Microfluidic one-step synthesis of a metal-organic framework for osteoarthritis therapeutic microRNAs delivery.

As a class of short non-coding ribonucleic acids (RNAs), microRNAs (miRNA) regulate gene expression in human cells and are expected to be nucleic acid drugs to regulate and treat a variety of biological processes and diseases. However, the issues with potential materials toxicity, quantity production, poor cellular uptake, and endosomal entrapment limit their further applications in clinical practice. Herein, ZIF-8, a metal-organic framework with noncytotoxic zinc (II) as the metal coordination center, was selected as miRNA delivery vector was used to prepare miR-200c-3p@ZIF-8 in one step by Y-shape microfluidic chip to achieve intracellular release with low toxicity, batch size, and efficient cellular uptake. The obtained miR-200c-3p@ZIF-8 was identified by TEM, particle size analysis, XRD, XPS, and zeta potential. Compared with the traditional hydrothermal method, the encapsulation efficiency of miR-200c-3p@ZIF-8 prepared by the microfluidic method is higher, and the particle size is more uniform and controllable. The experimental results in cellular level verified that the ZIF-8 vectors with low cytotoxicity and high miRNAs loading efficiency could significantly improve cellular uptake and endosomal escape of miRNAs, providing a robust and general strategy for nucleic acid drug delivery. As a model, the prepared miR-200c-3p@ZIF-8 is confirmed to be effective in osteoarthritis treatment.