Karthikeyan Pasupathy, Nicholas W. Suek, John L. Lyons, Justin Ching, Aaron Jones, Qi Lu, Monica H. Lamm, Pu Chun Ke
Laboratory of Single-
Molecule Biophysics and Polymer Physics, Clemson University,
Clemson, SC 29634, USA; Tel: 864-656-0558; Fax: 864-656-0805; E-mail:
email@example.com; the Department of Chemical and Biological Engineering,
Iowa State University, Ames, IA 50011, USA.
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We report our single-molecule fluorescence microscopy and molecular dynamics simulation studies on the interaction
of poly(amidoamine) dendrimer and squalane hydrocarbon in aqueous solution. Our spectrophotometry measurements
indicate that this interaction increases with the pH of the solvent. Our simulations show that squalane resides
primarily on the perimeter of the dendrimer at low to neutral pH, but becomes encapsulated by the dendrimer at high pH.
Using single-molecule fluorescence microscopy, we have identified that the binding between PAMAM and squalane is
reversible. At a pH value of 8, the approaching, binding, and characteristic times of a single fluorescently-labeled dendrimer
to squalane are 0.5 s, 7.5 s, and 0.5 s, respectively. Both our spectrophotometry measurements and simulations
show that the interaction between PAMAM and squalane is stronger for lower generation dendrimers. This study facilitates
our understanding of using dendritic and hyperbranched polymers for gas hydrate prevention in the petroleum industry.