Tapping Mode Atomic Force Microscopy Investigation of Poly(amidoamine) Core-Shell Tecto(dendrimers) Using Carbon Nanoprobes

Langmuir, 18 (8), 3127 -3133, 2002. 10.1021/la025538s S0743-7463(02)05538-5
Web Release Date: March 9, 2002

Tapping Mode Atomic Force Microscopy Investigation of Poly(amidoamine) Core-Shell Tecto(dendrimers) Using Carbon Nanoprobes

Theodore A. Betley, Jessica A. Hessler, Almut Mecke, Mark M. Banaszak Holl,* Bradford G. Orr,* Srinivas Uppuluri, Donald A. Tomalia, and James R. Baker, Jr.

Departments of Chemistry and Physics and the Center for Biologic Nanotechnology, University of Michigan, Ann Arbor, Michigan 48109

Received January 15, 2002

Abstract:

Carbon nanoprobes were utilized in tapping mode atomic force microscopy investigations to highlight the topographic differences between poly(amidoamine) (PAMAM) dendrimers, two-dimensional arrays of PAMAM dendrimers, and PAMAM core-shell tecto(dendrimers). The PAMAM core-shell tecto(dendrimers) used for this study consist of a shell of generation five (G5) dendrimers covalently linked to a G7 core. The volumes measured for the PAMAM core-shell tecto(dendrimers) suggest a 75-100% saturation of shell G5 dendrimers about the G7 core. This compares favorably with theoretical predictions that 12 G5 dendrimers should pack to form a shell about a G7 core. The effect of different imaging substrates was also explored. Tecto(dendrimers) imaged on hydrophobic surfaces experience a 6-fold increase in maximum peak height and a 3-fold decrease in diameter as compared to those imaged on mica. Measured volume is invariant.

Download the full text: PDF | HTML