In this paper, we report an antibody functionalized microimmunopreci- pitation(μIP) method used for enrich lowabundant post-translational modified(PTM) proteins. The device is fabricated by inert, nontoxic and disposable polydimethylsiloxane(PDMS) using a silane-based chemical modification protocol, which yield antibody-terminated PDMS surfaces. In this study, the μIP device is specifically designed for the purification of carbonylated protein, a representative example here to illustrate the potential applications for any other PTMs, which could be immuno-tagged by specific antibodies. The test model in vitro oxidized bovine serum albumin(BSA) was first derivitized by dinitrophenylhydrazide(DNPH) and then captured by the anti-DNP immobilized on this μIP device. The surface functional group mapping was systematically analyzed and validated by fluorescence microscopy. Quantitative study of DNP-derivatized carbonylated protein capture recovery and elution efficiency of the device was also studied. We also envision that this proteome enrichment μIP device can be assembled with other lab-on-a-chip components, such as microelectrophoresis or micro-chromatographic devices for follow-up protein analysis. This selective enrichment of modified proteins greatly facilitates the study of low abundant protein biomarkers discovery.
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