*4.2.1.1.1 Capping agent-assisted synthesis (CAAS)*

First of all, the pre-synthesized core materials and capping agents/surfactants like PVP which is an amphiphilic nonionic polymer, are simultaneously provided earlier the growth of MOF shell around them due to prevent the aggregation of active NPs and/or the self-nucleation of MOF particles [53]. In addition, capping agents intensify the compatibility between the MNPs and the MOF shell. While PVP is the most popular capping agent for encapsulation of inorganic materials in MOFs, depending on the design process of core materials can be utilized the other type of surfactants like cetyltrimethylammonium bromide (CTAB), tetradecyltrimethylammonium bromide (TTAB), cetylpyridinium bromide (CPB), and sodium dodecyl sulfate (SDS). The CTAB is the optimal surfactant in terms of shape/overgrowth control, as well as PVP, owing to the sizes and shapes of the final composite can be adjusted by changing the growth time and the quantity of CTAB in solution. Overall, despite CAAS being a popular method due to the ability to control the shape, size, and chemical nature of the encapsulated core, the multiple steps of this method restricted its utilization [53].
