A composite consisting of a deep eutectic solvent and dispersed magnetic metal-organic framework (type UiO-66-NH₂)...

A cactus-shaped magnetic composite was prepared for solid-phase extraction of RNA. It is composed of the metal organic framework UiO-66-NH₂ that was modified with Fe₃O₄ nanoparticles. The composite was then dispersed in a lactic acid-based deep eutectic solvent (DES, Fe₃O₄-COOH@UiO-66-NH₂@DES). The structures of the sorbents were characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectrometry, vibrating sample magnetometry and thermogravimetric analysis. The extraction performance of sorbents was optimized and the maximum extraction capacity reached 246 mg·g^-1. Extraction is shown to mainly rely on chelation interaction, electrostatic interaction, hydrophobic interaction and hydrogen bonding interaction. The sorbent can selectively extract RNA over DNA, bovine hemoglobin and amino acids. Regeneration studies indicated that the sorbent can be re-used (after regenreation with DES) several times without obvious change of the extraction capacity. The successful extraction of RNA from yeast testified the practical application of the sorbent. Graphical abstractSchematic representation of the fabrication Fe₃O₄-COOH@UiO-66-NH₂@DES, and its application in the magnetic solid phase extraction of RNA.