Preparation Of Hyperbranched Polymer Modified Molecular Imprinting Polymer And Its Application In PDMS Microfluidic Chips

In this research, many technologys were mixed, such as hyperbranched polymer,microfluidic chip technology and molecular Imprinting Technology, in order to separation thechiral amino acid. A brand new molecular imprinting polymer (MIPS), which was modifiedby hyperbranched polymer, was synthesized to graft to the surface of PDMS micro channelsfor the separation of L-tryptophan and R-tryptophan.The research content mainly includes the following aspects:(1)Synthesis and characterization of hyperbranched polyaminoesterFirst, AB2-type monomer was synthesized by acrylic acid and diethanolamine. Then,different generations hyperbranched polyaminoester was obtained via changing of the ratioAB2monomer between core molecule. IR, TGA, hydroxyl value measurement and viscosityanalysis were employed to characterize the structure and property of hyperbranchedpolyaminoester. The result showed that the hyperbranched polyaminoester, which has a largenumber of terminal hydroxyls, low viscosity and good thermal stability, was synthetizedsuccessfully.(2)Synthesis of L-tryptophan MIPThe hyperbranched polyaminoester was modified by acrylic acid. The result of IR andhydroxyl value measurement shows that the hyperbranched polyaminoester after modificationpossess mass hydroxyls and C=C bonds. The L-tryptophan MIP modified by hyperbranchedpolymer was synthesized via the copolymerization of L-tryptophan as template molecule,meth acrylic acid as functional monomer AIBN as initiator and EGDMA as cross-linker. Theadsorption curves and elution curves shows that modified MIP has stronger adsorption andlonger elution time than original MIP.(3) Surface modification of PDMS microfluidic chipsThe MIP modified by hyperbranched polymer was grafted to the surface of microchannels via chemical bonding. The contact angle of the different chips was measured. Theresult showed that the contact angle of original chips was108°. After modification, the contact angle decreased to84°. The hydrophilicity of the chip surface has been improved. Thesurface morphology of modified chips was observed using SEM. The surface of microchannels was grafted by abundant and compact MIPs.(4)Separation of the chiral amino acid using PDMS microfluidic chips after modificationAt first, the optimal detection conditions were established. The optimal separationconditions are as follows: phosphate buffer concentration40mmol/L, pH5.0, separationvoltage8kV and detection wavelength214nm. The result showed that the original PDMSchips could not separate L-tryptophan and R-tryptophan. Compared with original chips, theMIP modified chips got some improvement in the separation. But the two detection peaksobtained were not separated completely. G2-PDMS succeed in the chiral separation oftryptophan in10min. Although G3-PDMS also separated the two kinds of amino acid, it tookmuch more time nearly13min.