Formation of positively charged gold nanoparticle monolayers on silica sensors

Magdalena Oćwieja; Julia Maciejewska-Prończuk; Zbigniew Adamczyk; Maciej Roman

doi:10.1016/j.jcis.2017.04.038

Formation of positively charged gold nanoparticle monolayers on silica sensors

J Colloid Interface Sci. 2017 Sep 1:501:192-201. doi: 10.1016/j.jcis.2017.04.038. Epub 2017 Apr 13.

Authors

Magdalena Oćwieja¹, Julia Maciejewska-Prończuk², Zbigniew Adamczyk³, Maciej Roman⁴

Affiliations

¹ Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland. Electronic address: ncocwiej@cyf-kr.edu.pl.
² Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland. Electronic address: ncmaciej@cyf-kr.edu.pl.
³ Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland. Electronic address: ncadamcz@cyf-kr.edu.pl.
⁴ Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, PL-31342 Krakow, Poland. Electronic address: Maciej.Roman@ifj.edu.pl.

PMID: 28456103
DOI: 10.1016/j.jcis.2017.04.038

Abstract

Formation of positively charged gold nanoparticle monolayers on the Si/SiO₂ was studied under in situ conditions using quartz microbalance (QCM). The gold nanoparticles were synthesized in a chemical reduction method using sodium borohydride as reducing agent. Cysteamine hydrochloride was applied to generate a positive surface charge of nanoparticles. The micrographs obtained from transmission electron microscopy (TEM) revealed that the average size of nanoparticles was equal to 12±3nm. The stability of nanoparticle suspensions under controlled pH and ionic strength was determined by dynamic light scattering (DLS). The electrophoretic mobility measurements showed that the zeta potential of nanoparticles was positive, decreasing with ionic strength and pH from 56mV at pH 4.2 and I=10^-4M to 22mV at pH 8.3 and I=3×10^-3M. The surface enhanced Raman spectroscopy (SERS) confirmed chemisorption of cysteamine on nanoparticles and the contribution of amine moieties in the generation of nanoparticle charge. The influence of suspension concentration, ionic strength and flow rate on the kinetics of nanoparticle deposition on the sensors was quantitatively determined. It was confirmed that the deposition for the low coverage regime is governed by the bulk mass transfer that results in a linear increase of the coverage with time. The significant increase in the maximum coverage of gold monolayers with ionic strength was interpreted as due to the decreasing range of the electrostatic interactions among deposited particles. Moreover, the hydratation of formed monolayers, their structure and the stability were determined by the comparison of the QCM results with those obtained by AFM and SEM. The experimental data were adequately interpreted in terms of the extended random sequential adsorption (eRSA) model that considers the bulk and surface transfer steps in a rigorous way. The obtained results are useful for a facile fabrication of gold nanoparticle-based biosensors capable to bind target molecules via available amine moieties.

Keywords: Cysteamine-stabilized nanoparticles; Flow-controlled deposition; Formation of colloid monolayer; Monolayers of positively charged nanoparticles; Positively charged gold nanoparticles.