Chiral separation of dansyl amino acids by PDMS microchip gel monolithic column electrochromatography with γ-cyclodextrin bonded in polyacrylamide

A polydimethylsiloxane (PDMS) microchip polyacrylamide (PAA) gel monolithic column for electrochromatography was prepared. A chiral recognizable molecule, γ-cyclodextrin (γ-CD) was immobilized firmly in the PAA gel in the microchannel through chemical bond. The PDMS microchannel was pretreated with 3-(trimethoxysilyl)-propyl methacrylate (Bind-Silane) before bonding PAA monolithic column, which was an anchor molecule to connect the PAA gel with PDMS inner wall in microchannel. The experiments demonstrated γ-CD was a perfect chiral selector for fluorescein isoihiocyanate (FITC) labeled dansyl amino acids (Dns-AAs), which showed well capability for chiral recognization in monolithic column electrochromatography. The mixture of two pairs of FITC-labeled Dns-AAs was separated absolutely in this new-style PDMS-based microfluidic device monolithic column within 100 s in 36 mm effective separation length, and the resolutions of the two pairs of optical isomers could reach 2.53 and 1.12, respectively. The condition of preparation PAA gel monolithic column for chiral separation was optimized by adjusting the concentration of allyl-γ-CD. The stability, transferring heat and optical characteristic of PDMS-based microfluidic device monolithic column were examined, respectively.