Nanoparticles (NPs) have become an important topic in colloid and materials science with diverse applications in energy, the environment and bioengineering.^1–5  A particle with spatially core–shell architecture on a nanoscopic length scale is an engrossing subject by virtue of the fascinating improved physical/chemical properties over its single-component counterpart.^6–9  Huge interest has been elicited in the usage of core–shell NPs in drug delivery,¹⁰  catalysis,¹¹  sensors,¹²  etc. Being partitioned in space, the core and the shell can perform independent or complementary functions. The two divisions are both interfaced and molecularly permeable to build molecular interactions between them, i.e., one side is able to affect the other.^13,14  For example, a hydrophilic shell not only provides different surface functional groups, but also protects the core from environmental corrosion. The core, on the other hand, can endow appropriate mechanical functionality (e.g., hard or soft) or particular properties (e.g., physical or biological), making the whole NPs effective in practical applications.