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Published on: August 22, 2015
Nanoparticle size determination by (1)H NMR spectroscopy.
M Victoria Gomez1, Javier Guerra, V Sue Myers
1Instituto Regional de Investigación Científica Aplicada (IRICA) and Departamento de Química Orgánica, Facultad de Química, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain.
Journal of the American Chemical Society
|September 30, 2009
Summary
High-resolution NMR spectroscopy can determine the size of palladium dendrimer-encapsulated nanoparticles (DENs). This method correlates proton NMR signal changes with nanoparticle size, aiding in DENs characterization.
Area of Science:
- Materials Science
- Nanotechnology
- Analytical Chemistry
Background:
- Dendrimer-encapsulated nanoparticles (DENs) offer unique properties for various applications.
- Accurate characterization of DEN size is crucial for understanding their behavior.
- Poly(amidoamine) (PAMAM) dendrimers are widely used hosts for nanoparticle synthesis.
Purpose of the Study:
- To develop and validate a method for determining the size of palladium (Pd) DENs using (1)H NMR spectroscopy.
- To establish a correlation between NMR signal intensity and the number of Pd atoms in DENs.
- To confirm the absence of nanoparticle aggregation within the dendrimer structure.
Main Methods:
- High-resolution solution (1)H NMR spectroscopy was employed to analyze Pd DENs.
- Pd DENs were synthesized with varying nanoparticle sizes (55, 147, 200, 250 atoms) encapsulated in sixth-generation hydroxyl-terminated PAMAM dendrimers (G6-OH).
- NMR pulse-field gradient spin-echo experiments were conducted to assess hydrodynamic radii and detect aggregation.
Main Results:
- A significant decrease in the integral value of innermost G6-OH protons was observed with increasing Pd nanoparticle size.
- A mathematical correlation was established between the decrease in NMR signal integral and the theoretical number of Pd atoms.
- Identical hydrodynamic radii for G6-OH with and without DENs confirmed the absence of dendrimer/nanoparticle aggregates.
Conclusions:
- Solution (1)H NMR spectroscopy is a viable technique for elucidating the size of Pd DENs.
- The established mathematical correlation provides a quantitative method for size determination.
- The study confirms the successful encapsulation of discrete Pd nanoparticles within G6-OH dendrimers without aggregation.
