type of hybrid assembled colloid has been developed with a salient feature of spontaneous assembly and pH-responsive disassembly, and the fabrication is based on the formation of noncovalent conjunctions based on host–guest interactions between cinnamaldehyde and β-cyclodextrin bonding to different nanoparticle components, forming a structure with three-dimensional dendritic mesoporous silica nanospheres as core and gold nanoparticles as the satellites with tunable densities. These hybrid assembled colloids are stable under neutral pH, and disassembly of them can occur in a mildly acidic environment dependent on hydrolysis of the pH-sensitive imine bonds in the conjunctions between cinnamaldehyde and mesoporous silica nanospheres, which is independent structurally from the host–guest assembling part. These hybrid assembled colloids can serve as pH-responsive nanocarriers with a loading capacity of ∼69 wt % with doxorubicin as a model cargo of organic small molecules as well as ∼31 wt % with β-lactoglobulin as a model cargo of proteins. Leakage of both types of cargoes was prevented by blocking the pore openings of mesoporous materials with the assembled satellites under neutral pH, while their release was triggered by a mildly acidic environment. These results demonstrate that these nanocarriers constitute a general platform for the controlled released of versatile cargoes, ranging from organic small molecules with sizes below 1 nm to biomacromolecules with sizes round 5 nm, suggesting its great potential in biomedical applications.