Synthesis of paramylon ester-graft-PLA copolymers and its two-step enzymatic degradation by proteinase K and β-1,3-glucanase

Paramylon ester-graft-poly(lactic acid) (PLA) copolymers were synthesized by the ring opening polymerization of l-lactide with paramylon acetate (PaAc) samples having an degree substitution (DS) from 0.5 to 2.2 (PaAc-g-PLA) or propionate (PaPr) a DS 1.6 2.0 (PaPr-g-PLA). These exhibited thermoplasticity and some formed self-supporting melt-pressed films. Analyses annealed films using differential scanning calorimetry showed that their thermal properties varied PLA DS. The enzymatic degradation behaviors neat as well PaAc PaPr investigated treating these materials β-1,3-glucanase followed spectrometric analysis glucose levels in buffer solutions, prior investigation copolymers. data 9 wt% was obtained after 7 d also degraded β-1,3-glucanase. concentration liberated found decrease increased. Two-step tests subsequently carried out PaAc-g-PLA PaPr-g-PLA specimens. In first step, proteinase K applied degrade side-chains high performance liquid chromatography (HPLC) used assess release lactic acid. Both HPLC nuclear magnetic resonance (NMR) analyses established both specimens successfully degraded. second employed decompose remaining ester backbones. Monitoring backbones trials PaAc0.5-g-PLA PaAc1.0-g-PLAs results confirmed could be broken down via this two-step treatment, dependent on backbone. work show PaAc1.0-g-PLA is plastic material capable processing completely biodegradable.