Quantifying Nanoparticle Aging Using Wetted Surface Area Measurements

Table of Content

Properties and Applications of AuNP and AgNP
Production of AuNP and AgNP
Non-destructive Measurement of Samples
About XiGo Nanotools


Gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) have unique and attractive physical and chemical properties, and as such have been the subject of intensive research.

These properties include photothermal response, high electrical and thermal conductivity, and tunable optical properties. This article describes the measurement of the effects of accelerated aging of AuNPs and AgNPs.

Properties and Applications of AuNP and AgNP

The applications and properties of AgNPs and AuNPs depend on their shape and size; even round particles may not be entirely smooth. Their large surface area-to-volume ratio allows the particle surface to be coated with many different types of functional molecule, including anti-fouling polymers, therapeutics, and targeting agents.

Both AgNPs and AuNPs are utilized in a wide range of applications, such as imaging, diagnostics, sensory probes, organic photovoltaic, drug delivery, therapeutic agents, coatings, conductive inks, electronic resistors, and capacitors. AgNPs are more commonly used due to their antimicrobial properties.

Production of AuNP and AgNP

A large number of AgNPs and AuNPs are produced in situ by precipitation and nucleation processes in both aqueous and non-aqueous media at different concentrations. As a result, meticulous characterization is important to achieve the best performance and cost-effective benefits from such systems.

The XiGo Acorn Area is a compact, patented bench-top NMR instrument that enables users to directly determine the entire wetted surface area of AgNPs and AuNPs as they are prepared, without dilution. The device can also be utilized to examine the adsorption of polymers and surfactants onto their surface.

Non-Destructive Measurement of Samples

In order to gain a better insight into the effects of storage conditions on shelf-life, formulations are kept under stable test conditions and thoroughly studied at regular intervals. It is important to test regulated products according to ICH guidelines.

As the particle size increases, the color of both AgNPs and AuNPs changes correspondingly. This property can be utilized to qualitatively assess the onset of aggregation. When aggregation occurs, the total wetted surface area will clearly decrease. This change can be determined quantitatively from NMR relaxation, using the Acorn Area device.

Moreover, since the measurement is non-destructive and non-invasive, samples can be maintained under any conditions and then re-examined at a later period. Figures 1 illustrate data for samples of AgNPs and AuNPs stored at 40°C and quantified over four weeks and four months, respectively.

Figure 1. Data for samples of AgNP and AuNP stored at 40°C and measured over four weeks and four months, respectively.


XiGo’s Acorn Area device helps in direct determination of the total wetted surface area of silver and gold nanoparticles. This NMR instrument can even be utilized to examine the adsorption of polymers and surfactants onto their surface.

About XiGo Nanotools

XiGo Nanotools was founded by Sean Race and Dr. David Fairhurst in 2005 with the mission to provide new innovate “tools” for the emerging nanomaterials industry. The Acorn Area is designed to measure the wetted surface area of concentrated dispersions with little or no sample preparation, providing a viable complementary technique to BET surface area, analyzing nanoparticles as they are made or used, dispersed in liquids.

Our goal is to provide scientists, researchers, and corporations with tools that are easy to use and serve as wide and diverse a customer base as possible. We have incorporated the latest technology available into an integrated, high quality package that provides precise measurements in a very small footprint.

This information has been sourced, reviewed and adapted from materials provided by XiGo Nanotools.

For more information on this source, please visit XiGo Nanotools.

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