Effect of solvation on the synthesis of MOFs-based micro/nanorobots and its targeted-therapy applications

Magnetically driven mobile micro/nanorobots have a significant influence on the application and development of intelligent targeted drug delivery. However, the potential risk of biological toxicity is one of the major problems in drug-loaded micro/nanorobot fabrication. Therefore, there is an urgent need to combine the features (high cargo-loading, low biotoxicity, and good biodegradability) of metal–organic frameworks (MOFs) with micro/nanorobot mobility. In this paper, the concept of green chemical synthesis is used to prepare mass-manufactured biodegradable MOF-based microrobots with low biotoxicity and high drug loading for the targeted treatment of cancer cells. Based on the solvation principle of the binary solvent system, the two-component solvent will be mixed with aprotic polar solvents (X = DMAC, DMF, DMSO, NMP) and proton polar solvents (MeOH) to reduce original aprotic polar solvent toxicity. This can adjust the electrophilicity and polarity of the solution environment, change the configuration of organic ligands, and directly affect the nucleation and growth of MOF crystallites. The results show that five different MOF crystal structures can be synthesized on the surface of microrobots. The MOFs synthesized in a DMAC/MeOH solvent system have cubic structures with good biocompatibility and drug delivery properties. Furthermore, the magnetically actuated motion of MOF-based microrobots with different geometries was systematically tested to obtain the best swimming performance. Subsequently, the microrobots were guided through vascular-like microfluidic channels and can be precisely controlled. Thus, this establishes a foundation to create mass-manufactured microrobotic systems that provide a new direction for small-scale medical robots with low toxicity, high drug loading capacity, biodegradability, and precise motion control.