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    Adsorption of Cationic Hydroxyethylcellulose Derivatives onto Planar and Curved Gold Surfaces

    Year: 2010

    Journal: Langmuir, 2010, 26 (20), pp 15925–15932, 20101201

    Authors: Pamies R. †‡, Volden S. §, Kjøniksen A-L †, Zhu K. †, Glomm W.R. §, Nyström B. *†

    Last authors: Bo Nyström

    Organizations: † Department of Chemistry, University of Oslo, P.O. Box 1033, N-0315 Oslo, Norway ‡ Department of Physical Chemistry, Faculty of Chemistry, University of Murcia, 30071 Murcia, Spain § Ugelstad Laboratory, Department of Chemical Engineering, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway Department of Pharmaceutics, School of Pharmacy, University of Oslo, P.O. Box 1068, Blindern, N-0316 Oslo, Norway

    Country: Norway

    The adsorption of two positively charged hydroxyethylcellulose derivatives with 7 and 60 mol % positively charged groups and a cationic, hydrophobically modified hydroxyethylcellulose containing 1 mol % hydrophobic groups and 7 mol % charged groups onto flat and spherical citrate-coated gold surfaces of different sizes has been investigated. The planar surfaces were studied by means of the quartz crystal microbalance with dissipation monitoring, whereas nanoparticle suspensions were examined using dynamic light scattering and UV−vis spectroscopy. Two different driving forces for adsorption have been evaluated: the electrostatic interaction between the positive charges on the polymers and the negatively charged gold surfaces and the affinity of the polymers for gold due to hydrophobic interactions. The comparison between the data obtained from curved and planar surfaces suggests a strong correlation between surface curvature and adlayer conformation in the formation of the hybrid polymer−gold nanoparticles. The influence of particle size on the amount of adsorbed polymer has been evaluated for the different polymers. The impact of the ionic strength on polymer adsorption has been explored, and the adsorbed polymer layer has been found to protect the gold nanoparticles from aggregation when salt is added to the solution. The addition of salt to a mixture of gold particles and a charged polymer can induce a thicker adsorbed layer at low salinity, and desorption was found at high levels of salt addition.