Microfluidic synthesis of metal-organic framework crystals with surface defects for enhanced molecular loading

• Control of surface defects of HKUST-1 microcrystals through the continuous flow synthesis in a microfluidic chip. • Well-developed MOF surface defects enhance dye molecules loading and release via laser irradiation. • Biocompatibility and uptake of HKUST-1 microcrystals by murine melanoma cells. Inherent properties of metal-organic frameworks (MOFs) such as porosity and chemical diversity allows utilizing them as drug delivery systems which are not toxic at 25 MOFs per B16-F10 cell. Herein, the MOF developed surface due to intrinsic defects enables exploration of a new form of efficient delivery with remote control. Here we experimentally demonstrate the directed synthesis of MOF microcrystals (HKUST-1) with developed surface defects by a single-step microfluidics method. The synthesis process has been optimized to obtain the desired MOFs that ensure the enhanced loading of molecules (fluorescence dye) on their surface as compared with MOFs synthesized by solvothermal approach. Structural analysis and optical spectroscopy confirmed the defective MOF surface. Dye loading and remote light-induced release has been demonstrated under continuous wave laser irradiation (532 nm). Toxicity of the obtained MOFs and their interaction with murine melanoma cells have been additionally tested. Therefore, the ability to design and synthesize MOFs with the desired physicochemical properties and 2 times higher loading capacities than a solvothermally synthesized one due to the use of microfluidic approach opens up new prospects for the development of improved drug delivery platforms.