Gadolinium oxide: Exclusive selectivity and sensitivity in the enrichment of phosphorylated biomolecules.

ABSTRACT

Selectivity and sensitivity define the dynamic applicability of separation and enrichment techniques. Owing to proteome complexity, numbers of separation media have been introduced in phosphoproteomics. Complex samples are pretreated to make the low-abundance molecules detectable by mass spectrometry. Gadolinium oxide nanoparticles, offering mono- and bi-dentate interactions, are optimized to capture the phosphopeptides. Selectivity of 111 000 is achieved for digested ß-casein phosphopeptides in bovine serum albumin digest background using gadolinium oxide nanoparticles. The limit of detection goes down to 1 attomole. With the optimized sample preparation protocol, gadolinium oxide nanoparticles enrich phosphopeptides of κ-casein (Ser148 and Ser170 ) from digested milk sample, fibrinogen alpha chain phosphopeptide (Ser609 ) along with four hydrolytic products of Ser22 -modified phosphopeptides from serum.