Characterizing the Zeta Potential & Isoelectric Point of Nanomaterials

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00:00:00 Welcome
00:00:11 Introduction
00:00:44 Zeta Potential & Isoelectric Point Characterization
00:00:55 Objectives
00:02:00 Pharmaceutical Coatings
00:03:00 Targeted Drug Delivery Systems
00:04:24 Cosmetics / Personal Care
00:05:25 Paints & Industrial Coatings
00:07:04 Part Two: Measurement, Double Layer, Resulting Zeta Potential
00:07:24 What is Zeta Potential?
00:08:53 DLVO Theory, 1940’s
00:13:21 Electrophoretic Light Scattering
00:14:20 Optical Configuration
00:16:36 Electrophoretic Light Scattering(Zeta Potential)
00:18:10 Measurement Cells (for use under 70C)
00:20:22 Diffusion barrier technique
00:23:54 Electro-Osmosis and ELS
00:26:33 Eliminating Electroosmosis:Aqueous/Non-Aq Dip Cell
00:27:31 Mobility vs. Cell Position 0.5Hz & 50Hz
00:28:53 Mobility Results vs. Frequency
00:30:01 Mixed Mode Measurement (M3)
00:31:20 Phase Plot From General Purpose
00:36:06 Maintaining Dispersion Stability
00:36:11 ELECTROSTATICS:Origins of Surface Charge in Aqueous Media
00:36:25 Untitled
00:38:31 Polymer Adsorption
00:41:09 Predicting Dispersion Stability
00:41:31 Zeta Potential and pH
00:42:35 Effect of pH on Particle Charge
00:42:40 Zeta Potential and Conductivity
00:42:57 Non Specific Ion Adsorption
00:43:42 Specific Ion Adsorption
00:43:47 Part Three: Isoelectric Points
00:43:47 Titration Example
00:45:05 Isoelectric Points
00:46:59 Origin of Charge in Clays
00:48:10 Surface Charge - Neutral Conditions (pH7)
00:49:12 Example Isoelectric Points of Oxides
00:50:06 Part Four: Formulation- Sunscreens/Sun Lotions
00:50:06 Photochemistry and Photobiology of the Skin
00:50:54 Sunscreen Agents: Two Kinds
00:51:57 Physical (Particulate) Sunscreen Materials
00:52:40 Microfine Metal Oxide UVR Attenuation Spectra
00:53:04 Uncoated Titanium Dioxide & Zinc Oxide
00:54:13 Surface Treated Titanium Dioxide & Zinc Oxide
00:55:05 Untitled
00:55:48 Particle Size Growth ZnO & TiO2 (pH 7.0)
00:57:24 Conclusion
00:58:56 Thank you for your attentionAny questions?
01:06:42 Contact Information

Zeta potential is a function of both the particle surface and the dispersant medium. It is an important predictor of electric or charge stabilization and can also be used to identify the adsorption of non-ionic or steric layers. In short, zeta potential provides key information about the interfacial behavior of multicomponent formulated products.

Particles acquire a surface charge when exposed to a polar medium like water. There are many origins of this surface charge depending upon the nature of the particle and it’s surrounding medium. Typically, materials in water are negatively charged but there are some materials that are positively charged. An isoelectric point (IEP), is the pH at which a molecule or material carries the average nett charge of zero. The IEP can affect the solubility of a molecule at a given pH. Materials typically have minimum stability or minimal solubility in water or salt solutions at the IEP and often coagulate or precipitate out of solution at this pH. The IEP also indicates the acidity and alkalinity of the material. Again, the zeta potential is affected by both the particulate, or dispersed phase, as well as the dispersion medium. Zeta potential is important in evaluating product consistency, product quality and final product performance.

In this presentation, we will discuss zeta potential measurements, zeta potential theory, charging mechanisms that affect surface interfacial behavior and isoelectric point determination.


Dr Ana Morfesis is Applications Specialtist for our Nanometrics product group. She joined Malvern in 1999 and works with us in conjunction with the Carnegie Mellon University Lab. Ana has a PhD in Physical Chemistry from the University of Massachusetts. Her area of research has been colloid and surface chemistry since the early 1980's.

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Why attend?
Learn about zeta potential and how it can help you to formulate products.

Who should attend?
Formulation scientists working in pharmaceuticals, drug delivery, surfactants, personal care, industrial coatings, paper products, ceramics and academic researchers studying interfacial and surface behavior of two phase suspensions and complex fluids