Polyamine Colloids Cross-Linked with Phosphate Ions: Towards Understanding the Solution Phase Behavior |
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Authors: | Dr. Santiago E. Herrera Dr. Maximiliano L. Agazzi Dr. M. Lorena Cortez Dr. Waldemar A. Marmisollé Dr. Mario Tagliazucchi Dr. Omar Azzaroni |
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Affiliation: | 1. Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), CONICET, La Plata, 1900 Argentina;2. INQUIMAE-CONICET, Ciudad Universitaria, Pabellón 2, Ciudad Autónoma de Buenos Aires, Buenos Aires, C1428EHA Argentina |
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Abstract: | Ionically crosslinked poly(allylamine)/phosphate (PAH/Pi) colloids consist of self-assembled nanostructures stabilized by supramolecular interactions. Under physiological conditions, these interactions should be present at high ionic strength and only in a narrow pH window to be effective as drug delivery agents. In this work we study the effect of the pH and ionic strength in the chemical behaviour of inorganic phosphate (Pi), poly(allylamine hydrochloride) (PAH) and their mixture in aqueous solution (PAH−Pi). By combination of experimental measurements and a theoretical model, we demonstrate that the driving force that leads to the formation of colloids is the electrostatic pairing between the positively charged amino groups in PAH and negatively charged HPO42− ions. Increasing the ionic strength of the system by addition of KCl weakens the PAH−Pi interactions and narrows the pH stability window from 4 to 1.8 pH units. In addition, a fully reversible system was obtained in which the colloids assemble and disassemble by changing the pH between 6.8 and 7.1 at high ionic strength, making them suitable for use as pH-responsive nanocarriers. |
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Keywords: | colloids crosslinking PAH phosphates supramolecular chemistry |
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