title: Porous polymer monolithic columns with gold nanoparticles as an intermediate ligand for the separation of proteins in reverse phase-ion exchange mixed mode.
abstract: A new approach has been developed for the preparation of mixed-mode stationary phases to separate proteins. The pore surface of monolithic poly(glycidyl methacrylate-co-ethylene dimethacrylate) capillary columns was functionalized with thiols and coated with gold nanoparticles. The final mixed mode surface chemistry was formed by attaching, in a single step, alkanethiols, mercaptoalkanoic acids, and their mixtures on the free surface of attached gold nanoparticles. Use of these mixtures allowed fine tuning of the hydrophobic/hydrophilic balance. The amount of attached gold nanoparticles according to thermal gravimetric analysis was 44.8 wt.%. This value together with results of frontal elution enabled calculation of surface coverage with the alkanethiol and mercaptoalkanoic acid ligands. Interestingly, alkanethiols coverage in a range of 4.46-4.51 molecules/nm(2) significantly exceeded that of mercaptoalkanoic acids with 2.39-2.45 molecules/nm(2). The mixed mode character of these monolithic stationary phases was for the first time demonstrated in the separations of proteins that could be achieved in the same column using gradient elution conditions typical of reverse phase (using gradient of acetonitrile in water) and ion exchange chromatographic modes (applying gradient of salt in water), respectively.
authors.affiliation: The Molecular Foundry, E.O. Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States.
authors.forename: Lydia
authors.initials: L
authors.lastname: Terborg
authors.affiliation: Institute of Chemistry, Department of Fundamental Chemistry, University of São Paolo, C.P. 26077, 05513-970 São Paulo, Brazil.
authors.forename: Jorge C
authors.initials: JC
authors.lastname: Masini
authors.affiliation: Department of Chemistry, University of California, Berkeley, CA 94720, United States.
authors.forename: Michelle
authors.initials: M
authors.lastname: Lin
authors.affiliation: Laboratory of Analytical Chemistry, Department of Chemistry, P.O. Box 55, FIN-00014, University of Helsinki, Helsinki, Finland.
authors.forename: Katriina
authors.initials: K
authors.lastname: Lipponen
authors.affiliation: Laboratory of Analytical Chemistry, Department of Chemistry, P.O. Box 55, FIN-00014, University of Helsinki, Helsinki, Finland.
authors.forename: Marja-Liisa
authors.initials: ML
authors.lastname: Riekolla
authors.affiliation: The Molecular Foundry, E.O. Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States.
authors.forename: Frantisek
authors.initials: F
authors.lastname: Svec
keywords: Gold nanoparticles; Mixed mode; Monolith; Proteins; Separation