Encapsulation of Synthetically Valuable Biocatalysts into Polyelectrolyte Multilayer Systems

Abstract

Layer-by-Layer (LbL) technology recently turned out to be a versatile tool for the encapsulation of bioactive entities. In this study, the factual potential of this technology to encapsulate synthetically valuable biocatalysts, that is enzymes and whole cells expressing a specific catalytic activity, was investigated. The biocatalysts were embedded into a polyelectrolyte multilayer system involving poly(allylamine) hydrochloride (PAH) and poly(styrene sulfonate) sodium salt (PSS). The enzymes were adsorbed to CaCO3 or DEAE-cellulose previous to encapsulation. A slight increase (32%) of the catalytic performance was observed for lipase B from Candida antarctica when four layers of polyelectrolytes were applied. On the whole, however, the residual activity of the investigated enzymes after encapsulation was rather low. Similar results were obtained with whole-cell biocatalysts. It was found that the activity decrease can be attributed to mass transfer restrictions as well as direct interactions between polyelectrolytes and catalytically active molecules. Both effects need to be understood in more detail before LbL technology can be advanced to technically efficient biocatalysis.

Location of molecules in layer-by-layer assembled microcapsules influences activity, cell delivery and susceptibility to enzyme degradation

“…Previous studies with LbL assembled films have shown that enzyme activity typically decreases as they are placed in deeper layers due to reduced access of substrate through the covering layers of polyelectrolytes [9,10]. When enzymes such as lipase B and glucose oxidase have been incorporated into synthetic microcapsules the same observation has been made, with lower activity of enzyme in the core attributed to reduced mass transfer of substrate [11,12]. We have recently utilised the bioluminescent enzyme firefly luciferase to examine the influence that different locations in biodegradable microcapsules has on activity.…”

“…This structural organisation explains why in intact microcapsules D-luciferin substrate and co-factors (ATP and divalent cations) are slow to react with core luciferase. Studies performed by Wiemann et al (2009) with encapsulated enzymes noted that the polyelectrolyte capsule structure impacts on the mass transfer of substrates and/or products, and calculated a decrease of enzyme activity of about 10% per polyelectrolyte layer added [11].…”

Enzyme Immobilization by Microencapsulation: Methods, Materials, and Technological Applications

“…In the kinetic resolution of 1,2-O-isopropylidenglycerolesters, enantioselectivity dropped from 95% to 34% upon encapsulation. In contrast, the use of the same encapsulation protocol resulted in 1.32-fold increase in the activity of CalB (127).…”

“…These interactions can result in decreased intrinsic enzyme activity (e.g. creation of steric hindrance around the active site) or true inactivation (126,127). Benzaldehyde lyase from Pseudomonas fluorescens and alcohol dehydrogenase from Lactobacillus brevis showed almost no activity after encapsulation into PAH/PSS microcapsules.…”

Enzyme-Encapsulated Layer-by-Layer Assemblies: Current Status and Challenges Toward Ultimate Nanodevices

“…AnsorgeSchumacher and coworkers very recently pointed out the importance of the combination of capsules' polyelectrolyte, reactants, and enzyme [232]. The biocatalysts (lipase B) were adsorbed to CaCO 3 or DEAE-cellulose colloidal cores on which LbL multilayers of PAH and PSS had been coated.…”