Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Ionic Strength: Effects on Chemical Equilibria

Ionic Strength: Effects on Chemical Equilibria

The addition of an inert ionic compound increases the solubility of a sparingly soluble salt. For example, adding potassium nitrate to a saturated solution of calcium sulfate significantly enhances the solubility of calcium sulfate. Le Châtelier's principle cannot predict this shift in the equilibrium. Instead, this could be explained in terms of changes in the effective concentration of the ions in solution in the presence of added inert salt.
In this solution, the primary cation—the calcium...

Ionic Strength: Overview

Ionic Strength: Overview

The ionic strength of a solution is a quantitative way of expressing the total electrolyte concentration of a solution. This concept was first introduced in 1921 by two American physical chemists, Gilbert N. Lewis and Merle Randall, while describing the activity coefficient of strong electrolytes. During the calculation of ionic strength (I or μ), all the cations and anions are considered. However, the concentration (c) of an ion with a greater charge number (z) has a greater contribution to...

Colloidal precipitates

Colloidal precipitates

The high insolubility of some precipitates can result in an unfavorable relative supersaturation. This can lead to colloidal particles with a large surface-to-mass ratio, where adsorption is promoted. For instance, in the precipitation of silver chloride, silver ions are adsorbed on the surface of the colloidal particles, forming a primary layer. This layer attracts ions of opposite charge (such as nitrate ions), forming a diffuse secondary layer of adsorbed ions. This electric double layer...

Formation of Complex Ions

Formation of Complex Ions

A type of Lewis acid-base chemistry involves the formation of a complex ion (or a coordination complex) comprising a central atom, typically a transition metal cation, surrounded by ions or molecules called ligands. These ligands can be neutral molecules like H2O or NH3, or ions such as CN− or OH−. Often, the ligands act as Lewis bases, donating a pair of electrons to the central atom. These types of Lewis acid-base reactions are examples of a broad subdiscipline called coordination...

Common Ion Effect

Common Ion Effect

Compared with pure water, the solubility of an ionic compound is less in aqueous solutions containing a common ion (one also produced by dissolution of the ionic compound). This is an example of a phenomenon known as the common ion effect, which is a consequence of the law of mass action that may be explained using Le Châtelier’s principle. Consider the dissolution of silver iodide:

Precipitation Titration: Endpoint Detection Methods

Precipitation Titration: Endpoint Detection Methods

In argentometric precipitation titrations, endpoints can be detected visually by the Mohr, Volhard, and Fajans methods. In the Mohr method, adding a soluble chromate indicator gives an initial yellow color to the analyte solution. As the titrant is added, the first excess of silver ions forms a red silver chromate precipitate, marking the endpoint. The solution pH should be maintained at about 8 by adding solid CaCO3.
In the Volhard method, a standard excess of AgNO3 is first added to the...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Outcomes of emergency resuscitative thoracotomies in a trauma unit in Johannesburg, South Africa.

South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde·2026

Same author

Statistical analysis plan for Love Your Brain: a multi-arm randomised controlled trial of a stroke prevention digital platform.

Trials·2026

Same author

Le Fort III fractures: An approach to resuscitation and management.

Annals of medicine and surgery (2012)·2022

Same author

Reference Protocol to Assess Analytical Performance of Higher Order Structural Analysis Measurements: Results from an Interlaboratory Comparison.

Analytical chemistry·2021

Same author

Assessment of methods for determination of glycan composition of erythropoietin.

Pharmeuropa bio & scientific notes·2019

Same author

Author Correction: Inhibition of casein kinase 1δ/εimproves cognitive-affective behavior and reduces amyloid load in the APP-PS1 mouse model of Alzheimer's disease.

Scientific reports·2019

Search research articles

Related Experiment Video

Updated: Jun 28, 2026

Gold Nanoparticle Synthesis

Gold Nanoparticle Synthesis

Published on: July 10, 2021

Solution ionic strength effect on gold nanoparticle solution color transition.

C Burns¹, W U Spendel, S Puckett

¹Miami University Center for Nanotechnology, Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA.

|October 31, 2008

Summary

This summary is machine-generated.

Gold nanoparticles act as sensors, changing color from red to blue based on ionic content. Multivalent cations cause a more sensitive color change, indicating surface adsorption, not aggregation, is key.

More Related Videos

Hydroquinone Based Synthesis of Gold Nanorods

Hydroquinone Based Synthesis of Gold Nanorods

Published on: August 10, 2016

Synthesis and Characterization of Amphiphilic Gold Nanoparticles

Synthesis and Characterization of Amphiphilic Gold Nanoparticles

Published on: July 2, 2019

Related Experiment Videos

Last Updated: Jun 28, 2026

Gold Nanoparticle Synthesis

Gold Nanoparticle Synthesis

Published on: July 10, 2021

Hydroquinone Based Synthesis of Gold Nanorods

Hydroquinone Based Synthesis of Gold Nanorods

Published on: August 10, 2016

Synthesis and Characterization of Amphiphilic Gold Nanoparticles

Synthesis and Characterization of Amphiphilic Gold Nanoparticles

Published on: July 2, 2019

Area of Science:

Nanotechnology
Analytical Chemistry
Materials Science

Background:

Gold nanoparticles (AuNPs) are utilized in various sensing applications.
The optical properties of AuNPs, such as their surface plasmon resonance, are sensitive to their surrounding environment.
Understanding the factors influencing AuNP optical changes is crucial for developing reliable sensors.

Purpose of the Study:

To investigate the effect of ionic content on the optical properties of gold nanoparticles.
To determine the mechanism behind the red to blue color transition in gold nanoparticle sensors.
To compare the sensitivity of gold nanoparticle sensors to monovalent versus multivalent cations.

Main Methods:

Standard gold nanoparticle solutions were prepared.
Titration experiments were conducted using monovalent and multivalent cation salts.
UV-Vis spectroscopy was employed to monitor color changes (red to blue transition).
Analysis of Debye length and surface adsorption mechanisms was performed.

Main Results:

Ionic content significantly impacts the color transition of gold nanoparticles.
Multivalent cation salts demonstrated higher sensitivity to color change compared to monovalent salts.
The predominant mechanism for the observed red to blue color change was identified as specific surface adsorption, not aggregation.
Surface electrodynamic resonance effects, influenced by Debye lengths (3-7nm for divalent, 0.5-1.5nm for monovalent), are important factors.

Conclusions:

Gold nanoparticles can serve as effective sensors indicated by their red to blue color transition.
Ionic content, particularly multivalent cations, is a critical parameter for sensor performance and sample analysis.
Specific surface adsorption and surface electrodynamic resonance are key mechanisms driving the color change in these gold nanoparticle sensors.