Tailoring of a TiO2 nanotube array-integrated portable microdevice for efficient on-chip enrichment and isotope labeling of serum phosphopeptides.

Herein we present a gravity-driven microdevice furnished with tunable TiO2 nanotube arrays (TNAs) inside as the separation medium for consecutive on-chip enrichment and isotope labeling of serum phosphopeptides. The 3D tubular architectures of TNAs dramatically enhanced the affinity towards phosphate-containing molecules and also provided a spacious microenvironment for isotope dimethyl labeling reactions. To maximize the efficiency and capacity of the phosphopeptide enrichment, nanoscale tailoring and microscale fabrication were employed for adjusting the TNAs' pore sizes and the channel patterns. The S-shaped microdevice equipped with interior TNAs anodized at 25 V was utilised for consecutive serum processing, and further differential expression analysis of endogenous phosphopeptides between ovarian cancer patients and healthy women. The phosphorylated fibrinogen peptide A (FPA, AD[pS]GEGDFLAEGGGVR) was found to be down-regulated by about 4 times while its isoform (D[pS]GEGDFLAEGGGV) was 2.4-fold up-regulated in the patient specimens. In principle, this nanostructure-embedded model introduced tailor-made bioseparation materials into the microdevice, undoubtedly facilitating the workflow of sample pretreatment and thus assisting the analysis of disease-associated biomolecules in biomedical research.