Preparation and Comparison of Hydrolase-Coated Plastics

Abstract

Polypropylene and polyethylene were coated with alpha-Chymotrypsin (a-CT) or subtilisin Carlsberg (SubC) or Burkholderia cepacia lipase (lipase BC) by different immobilization procedures, such as physical adsorption and covalent linking. This latter procedure was based on the chemical functionalization of the plastic surface by oxygen gas plasma treatment. Immobilization of the enzyme was carried out by using as cross-linking agent i) glutaraldehyde (GA) or ii) N'-diisopropylcarbodiimide (DIC) and N-hydroxysuccinimide (NHS). The effects of duration of the plasma treatment and the type of the immobilization procedure on the transesterification activity of the enzyme were investigated. In general polypropylene resulted a better support than polyethylene. Moreover, a-CT showed higher transesterification activity when immobilized with GA, while for SubC, DIC and NHS were better cross-linking agents than GA. No activity was observed with these enzymes when immobilization was carried out by physical adsorption. On the contrary, lipase BC immobilized by physical adsorption was even more active than the free enzyme. Concerning thermal stability, immobilized SubC was less stable than the free enzyme. Overall, these results show that plastics endowed with biocatalytic properties could be obtained by simple immobilization protocols and that optimal immobilization conditions depend on the type of starting plastic, plasma treatment, cross-linking method, and the nature of the enzyme.

α-Chymotrypsin Immobilized on a Low-Density Polyethylene Surface Successfully Weakens Escherichia coli Biofilm Formation

“…The possibility to link enzymes to plastics (e.g., polypropylene and polyethylene) was previously shown by our team [24]. The procedure indicates that the preventive plasma treatment of the surface is crucial for providing the plastic surface with functional groups exploitable for the covalent binding of the enzyme to the surface by glutaraldehyde (GA).…”

“…Among others (e.g., subtilisin Carlsberg from Bacillus licheniformis , lipase from Burkholderia cepacia or pectinase from Aspergillus niger ), α-CT was preferred as, in a previous work by these authors, this enzyme showed the highest transesterification activity once immobilized with GA [24,30]. Notably, the same authors observed an increase in the catalytic activity of α-CT after treatment with GA [31].…”

“…This is especially useful in those fields where chemical contamination in the final product must be avoided for safety reasons, e.g., in food contact processing surfaces [41]. In addition, immobilization enhances the enzyme stability under both storage and operational conditions, e.g., by increasing its thermal stability, and therefore making it more attractive for diverse applications, especially when surfaces are subjected to harsh reaction conditions [24,31,42]. Recently, Spadoni-Andreani et al [37] covalently linked α-CT on polypropylene, thus providing a new material able to preserve the surface from Candida albicans colonization.…”

Improvement of Aspergillus flavus saponin hydrolase thermal stability and productivity via immobilization on a novel carrier based on sugarcane bagasse

“…A relatively high percentage of immobilized enzyme was also obtained using SBC activated via DIC/NHS method (37.1%). The chemical modification of SBC by addition of DIC to buffered (MES, pH 3.5) SBC and in the presence of NHS generates succynimidyl esters with carboxyl group of residual lignin and hemicellulose supposed to be present in the SCB after acid-base treatment, which covalently linked with amino groups of enzyme through amide linkage [ 23 , 17 ]. In general, the values of the covalently immobilized enzyme on carriers activated by other methods (GA or PI) were lower.…”

“… Activation of the carrier by DIC and NHS. This was carried out using two different procedures [ 17 ]. In the first case, carriers (0.5 g each) were immersed in 5 ml of 0.1 M, pH 3.5 MES buffer and dried at 40 °C under vacuum.…”