Assembly of citrate gold nanoparticles on hydrophilic monolayers

Publication year: 2016
Authors: Vikholm-Lundin I. a, b, Rosqvist E. c, Ihalainen P. c, Munter T. d, Honkimaa A. e, Marjomäki V. f, Albers W.M. g, Peltonen J. c

a - University of Tampere, BioMediTech, Tampere, Finland
b - Fimlab Laboratories Ltd., Tampere, Finland
c - Abo Akademi University, Center for Functional Materials, Laboratory of Physical Chemistry, Finland
d - VTT Technical Research Centre of Finland, Process Chemistry end Environmental Engineering, Tampere, Finland
e - University of Tampere, Department of Virology, School of Medicine, Tampere, Finland
f - University of Jyväskylä, Department of Biological and Environmental Science, Nanoscience Center, Jyväskylä, Finland
g - BioNavis Oy Ltd, Tampere, Finland

Published in: Applied Surface Science, 2016, Vol. 378, p. 519–529
doi: doi:10.1016/j.apsusc.2016.03.213

Self-assembled monolayers (SAMs) as model surfaces were linked onto planar gold films thorough lipoic acid or disulfide groups. The molecules used were polyethylene glycol (EG-S-S), N-[tris-(hydroxymethyl)methyl]acrylamide polymers with and without lipoic acid (Lipa-pTHMMAA and pTHMMAA) and a lipoic acid triazine derivative (Lipa-MF). All the layers, but Lipa-MF with a primary amino group were hydroxyl terminated. The layers were characterized by contact angle measurements and atomic force microscopy, AFM. Citrate stabilized nanoparticles, AuNPs in water and phosphate buffer were allowed to assemble on the layers for 10 min and the binding was followed in real-time with surface plasmon resonance, SPR. The SPR resonance curves were observed to shift to higher angles and become increasingly damped, while also the peaks strongly broaden when large nanoparticles assembled on the surface. Both the angular shift and the damping of the curve was largest for nanoparticles assembling on the EG-S-S monolayer. High amounts of particles were also assembled on the pTHMMAA layer without the lipoic acid group, but the damping of the curve was considerably lower with a more even distribution of the particles. Topographical images confirmed that the highest number of particles were assembled on the polyethylene glycol monolayer. By increasing the interaction time more particles could be assembled on the surface.

MP-SPR keywords: adsorption, binding, gold nanoparticle, metal nanoparticle, self-assembled layer, surface chemistry