Intact deposition of cationic vesicles on anionic cellulose fibers: Role of vesicle size, polydispersity, and substrate roughness studied via streaming potential measurements

Hypothesis: Understanding the mechanism of intact vesicle deposition on solid surfaces is important for effective utilization of vesicles as active ingredient carriers in applications such as drug delivery and fabric softening. In this study, the deposition of large (d(avg) = 12 mu m) and small (d(avg) = 0.27 mu m) cationic vesicles of ditallowethylester dimethylammonium chloride (DEEDMAC) on smooth and rough anionic cellulose fibers is investigated. Experiments: The deposition process is studied quantitatively using streaming potential measurements and spectrophotometric determination of DEEDMAC concentrations. Natural and regenerated cellulose fibers, namely cotton and viscose, having rough and smooth surfaces, respectively, are used as adsorbents. Equilibrium deposition data and profiles of substrate streaming potential variation with deposition are used to gain insights into the fate of vesicles upon deposition and the deposition mechanism. Findings: Intact deposition of DEEDMAC vesicles is ascertained based on streaming potential variation with deposition in the form of characteristic saturating profiles which symbolize particle-like deposition. The same is also confirmed by confocal fluorescence microscopy. Substrate roughness is found to considerably influence the deposition mechanism which, in a novel application of electrokinetic methods, is elucidated via streaming potential measurements. (C) 2016. Elsevier Inc. All rights reserved.