Preparation of titanium (IV) immobilized core-shell magnetic covalent organic framework nanospheres for highly selective enrichment of nucleotides from human serum

In this work, a titanium (IV) immobilized covalent organic framework (COF) was developed and used as an efficient adsorbent for highly selective enrichment of nucleotides from human serum. Firstly, an amino-functionalized magnetic COF (Fe3O4@TpBD(NH2)2) was synthesized by the in situ growth strategy. Alendronate sodium (AS) was then modified on the surface of the Fe3O4@TpBD(NH2)2 via Schiff base reaction. Finally, Ti4+ was chelated to obtain immobilized metal ion affinity chromatography (IMAC) adsorbent (denoted as Fe3O4@COF-AS-Ti4+). Its adsorption performances toward nucleotides including adenosine triphosphate (ATP), adenosine-5′-diphosphate (ADP) and adenosine-5′-monophosphate (AMP) were investigated, their maximum adsorption capacity were 36.7, 39.0 and 49.6 μmol/g, respectively. The adsorption and desorption can be achieved very fast (in 1 min). In addition, the Fe3O4@COF-AS-Ti4+ can still selectively adsorb nucleotides in the presence of other analogues, such as nucleosides, phenols, aromatic amines and phenol amines. It can be served as a good adsorbent for selective enrichment of nucleotides and simultaneous exclusion of biomacromolecules. It has also good synthesis reproducibility and reusability. These features suggest that the Fe3O4@COF-AS-Ti4+ nanospheres are of great benefit for pretreatment prior to instrument analysis of nucleotides.