Enhanced Stability and Performance of Immobilized Lipase Using Hydrophobically Modified Single-Crystalline Ordered Macro–Microporous CuBTC as a Carrier Material

Single-crystalline ordered macro–microporous CuBTC (SOM–CuBTC) is a promising carrier for lipase immobilization due to enhanced mass transfer and stability toward fatty acids. However, the low yield per mass of the template during the preparation process and the water instability of the SOM–CuBTC carrier have posed significant limitations on its practical applications. In this study, we addressed these challenges by introducing a novel dual-solvent system consisting of dimethyl sulfoxide (DMSO) and ethanol to obtain a stable precursor solution with a concentration approximately 10 times higher than that in previous literature, yielding 21.4 mg of SOM–CuBTC per gram of the polystyrene template. However, the decomposition of SOM–CuBTC in an aqueous system of lipase immobilization was observed. We explored chemical vapor deposition and sol–gel methods for hydrophobic modification on SOM–CuBTC. SOM–CuBTC coated by hydrophobic polydimethylsiloxane (PDMS) via the sol–gel method possessed excellent chemical stability and exhibited great potential for lipase immobilization with a significant increase by 98.7% in the specific activity. The obtained immobilized lipase not only showed improved thermal stability and pH tolerance but also displayed excellent catalytic performance in the synthesis process of 1-oleoyl-2-palmitoyl-3-linoleoylglycerol (OPL) by acidolysis. This work reveals the great potential of SOM–CuBTC and provides new insights into the rational design of metal–organic frameworks for enzyme immobilization in extensive applications.