In-situ growth of boronic acid-decorated metal-organic framework on Fe3O4 nanospheres for specific enrichment of cis-diol containing nucleosides

In this study, a novel core-shell structured magnetic metal-organic framework nanospheres (Fe3O4@PD@BA-Zr-MOF) were fabricated by in-situ growth of boronic acid-decorated porphyrin-based metal-organic frameworks on polydopamine (PD) functionalized Fe3O4 nanospheres for highly efficient enrichment of cis-diol containing nucleosides by magnetic solid phase extraction (MSPE). PD as a molecular linker promotes the nucleation and crystal growth of boronic acid-decorated porphyrin-based metal-organic framework (BA-Zr-MOF), which was synthesized via a dual-ligand strategy by using Zr4+ as a metal unit as well as meso-tetra (4-carboxylphenyl) porphyrin (TCPP) and 1, 4-phenylenebisboronic acid (BA) as dual organic ligands. It is worth noting that the nitrogen-rich skeleton of TCPP and abundant boric acid groups in MOF allows for effective and selective enrichment of cis-diol containing compounds by hydrophilic interaction and boron affinity. Also, Zr4+ well assembled into the MOF is beneficial to extraction via metal oxide affinity interaction due to reversible covalent complex formation/dissociation between Zr and cis-diol compounds. The morphology, structure and saturation magnetization of Fe3O4@PD@BA-Zr-MOF were systematically characterized. The as-prepared adsorbent coupled with high performance liquid chromatography was used for analysis of four nucleosides including cytidine, uridine, guanosine, and adenosine in urine sample with the detection limits in range of 0.002-0.005 μg mL-1 and the quantitative limits in range of 0.008-0.018 μg mL-1. The as-fabricated Fe3O4@PD@BA-Zr-MOF nanospheres shows high selectivity, low detection limit, excellent reusability and reproducibility for nucleosides enrichment. The large specific surface area and quick magnetic response performance endow the affinity magnetic nanospheres with outstanding enrichment capability for rapid extraction. The adsorbent of Fe3O4@PD@BA-Zr-MOF nanospheres has great potential for identification and analysis of trace cis-diol containing nucleosides in biological samples.