Enzyme-Embedded Degradation of Poly(ε-caprolactone) using Lipase-Derived from Probiotic Lactobacillus plantarum

Abstract

Enzyme-embedded polymer degradation was reported to be an attractive alternative approach to the conventional surface pouring method for efficient degradation of polymers using fungal-derived enzyme Candida antarctica lipase B. Despite the enormous potential, this approach is still in its infancy. In the present study, a probiotic lipase obtained from Lactobacillus plantarum has been employed for the first time to study the enzyme-embedded polymer degradation approach using poly(ε-caprolactone) (PCL) as the semicrystalline polymer candidate. PCL films embedded with 2 to 8 wt % lipase are studied under static conditions for their enzymatic degradation up to 8 days of incubation. Thermogravimetric analyses (TGA) have shown a clear trend in decreasing thermal stability of the polymer with increasing lipase content and number of incubation days. Differential thermal analyses have revealed that the percentage crystallinity of the leftover PCL films increases with progress in enzymatic degradation because of the efficient action of lipase over the amorphous regions of the films. Thus, the higher lipase loading in the PCL matrix and more number of incubation days have resulted in higher percentage crystallinity in the leftover PCL films, which has further been corroborated by X-ray diffraction analyses. In a similar line, higher percentage mass loss of the PCL films has been observed with increased enzyme loading and number of incubation days. Field emission scanning electron microscopy (FE-SEM) has been employed to follow the surface and cross-sectional morphologies of the polymer films, which has revealed micron-scale pores on the surface as well as a bulk polymer matrix with progress in enzymatic polymer degradation. Additionally, FE-SEM studies have revealed the efficient enzyme-catalyzed hydrolysis of the polymer matrix in a three-dimensional fashion, which is unique to this approach. In addition to the first-time utility of a probiotic lipase for the embedded polymer degradation approach, the present work provides insight into the PCL degradation under static and ambient temperature conditions with no replenishment of enzymes.

Embedded Enzyme Nanoclusters Depolymerize Polyesters via Chain-End Mediated Processive Degradation

“…Control experiments using reverse micelle-encapsulated lipase at the same lipase loading stop degrading after ~40 % mass loss due to leaching, consistent with previous reports ( Fig. S5) (9,17).…”

“…However, the rate of surface erosion is so slow that even so called biodegradable plastics, such as poly(lactic acid) (PLA), are essentially non-degradable (4,16). Accelerated random chain scissions have been achieved when the enzyme was dispersed as large enzyme/surfactant clusters via reverse micelles; however, the reaction proceeds preferentially in the amorphous domain (17), resulting in enzyme leaching and the formation of highly crystalline microplastic particles (9). When enzymes are confined at the length scales comparable to polymer chain dimensions, the kinetics and pathways of enzymatic reaction may vary ( Fig.…”

Selective degradation of synthetic polymers through enzymes immobilized on nanocarriers

“…4(b)] that was significantly less when compared to PCL fiber mats incubated with SiO 2 -cutinase or Khan et al analyzed the change of the molecular weight of PCL samples after the degradation through lipase using gel permeation chromatography revealing a decrease in molecular weight. [35] This suggests that the PCL fibers are probably degraded to their monomers, caproic acid and caprolactone, and oligomers. Additionally, a set of particles was modified with both enzymes and degradation tests were performed to evaluate any possible cooperative effects.…”

Experimental Analysis of the Enzymatic Degradation of Polycaprolactone: Microcrystalline Cellulose Composites and Numerical Method for the Prediction of the Degraded Geometry

“…Regarding the FTIR spectra, it is possible to observe a decrease in the relative amount of amorphous phase in the degraded samples for both materials ( Table 2 ), as enzymatic degradation is known to start in these domains of the polymer bulk [ 42 ] and it is then extended to crystalline domains [ 10 ]. However, this reduction is not continuous through the duration of the experiment and the ratio is slightly increased between 24 h and 48 h (from 1.57 ± 0.14 to 1.66 ± 0.05 for PCL samples and from 1.52 ± 0.01 to 1.61 ± 0.05 for composite samples).…”