Enzymatic Degradation of Polyester-Nanoparticles by Lipases and Adsorption of Lipases on the Polyester-Nanoparticles

Abstract:

Enzymatic degradation tests of polymer in form of nanoparticle (NP) were used to study the biodegradation of two different types of polymers polytetramethylene adipitate (SP4/6) and polybutylene isophthalate (PBI) by two commercially available lipases. The two lipases, which are from the yeast Candida cylindracea (CcL) and Pseudomonas species (PsL) respectively, exhibited sufficient degradation activities both for the aliphatic model polyester SP4/6 and the aromatic model polyester PBI and the use of polyester NPs has dramatically shortened the duration of enzymatic degradation tests. It has also been noticed that the degradation percentage of the polyesters was in the range of 35-50%, probably due to the formation of low molecular weight intermediates that are not accessible to the enzymes. Since biodegradation of polymers is a surface process, the adsorption of lipases on the surface of polyester NPs may play an important role. In order to gain some insights into the adsorption process of enzymes on polymer NPs, the adsorption of CcL and PsL lipases on two hardly degradable polyesters polybutylene terephthalate (PBT) and polyethylene terephthalate (PET) was investigated in this work. The adsorption of lipases on these polyester NPs showed a fast kinetic. Langmuir isotherms were found to be generally suitable to describe the adsorption of lipases on polyester NPs, especially at low lipase concentration under the experimental conditions. However, significant derivations from Langmuir isotherms were observed at high lipase concentrations.

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