Complex coacervation in charge complementary biopolymers: Electrostatic versus surface patch binding

• Published in: Advances in colloid and interface science 2017-12, Vol.250, p.40-53
• Main Authors: Pathak, Jyotsana, Priyadarshini, Eepsita, Rawat, Kamla, Bohidar, H.B.
• Format: Article
• Language: English
• Subjects: Biomolecules; Chain flexibility; Complex coacervation; Electrostatic interactions; Surface patch binding
• ISSN: 0001-8686; 1873-3727
• DOI: 10.1016/j.cis.2017.10.006

In this review, a number of systems are described to demonstrate the effect of polyelectrolyte chain stiffness (persistence length) on the coacervation phenomena, after we briefly review the field. We consider two specific types of complexation/coacervation: in the first type, DNA is used as a fixed substrate binding to flexible polyions such as gelatin A, bovine serum albumin and chitosan (large persistence length polyelectrolyte binding to low persistence length biopolymer), and in the second case, different substrates such as gelatin A, bovine serum albumin, and chitosan were made to bind to a polyion gelatin B (low persistence length substrate binding to comparable persistence length polyion). Polyelectrolyte chain flexibility was found to have remarkable effect on the polyelectrolyte-protein complex coacervation. The competitive interplay of electrostatic versus surface patch binding (SPB) leading to associative interaction followed by complex coacervation between these biopolymers is elucidated. We modelled the SPB interaction in terms of linear combination of attractive and repulsive Coulombic forces with respect to the solution ionic strength. The aforesaid interactions were established via a universal phase diagram, considering the persistence length of polyion as the sole independent variable. [Display omitted] •Polyelectrolyte stiffness and charge sequences affected coacervation.•Surface patch binding induced mesophase separation causing complex coacervation between these biopolymers was discussed.•Linear combination of attractive and repulsive forces was used to model the interaction potential.•Repulsion and attraction forces were used with persistence length to construct a universal phase diagram.