Topographical and photophysical properties of poly(amidoamine) dendrimers with ionic surfactants

The atomic force microscopy (AFM) and transmission electron microscopy (TEM) have been performed on the poly(amidoamine) dendrimers of second generation (2G) and its fluoroderivative (2D) at room temperature. Both studies have demonstrated that 2G and 2D exist in large aggregates on solid surface. The presence of ionic surfactants facilitates their solubilization in micellar phase resulting in the aggregates of much smaller dimensions. The aqueous bulk properties of 2G and 2D both in the absence as well as in the presence of ionic surfactants (i.e. dodecyltrimethylammonium bromide (DTAB), dimethylene bis (dodecyldimethylammonium bromide) (12-2-12), and sodium dodecyl sulfate (SDS)) have been carried out with the help of pyrene fluorescence and turbidity (τ) measurements. From the variation of I1/I3 pyrene intensity and the τ of these aqueous solutions, it has been found that both DTAB and 12-2-12 interact with the surface groups of 2G and 2D favorably in basic medium, while SDS has been found to interact with that in acidic medium. Apart from this, interactions of cationic surfactants have been found to be stronger with 2D in comparison to 2G, while reverse has been observed in the case of SDS.