Assembly of biomacromolecule loaded polyelectrolyte multilayer capsules by using water soluble sacrificial templates

Abstract

In the quest for greater control over biomacromolecular loading and higher encapsulation efficiencies for biomacromolecule loaded microcapsules we devised a novel approach employing water soluble sacrificial templates. In traditional layer by layer (LbL) methods, aqueous solutions of polyelectrolyte salts in combination with water insoluble sacrificial template materials are used to prepare polyelectrolyte microcapsules that can be loaded with biomacromolecules. Here, we replaced the aqueous phase with pure aliphatic alcohols (Reversed-Phase) to greatly enhance the retention of biomacromolecular cargo close to 100% during microcapsule preparation in this Reverse-Phase Layer by Layer (RP-LbL) process. Formation of stable multilayered polyelectrolyte membranes onto water soluble template materials by sequential deposition of polystyrenesulfonic acid (PSS) and polyallylamine (PA) from pure 1-butanol is reported for the first time. The challenge to exert control over the biomacromolecule concentration within the template material and the resulting microcapsules was addressed by sacrificial template materials. Sacrificial template materials are water soluble and comprise of biomacromolecules embedded into a matrix of small molecular weight molecules such as glucose. Control over the concentration of biomacromolecules in the template material and microcapsules is conveniently exerted by adjusting weight ratios of bimacromolecules to sacrificial template material. This approach is envisioned to be applied alternatively to traditional polyelectrolyte microcapsule preparation techniques in cases where minute losses of expensive biomacromolecules are unfavorable or when accurate control over biomacromolecule concentration is important.