Polyamidoamines (PAAs) represent a family of degradable polymers carrying tert-amine groups in the polymer backbone, which behave as polyelectrolytes in aqueous solutions Many relevant properties of PAAs, including the ability to interact with components of the biological environments, such as nucleic acids, proteins, and living cells, are strongly dependent on their acid-base properties, hence on their ionization state in different biological districts In this article, the protonation constants of a series of PAAs have, been precisely determined by electrochemical techniques in order to build tip a homogeneous library containing both the protonation constants and the average distribution of the charged species, hence the net average charge as a function of pH Moreover, correlations between chemical and cytotoxicity, have been attempted (C) 2009 Wiley Periodicals, Inc J Polym Sci Part A Polym Chem 47. 6977-6991, 2009