Facile preparation of protein stationary phase based on polydopamine/graphene oxide platform for chip-based open tubular capillary electrochromatography enantioseparation
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Abstract
A novel chip-based enantioselective open-tubular capillary electrochromatography (OT-CEC)
was developed employing bovine serum albumin (BSA) conjugated polydopamine-graphene
oxide (PDA/GO) nanocomposites (PDA/GO/BSA) as stationary phase. After the poly(dimethylsiloxane)
(PDMS) microfluidic chip was filled with a freshly prepared solution containing dopamine
and graphene oxide, PDA/GO nanocomposites were formed and deposited on the inner wall
of microchannel as permanent coating via the oxidation of dopamine by the oxygen dissolved
in the solution. The PDA/GO-coated PDMS microchips not only have the adhesion of PDA
that make them easily immobilized in the microchannel, but also have the larger surface
and excellent biocompatibility of graphene which can incorporate much more biomolecules
and well maintain their biological activity. In addition, incorporation of GO in PDA
film can make surface morphology more rough, which is beneficial for enhancing the
loading capacity of proteins in the microchannels and increasing sample capacity of
OT-CEC columns. BSA was stably immobilized in the PDMS microchannel to fabricate a
protein-stationary phase. Compared with the native PDMS microchannels, the modified
surfaces exhibited much better wettability, more stable electroosmotic mobility, and
less nonspecific adsorption. The efficient separation of chiral amino acids (tryptophan
and threonine) and chiral dipeptide demonstrate that the constructed OT-CEC columns
own ideal enantioselectivity. The presented strategy using PDA/GO coating as a versatile
platform for facile conjugation of proteins may offer new processing strategies to
prepare a functional surface designed on microfluidic chips.