"Old" metal oxide affinity chromatography as "novel" strategy for specific capture of cis-diol-containing compounds.

The metal oxide affinity chromatography (MOAC) materials have been extensively used for extraction of phosphate compounds in the past decade. Actually, some of these materials also possess adsorption affinity towards cis-diol-containing compounds, which was seldom explored in separation field so far. Here we present the proof-of-concept study to evaluate the feasibility of expanding MOAC for specific capture of cis-diol biomolecules. Benefitting from the high commercialisation of the metal oxide materials, such MOAC strategy possesses several advantages, like synthesis-free, low cost and high expandability. Firstly, the recognition of adenosine against 2'-deoxyadenosine was performed using zirconium oxide and cerium oxide, two typical commercial MOAC materials. The results showed that efficient adsorption and elution could be achieved easily by pH switching from basic to acidic. The isotherm curves demonstrated the adsorption process fitted well with Freundlich isotherm model and was spontaneous at room temperature (ΔG(0)<0) with an exothermic nature (ΔH(0)<0). Afterwards, the highly efficient and selective enrichment of various model cis-diol biomolecules, including ribonucleosides, glycopeptides and glycoproteins, was achieved using this MOAC strategy. Finally, the endogenous ribonucleosides and modified ribonucleosides were successfully purified from human urine sample, which demonstrated the potential application of MOAC materials in the enrichment of target compounds from complex biological samples. Besides the excellent performance of extraction for cis-diol-containing compounds, equally important is that these materials are commercially available with low cost, which makes the MOAC a promising strategy for the study of cis-diol biomolecules in metabolomics and proteomics.