Flocs or aggregates are formed when phospholipids are mixed with chitosan (preparation of chitosan coated nanoparticles). Is anyone familiar with the chemistry underlying their interactions and formation of aggregates. I do understand that chitosan interacts with phospholipids via electrostatic attraction along with hydrophobic interactions, but i am not able to fathom how these could result in the formation of aggregates.
http://pubs.acs.org/doi/abs/10.1021/jf903270y
See figure A in the file. Imagine that sinuous line is a cationic polymer, chitosan. A drop of this phospholipid cations. These electrostatic interactions. Thermodynamics of the interaction of the authors studied in detail the method of titration calorimetry.
Best regards.
If chitosan-coated NP interacts with and phospolipids by means of attractive electrostatic and hydrophobic forces, this results in the formation of aggregates and flocs, as the solvent is not able anymore to stabilise the dispersion.
Colloidal systems are characterized by a combination of attractive and repulsive interactions, when one of these prevails aggregation is expected. You should look at DLVO theory to a better understanding.
Sometimes, the situation can be even reverse.
Here they are two examples, from different systemm but with almost the same problem
http://pubs.acs.org/doi/abs/10.1021/acs.jpcc.5b08669
http://pubs.acs.org/doi/abs/10.1021/jp501792j
Hope this can help!
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