One-Pot Encapsulation of Enzymes in a Calcium Carboxylate Metal-Organic Framework for Improved Buffer Stability

Diverse metal-organic frameworks (MOFs) have been actively studied for enzyme encapsulation to enhance encapsulation efficiency (EE), retained enzymatic activity (REA), and stability. This study develops a biocompatible synthesis protocol for a MOF constructed from Ca²⁺ and 4,5-imidazoledicarboxylate ligand (termed CaIDC) in water at room temperature. This method enabled in situ, one-pot encapsulation of various enzymes, including bovine serum albumin (BSA), glucose oxidase (GOx), catalase (CAT), and esterase (EST). Compared to widely studied zeolitic imidazolate frameworks (ZIFs), CaIDC-based biocomposites demonstrated enhanced chemical robustness in phosphate buffer at pH 6.0 and 7.4. To optimize the synthesis process, a machine learning-assisted workflow incorporating Latin hypercube sampling (LHS) is developed for an efficient exploration of the entire synthesis space. As a model system, the optimized EST@CaIDC sample (EC19) exhibited EE, REA, and protein loading (P_loading) values of 28.7%, 20.1%, and 4.2 wt.%, respectively. In all, this study presents the development of a robust CaIDC-based platform for enzyme encapsulation and the implementation of an efficient ML-assisted optimization strategy, offering a pathway to advance enzyme encapsulation technologies with enhanced catalytic performance and sustainability.