Studies On Enzymatic Degradation Of Polymer Nanoparticles And Adsorption Mechanism Of Enzymes On Nanoparticles

Enzymatic degradation tests of polymer in the form of nanoparticle as a new toolwere used to evaluate biodegradability of aromatic polymer, study biodegradationof polymer, which is characterized by good reproducibility, the shortening of testduration. In the present paper, the pH-stat system was used to determinebiodegradation of polyester-nanoparticle (NP) by enzymes. First the experimentalcondition was optimized. Second the test duration of enzymatic degradation ofpolymer NPs was assessed. The biodegradability of several polyesters wasevaluated and the correlation of biodegradability and structure was discussedsimply. Then the two kinds of polyesters were selected as model ones, aliphaticpolyester SP4/6 and aromatic polyester PBI. Their enzymatic degradation ofapplying lipases (CcL, PsL) was carried out. CcL-SP4/6 and PsL-PBI were chosento study kinetics of enzymatic degradation and the dependence of degradation rateof polyester NPs on lipase load was obtained. It has been also noticed that thedegradation percentage of polyester with lipase was not 100%, which is unlikeother hydrolases. A simple heterogeneous kinetic model of enzymatic degradationof synthesized polyesters was developed. Studies on TfH were also conducted. It is well known that biodegradation of polymer is a surface process. Thereforeadsorption of lipases on aromatic polyester NPs, which were slowly biodegradableand not degraded during adsorption experiments, was also studied in order to havesome insights into adsorption mechanism during biodegradation. The adsorption ofenzymes on polyester NPs showed a fast kinetic. Langmuir isotherms were used todescribe the adsorption phenomena of enzymes on polyester NPs at lower enzymeconcentration and adsorption parameters such as adsorption coefficient andmaximum adsorption capacity have been evaluated. CcL and PsL both exhibitedstronger affinity with polyester of relatively lower hydrophobicity. It seems thathydrophobic interaction, which is not relatively more important, together withother interactions at the interface determine the adsorption of lipase on polyesterNPs under experimental conditions. Adsorption of TfH on PBT was also studiedand compared with lipases on PBT.