Enzymatic assay of hydroxybutyric acid monomer formation in poly(β-hydroxybutyrate) degradation studies

A novel method for monitoring the degradation of poly(β-hydroxybutyrate) based on the enzymatic assay of β-hydroxybutyrate (HBA) monomers has been developed. The method is particularly applicable to forms of the polymer, such as fibre and microcapsules, for which conventional surface and gravimetric monitoring techniques are not readily applicable. The method involves the use of enzyme HBA dehydrogenase in a reaction that converts nicotinamide adenine dinucleotide (NAD) to its reduced form (NADH). The conversion is associated with an increase in light absorbtion at 340 nm which thus serves to indicate the concentration of HBA monomer in the sample. The application of the methodology to the degradation of poly(β-hydroxybutyrate) gel spun fibres has been used to demonstrate its potential use as a quantitative monitoring technique in the study of the hydrolysis of this polymer.