Effect of triblock copolymers on the lipase catalytic behavior at the interface of conventional O/W emulsions

Abstract

The ‘interfacial quality’ is the key influencing factor for lipase activities at interfaces, and thus, interfacial engineering has become an effective strategy to modulate lipase catalysis. In the current research, the triblock copolymers poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) (PEO-PPO-PEO) were adopted to form conventional oil-in-water (O/W) emulsion systems. The results showed the different effects of PEO-PPO-PEO molecules on the spatial barriers, emulsion particle size, and ultimately interfacial adsorption properties of lipases. Since the molecular weight of Candida antarctica lipase B (CALB) is approximately half that of Candida rugosa lipase (CRL), it can more easily pass through the triblock copolymer adsorption layer, resulting in a higher adsorption ratio. The results confirmed that the catalytic efficiency of CALB at the emulsion interfaces was much lower than that of CRL due to its lack of a typical ‘lid’ structure. Both the effective amount of lipase molecules at the interfaces (controlled by the interfacial adsorption ratio) and the effective catalytic interface area (influenced by the specific surface area controlled by the average particle size of the O/W emulsion) impacted the catalytic activities of CRL. Na+ ions were found to have a certain inhibitory effect on the catalytic activity of CRL.