title: Assembly-Controlled Permeability of Layer-by-Layer Polymeric Microcapsules Using a Tapered Fluidized Bed.
abstract: Nano- and microcapsules engineered through layer-by-layer (LbL) assembly are finding an increasingly large number of applications as catalysts, electrochemical biosensors, bioreactors, artificial cells and drug delivery vehicles. While centrifugation-based LbL assembly is the most common method for coating template particles and preparing capsules, it is a batch process and requires frequent intervention that renders the system challenging to automate and scale up. Here, we report the use of a tapered fluidized bed (TFB) for the preparation of multilayered polymer capsules. This is a significant improvement over our recent approach of fluidizing particles in cylindrical fluidized beds (CFB) for LbL assembly. We demonstrate that TFB is compatible with particles <3 μm in diameter (an order-of-magnitude improvement compared with CFB), which can be fluidized with minimal entrainment. Additionally, layering materials were expanded to include both electrostatic and hydrogen-bonding polymer pairs (e.g., poly(allylamine hydrochloride) (PAH) and poly(styrenesulfonate) (PSS), and thiol-modified poly(methacrylic acid) (PMASH) and poly(N-vinylpyrrolidone) (PVPON), respectively). Finally, differences between capsules prepared via centrifugation-based and TFB LbL assembly were investigated. The obtained TFB microcapsules demonstrate increased film thickness and roughness compared with those prepared using centrifugation-based LbL assembly. Furthermore, PMASH microcapsules exhibit lower swelling and permeability when prepared via TFB LbL assembly compared with centrifugation-based LbL assembly due to enhanced multilayer deposition, entanglement, and cross-linking. Therefore, polymeric capsules fabricated via TFB LbL assembly may be useful for encapsulation and retention of relatively low molecular weight (∼20 kDa) hydrophilic biomacromolecules to passively or responsively release the payload for drug delivery applications.
authors.affiliation: Australian Research Council (ARC) Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Department of Chemical and Biomolecular Engineering, The University of Melbourne , Parkville, Victoria 3010, Australia.
authors.forename: Ka Fung
authors.initials: KF
authors.lastname: Noi
authors.affiliation: Australian Research Council (ARC) Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Department of Chemical and Biomolecular Engineering, The University of Melbourne , Parkville, Victoria 3010, Australia.
authors.forename: Ali
authors.initials: A
authors.lastname: Roozmand
authors.affiliation: Australian Research Council (ARC) Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Department of Chemical and Biomolecular Engineering, The University of Melbourne , Parkville, Victoria 3010, Australia.
authors.forename: Mattias
authors.initials: M
authors.lastname: Björnmalm
authors.affiliation: Australian Research Council (ARC) Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Department of Chemical and Biomolecular Engineering, The University of Melbourne , Parkville, Victoria 3010, Australia.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Richardson
authors.affiliation: Department of Chemical and Biomolecular Engineering, The University of Melbourne , Parkville, Victoria 3010, Australia.
authors.forename: George V
authors.initials: GV
authors.lastname: Franks
authors.affiliation: Australian Research Council (ARC) Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Department of Chemical and Biomolecular Engineering, The University of Melbourne , Parkville, Victoria 3010, Australia.
authors.forename: Frank
authors.initials: F
authors.lastname: Caruso
mesh_terms: D015374:Biosensing Techniques; D002214:Capsules / Q000138:chemical synthesis / Q000737:chemistry*; D016503:Drug Delivery Systems; D006860:Hydrogen Bonding; D010539:Permeability; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D011760:Pyrrolidinones / Q000737:chemistry
chemical_list: D002214:Capsules; D011108:Polymers; D011760:Pyrrolidinones; C042670:N-vinyl-2-pyrrolidinone
keywords: layer-by-layer; microcapsule; nanofilm properties; permeability; swelling