Chitosan-tripolyphosphate bead: the interactions that govern its formation

Chitosan-tripolyphosphate beads are a highly stable and biocompatible polymer-network with versatile applications. In this study, we relate the main synthesis parameters of these particles using a design of experiments and a multivariate calibration to understand how some structural characteristics (mass, diameter and water retention capacity) of these spherical hydrogels are achieved from the point of view of the ionotropic association between chitosan chains and tripolyphosphate molecules. The results conduct to a better conceptualization of the crosslinking process, establish the ranges where particles with different structural characteristic can be obtained and a better understanding of how the physicochemical behavior of the chitosan and the tripolyphosphate affect the structural parameters of the chitosan-tripolyphosphate beads. As a novelty, we propose a refined 3D junction zone for the interaction between the raw molecules that allows to conclude that one TPP molecule can associate with up to three amino groups as a maximum.