Enzyme Immobilization on a Delignified Bamboo Scaffold as a Green Hierarchical Bioreactor

Enzymes immobilized on cellulose-based supports provide important applications because they are convenient, economical, and stable. In this paper, we report the application of delignified bamboo as a novel cellulose-based scaffold for enzyme immobilization and bamboo enzyme-based flow bioreactors, which can drastically improve the catalytic reaction and subsequent separation. The delignified bamboo provides a superior biobenign and hierarchically structured platform that can be conveniently derivatized to conjugate functional proteins with high loading capacity. With an optimized delignification process and a modified Schiff base-dependent conjugation method, we identified an efficient approach to immobilize enzymes on bamboo. In our system, generally ∼8 mg/m2·g–1 proteins can be immobilized on the delignified bamboo, which is significantly higher than that of the reported methods. The immobilized enzymes on bamboo showed sustained activity under ambient conditions, excellent reusability with 13 cycles, and high stability of more than 7 weeks of storage at 4 °C, which can be readily adapted in flow reactors for both single transformation and tandem catalysis. As an example, drugs of abuse in synthetic urine samples were analyzed in β-glucuronidase (BGU)-functionalized flow reactors in 0.1 M phosphate buffer, pH 7.4, at room temperature, the condition suitable for the bioanalysis. Our work demonstrates that the delignified bamboo can serve as a readily available support for enzyme immobilization and hierarchical bioreactor construction, which will potentially increase the robustness of enzymes in analytical and synthetical applications.