Ultrafast and Green Encapsulation of Enzymes in Biotitania Nanoparticles via Elastin-like Polypeptide-Mediated Biomimetic Mineralization

As green catalysts, enzymes will play more and more important roles in modern industry. However, their practical application still suffers from challenges such as high costs, low stability, and undesirable controllability. Enzyme immobilization is a promising pathway to address these issues. Herein, we propose a novel strategy for enzyme immobilization in biotitania using elastin-like polypeptide (ELP)-mediated titanification-based enzyme immobilization (EMTBEI). High purity (∼98%) of ELP[K5V4F-40] can be obtained through a green and convenient purification process. ELP-mediated titanification is performed at neutral pH and ambient temperature, enabling green enzyme immobilization. Interestingly, ultrafast immobilization of xylanase in biotitania nanoparticles is achieved with excellent immobilization efficiency (113.5%) and good activity recovery (61.3%). TEM and SEM analyses show that the biotitania-immobilized xylanase is solid and spherical. EDS, FT-IR, and release testing reveal that xylanase is immobilized in biotitania via encapsulation. Both ELP and xylanase concentration affect immobilization, and the optimal concentrations are 1.5 mmol/L and 3 IU/mg, respectively. Thermal and storage stabilities of xylanase are both significantly improved. Meanwhile, the biotitania-immobilized xylanase shows excellent reusability, as more than 95% of the initial activity remains after 10 reaction cycles. Collectively, EMTBEI is a green and ultrafast method for enzyme immobilization in titania with excellent immobilization efficiency and reusability, which may have great potential to prepare biotitania-immobilized enzymes for various applications, such as green biomanufacturing, environmental pollution remediation, and biomedical engineering.