Nanoparticles in sensing applications: on what timescale do analyte species adsorb on the particle surface?

Abstract

The recent decade saw much interest in sensors based on nanoparticles. Such sensors typically employ sensing mechanisms that utilise the adsorption of analyte species on the nanoparticle surfaces, while adsorption induces changes in the physical properties of the nanoparticles. In this work, we introduce an analytical model for the rate of adsorption of analyte species on the nanoparticle surface. Expressions for the fractional surface coverage and the number of adsorbed molecules as a function of time are derived assuming spherical nanoparticles. Moreover, we provide values for common experimental conditions and show that for small nanoparticles (r < 10 nm) a surface coverages of 30% can be reached in less than 1 s at adsorbent concentrations as low as 50 nM.

In Situ Metalorganic Deposition of Silver Nanoparticles on Gold Substrate and Square Wave Voltammetry: A Highly Efficient Combination for Nanomolar Detection of Nitrate Ions in Sea Water

“…Adsorption times for NO 3 − depends of the size of the nanoparticles, of the diffusion coefficient and of the concentration. The analytical model developed by Compton indicates that for small NPs (<10 nm) a surface coverage with NO 3 − higher than 30% may be reached in less than a second for very low concentrations (<50 nM) [35]. Consequently, when the CV experiment begins it is assumed that NO 3 − species are already adsorbed on the electrode surface.…”

Magnetic bead and gold nanoparticle probes based immunoassay for β-casein detection in bovine milk samples

“…On the other hand, the accelerated analyte species transport to the nanoparticle surface significantly reduce the time that is required to perform a measurement (Katelhon and Compton, 2014). Magnetic beads (MBs) can be easily separated from the reaction mixtures with a magnet and re-dispersed immediately following removal of the magnet (Wei et al, 2012) which allow for a nearly 'in solution' reaction (Kim et al, 2009), leading to shorter reaction times .…”

A one-pot hydrothermal synthesis of graphene/CdS:Mn photocatalyst for photoelectrochemical sensing of glutathione

“…Nevertheless, the spectral and chromatographic methods are complicated due to pre-treatment procedures, while electrochemical detection suffers from the interference of some easily oxidative substances or a relatively high oxidation potential. [7][8][9] Photoelectrochemical (PEC) sensing is a novel and promising analytical technique, it has attracted considerable attention. 10 Owing to the complete separation of excitation source (light) and detection signal (current), PEC sensor has low background noise and high sensitivity in comparison with conventional pristine optical and electrochemical methods.…”