Enzymatic Degradation Of PBS/PLA Blends And Its Application In The Construction Of Porous Materials

Poly(butylene succinate)(PBS) is a commercialized,biodegradable and aliphatic polyesters.PBS is widely used in packaging,biomedical industry,and other related fields because of its excellent biocompatibility,thermal,mechanical,and processing properties.However,PBS still has significant limitations,such as low tensile strength and low stiffness.Poly(lactic acid)(PLA) is a biodegradable polyester with high mechanical strength,thermal plasticity,and biocompatibility.PLA is still limited in the industrial applications due to its brittleness and slow crystallization rate.The blends obtained by the melt blending of PBS and PLA can improve the above problems.Selective enzymatic degradation of PBS/PLA blends can be used to prepare polymer porous materials.The polymer porous material prepared by enzymatic degradation is free of porogen and organic solvent.It makes it possible to be further applied in the field of biomedicine.In this work,PBS and PLA were melt-blended in different proportions and selectively degraded by cutinase and proteinase K,respectively.The selective enzymatic degradation process was systematically analyzed via scanning electron microscopy(SEM),attenuated total reflection fourier-transform infrared spectroscopy(ATR-FTIR),powder X-ray diffraction(XRD),and differential scanning calorimetry(DSC).The results of the weight loss of PBS/PLA blends degraded by cutinase and proteinase K suggested that PLA hindered the cutinase-catalyzed degradation of PBS,and the addition of PBS in the blends accelerated the degradation of PLA within a specific PBS/PLA ratio.The characterization of PBS/PLA blends after degradation showed that selective enzymatic degradation could not completely degrade PBS or PLA component.The porous materials were further characterized with respect to their pore morphology,pore size,porosity,and hydrophilicity.The biodegradation in vitro and in vivo and the biocompatibility in vivo of the porous materials were also assayed.The pore size of the prepared porous materials could be controlled by changing the PBS to PLA ratio and the degradation time.Increasing the PBS composition of PBS/PLA blends from 40 wt% to 50 wt%,the average pore diameter significantly increased from 6.91 μm to 120 μm,porosity improved from 81.52% to 96.90%,and the contact angle decreased from 81.08° to 46.56°.In the assay of the degradation in vitro,PBS-based porous materials exhibited a good corrosion resistance in simulated body fluid and the PLA-based porous materials were hydrolyzed.Subcutaneous implantation of the porous materials did not cause an intense inflammatory response,indicating good biocompatibility.The results of hematoxylin and eosin and Masson’s trichrome staining assays displayed that the porous materials promote chondrocyte production.Therefore,the porous materials prepared have potential applications as implants for tissue engineering.