Purification and Characterization of Dendrimers

Various methods of dendrimers characterization have been elaborated such as NMR, electron paramagnetic resonance, mass spectrometry, UV–VIS spectrometry, time-resolved and nonlinear optical spectroscopy, laser light scattering, optical rotation, circular dichroism, synchrotron radiation-based circular dichroism, IR, Raman, fluorescence, X-ray diffraction, small-angle X-ray scattering, small-angle neutron scattering, atomic force microscopy, scanning tunneling microscopy, optical tweezers, transmission electron microscopy, isothermal titration calorimetry, different chromatographic and electromigration methods (electrophoresis, capillary electrophoresis), dielectric spectroscopy, differential scanning calorimetry. Hence, this chapter is focused only on some ways, which are important for dendrimer characterization. Their con and pros are clearly discussed. Dendrimers can be characterized and purified by separation methods, as well as, they can be employed as stationary phase and/or selection factors improving the efficacy of separation techniques. The two main classes of separation techniques are chromatographic and electromigration methods. Even combination of two complementary techniques is not sufficient for removal of all by-products differing by only a single modification or deletion (the negligible difference such as missing one amino acid in molecules with mass above 7 kDa). A battery of complementary methods must be used to ensure at least some degree of reliability and even then the X + 1 method can show some impurities. By other words, the purity depends on the purification processes and analytical methods used.