| In recent years, microfluidic chip technology has been widely used in the field of lifescience. Polydimethylsiloxane (PDMS) microfluidic chips based on their remarkabletransmittance, non-toxic, easy processing and low cost has become one of the most usedmaterials in microfluidic chip fields. But, PDMS microfluidic chips have some defects, forexample,(1) Chips possessed strong hydrophobic surface, which could adsorb samplemolecules and resulted in poor analysis results.(2) The electroosmotic flow instability ofPDMS microfluidic chips. In order to make up for defects of PDMS microfluidic chips, there isan urgent need for methods to treat with the surface of PDMS.In this paper, hyperbranchedpolyaminoester (HPAE) consisted of multitude end hydroxy (-OH) groups and has thehydrophilic was synthesized.The purpose of the modification is to improve the hydrophilicityof chips’ surface, inhibit the adsorption of the sample molecules and thus improve the analyticalperformance of chips.The research content mainly includes the following aspects:1. Synthesis and characterization of hyperbranched polyaminoesterAB2-type monomer containing one methoxy group and two hydroxylic groups wasprepared using methyl acrylate and diisopropanolamine via michael addition reaction, thenthe hyperbranched polyaminoester was synthesized between the AB2-type monomer andtriethanolamine as a core molecule. Different generations of hyperbranched polyaminoestercan be adjusted by monomer and nuclear molecular ratio.The structure and properties of theproduct were characterized by IR, hydroxyl value measurement, elemental analysis, viscosityanalysis and TGA. The result showed that the hyperbranched polyaminoester synthsized had alarge number of terminal hydroxyl, low viscosity and good thermal stability, thus it was apromising chips modification material.2. Surface modification of PDMS microfluidic chipsThe PDMS microfluidic chips were modified using the hyperbranched polyaminoestervia chemical bonding method and physical coating method. The surface morphology ofmodified chips was observed using contact angle measurement instrument, SEM andfluorescence microscope. To determine the polymer grafted onto the chip. The electroosmotic flow and stability of hyperbranched polyaminoester coating were also investigated. The resultshowed that the surface of modified chips possessed a layer of dense, uniform coating and thechip surface from hydrophobic to hydrophilic.It was also found the hydrophilic coating wasvery stable.3. The separation and detection of organic pesticide sample by chip coating columnChip coating columns were modified by different means to separation and detection fivekinds of organic phosphorus pesticide (Dichlorvos, Malathion, Phoxim, Triazophos, Dursban)and three kinds of pesticides (Hymexazol, Thiacloprid, Triflumizole) were separated anddetected.The result showed that the unmodified chips could’t effectively separateorganophosphorus pesticide. The PDMS microfluidic chips were modified by two differentkinds of methods can successfully separated organic pesticides. The detection peaks obtainedwere separated clearly,no trailing and the shape of the peaks was sharp.4. Research on the separation performance of the modified chipsThe separation column efficiency of organic pesticide, the degree of separation, and thechip coated column stability were studied by chip coating columns which were prepared byphysical coating modification and chemical bonding modification, respectively. The resultsshow that two kinds of modified chips can obtain good separation effect. The PDMSmicrofluidic chip coating columns have achieved a complete separation of the organicpesticides and the detection peaks were clear and sharp. The modified chips had goodseparation column efficiency and resolution, stability of coated column was also good. Thisresearch provides a novel method for the separation and detection of organic pesticides. It canbe seen by the experimental data: the chemical bond modified method have better separationeffect and a longer service life. This is mainly due to chemical bonding modified method isthrough the chemical bond grafted to the surface of the chip using hyperbranchedpolyaminoester and physical coating method is through the interaction of molecules. Thesurface coating is not strong in the chip surface, but the two modified methods can achieveeffective separation of organic pesticides... |
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