Fabrication of surfactant-polyelectrolyte complex using valvejet 3D printing-aided colloidal self assembly

Complexes consisting oppositely charged surfactants and polyelectrolytes (SPEC) have potential as delivery vehicles for drugs, nutrients and flavours. However, conventional methods for their fabrication often introduce microstructural irregularities owing to poor diffusion of components. Thus, controlled-release capabilities of SPEC cannot be fully realised. Valvejet 3D printing enables spatially and quantitatively controlled layer-by-layer deposition of fluid droplets. Using this technique, alternating layers of chitosan and sodium dodecyl sulphate solutions were 3D printed over one another. Printed specimens were characterised along with control specimens (prepared by film casting) using confocal microscopy, cryo-SEM and elemental analysis. 3D printed samples were found to contain a previously unreported network of interconnected SPEC microcapsules forming a mechanically strong specimen. Micro-CT images confirmed that microcapsules with similar diameter spanned the entire specimen. Control sample was found to have no such microstructure. Elemental analysis revealed that printed sample had excess polyelectrolyte whereas control sample had excess surfactant.