Characterizing the Surface Functionality of Modified Dendrimers as Molecular Nanomaterials

The DelsaNano series is a new generation of instruments that use photon correlation spectroscopy (PCS), which determines particle size by measuring the rate of fluctuations in laser light intensity scattered by particles as they diffuse through a fluid, for size analysis measurements and/or electrophoretic light scattering (ELS), which determines electrophoretic movement of charged particles under an applied electric field from the Doppler shift of scattered light, for zeta potential determination.

This series has a broad range of capabilities, including conventional static and automatic titration measurements for both size and zeta potential distributions of suspended particles in a wide range of size and concentration. The DelsaNano also can measure zeta potential of a solid surface or film.

Functionality of Dendrimers as Molecular Nanomaterials

Dendrimers are representative organic and polymeric nanomaterials used to construct novel devices by accumulative molecular nanomaterials. Dendrimer is a branched polymer whose structure can be precisely controlled. A dendrimer molecule consists of a core and a surface. It is believed that the core determines the size, shape, orientation, and diversity, and that the surface, composed of reactive and nonreactive terminal groups, expresses their functionality.

Modifying Terminal Groups of Dendrimer Molecules

Modification of these terminal groups is being applied to both bioscience and materials science fields. In designing dendrimer molecules, the particle diameter is evaluated as a fundamental physical property. Zeta potential is also significant in determining the surface functionality with terminal group modification.

Mesurement of Zeta Potential and Particle Diameter of PAMAM Dendrimer

In this study, the DelsaNano C, a submicron particle size analyzer, was used to measure the zeta potential and particle diameter of the 1,4-diaminobutane core PAMAM (aliphatic amidoamine-type) dendrimer (hexylamide surface) from Aldrich. The sample has a molecular weight of 83,200 Dalton with 256 terminal groups. The sample concentration was 5 wt% in methanol. The particle size distribution is shown in Figure 1 and the zeta potential distribution is shown in Figure 2. It was determined that the average particle diameter was 8.5 nm and the zeta potential was +7.2 mV because of the positive terminal amino group.

Dendrimer particle size distribution.

Figure 1. Dendrimer particle size distribution.

Dendrimer zeta potential distribution.

Figure 2. Dendrimer zeta potential distribution.

This information has been sourced, reviewed and adapted from materials provided by Beckman Coulter, Inc. - Particle Characterization.

For more information on this source, please visit Beckman Coulter, Inc. - Particle Size Characterization.

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