Encapsulation and surface charge manipulation of organic and inorganic colloidal substrates by multilayered polyelectrolyte films

• Bovine serum albumin protein nanoparticles were synthesized by coacervation process.
• BSA and SiO2 particles could be encapsulated by multilayered polyelectrolyte films.
• Higher ζ-potential of BSA helps to keep the polyelectrolyte chains unfolded.
• Smooth capsulation layers could be formed over BSA nanoparticles.
• Nature of polyelectrolyte determines the nature of surface charge and ζ-potential.

Employing layer-by-layer (LbL) technique we could encapsulate both organic and inorganic nano- and microparticulate substrates by multilayer polyelectrolyte films of variable thicknesses. It has been observed that the uniformity of the polyelectrolyte multilayer does not depend severely on the chemical nature of particulate substrate; rather it depends on the initial surface charge density or ζ-potential of their bare surface. Higher ζ-potential of organic albumin nanoparticles helps to keep the polyelectrolyte chains unfolded. On the other hand, a lower ζ-potential of inorganic microparticles such as SiO2 induces a folding of dangling polyelectrolyte chains, forming domains of their aggregates or complexes at the particle surface, making the encapsulating multilayer inhomogeneous.

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