Recyclable β-Glucosidase by One-Pot Encapsulation with Cu-MOFs for Enhanced Hydrolysis of Cellulose to Glucose

Enhancing the stability and reusability of enzymes by encapsulating them within a powerful class of porous materials termed metal-organic frameworks (MOFs) has been demonstrated by recent studies. However, in all of these reports, the stability of MOFs under acidic conditions was a major issue for enzymes with catalytic activity at low pH. The objective of this study is to encapsulate the beta-glucosidase (beta-G) into the Cu-MOF due to its acidic stability, using a coprecipitation approach. Indeed, the as-prepared beta-G@Cu(PABA) biocomposite with high encapsulation efficiency exhibited enhanced resistance to acidic and thermal conditions as well as organic solvents. Importantly, the beta-G@Cu(PABA) biocomposite showed superior reusability, retaining 90% of activity even after 10 cycles. Using the hydrolysis of carboxymethylcellulose (CMC) as a mode, the mixture of beta-G@Cu(PABA) biocomposite and coimmobilized cellulase afforded 98% glucose yield, which was twofold enhancement when compared with coimmobilized cellulose alone. The beta-G@Cu(PABA) biocomposite and coimmobilized cellulase could been easily recovered and recycled to still retain 70% productivity in the eight cycles for hydrolyzing CMC. This discovery for the first time highlights the potential of Cu-MOF in preserving the enzymes under acidic conditions. The developed beta-G@Cu(PABA) biocomposite by coprecipitation approach affords a valuable platform for enzyme-based industrial applications.