Stability of silver nanoparticle monolayers determined by in situ streaming potential measurements

Abstract

A silver particle suspension obtained by a chemical reduction was used in this work. Monolayers of these particles (average size 28 nm) on mica modified by poly(allylamine hydrochloride) were produced under diffusion-controlled transport. Monolayer coverages, quantitatively determined by atomic force microscopy (AFM) and SEM, was regulated by adjusting the nanoparticle deposition time and the suspension concentration. The zeta potential of the monolayers was determined by streaming potential measurements carried out under in situ (wet) conditions. These measurements performed for various ionic strengths and pH were interpreted in terms of the three-dimensional (3D) electrokinetic model. The stability of silver monolayers was also investigated using streaming potential and the AFM methods. The decrease in the surface coverage of particles as a function of time and ionic strength varied between 10−1 and 10−4 M was investigated. This allowed one to determine the equilibrium adsorption constant Ka and the binding energy of silver particles (energy minima depth). Energy minima depth were calculated that varied between −18 kT for I = 10−1 M and −19 kT for I = 10−4 for pH 5.5 and T = 298 K. Our investigations suggest that the interactions between surface and nanoparticles are controlled by the electrostatic interactions among ion pairs. It was also shown that the in situ electrokinetic measurements are in accordance with those obtained by more tedious ex situ AFM measurements. This confirmed the utility of the streaming potential method for direct kinetic studies of nanoparticle deposition/release processes.Graphical Abstract

Temperature effect on the porosity of hydroxyapatite scaffolds and its use in tissue engineering

“…At the opposing, the effect of heat temperature on HAp and sHA at ~150 °C produced less percentage of porosity and higher zeta potential compared to ~850 and ~1000 °C treatments. As a result, sHA scaffolds treated at ~1000 °C can have potential properties for cell adhesion and proliferation [26][27][28]. According to a study, the Z potential value for hydroxyapatite at this pH should be in the range of 15 mV as seen in the sintered sample at ~850 °C, however given the favorable results of the sample at ~1000 °C [16].…”

Modyfikacja Substratów Stałych Przez Kontrolowaną Adsorpcję Makrojonów

“…It is convenient to express q in terms the average number of elementary charges per molecule considering that it is equal to 1.602×10 -19 C. Such results were extensively discussed in Refs. [41,[57][58][59]. It was calculated that for the standard conditions of 10 -2 M NaCl, pH 5.6, T = 298 K, the number of positive charges per molecule was equal to 63, 46, and 44 for PAH, PDDA and PLL, respectively.…”

Use of Pulsed Streaming Potential with a Prepared Cationic Polyelectrolyte Layer to Detect Deposition Kinetics of Graphene Oxide and Consequences of Particle Size Differences

“…Streaming potential (SP) measurement is a traditional electrokinetic technique for characterizing surfaces. Its application has been extended to in situ determination of the deposition kinetics of proteins, − polyelectrolytes, − and certain colloids onto various surfaces and the stability of the formed layers. , Deposition of nanoparticles (NPs) and their monolayers on polyelectrolyte layers were also described by the Adamczyk group. − The effort to use SP measurement as an analytical tool was made several decades ago. Mattiasson et al proved that SP measurement could be a tool to quantify glycoproteins over an affinity column and to monitor hybridoma cell cultivations .…”