Chemically modified alginate bead matrix for efficient adsorptive recovery of trypsin from fresh bovine pancreas

Different electrically charged proteins result in diverse transport behaviors of plastic particles with different surface charge in quartz sand

The influence of proteins on the transport and deposition behaviors of microplastics (MPs) in quartz sand was examined at both low (5 mM) and high ionic strength (25 mM) in NaCl solutions at pH 6. Carboxylate- and amine-modified polystyrene latex microspheres with size of 200 nm were employed as negatively (CMPs) and positively surface charged MPs (AMPs), respectively, while bovine serum albumin (BSA) and bovine trypsin were utilized as representative negatively and positively charged proteins, respectively. The results showed that for two examined protein concentrations (both 1 and 10 mg/L TOC) under both ionic strength conditions, the presence of BSA increased the transport of both CMPs and AMPs, while the presence of trypsin decreased the transport of CMPs yet increased the transport of AMPs in porous media. The mechanisms driving to the changed transport of MPs induced by two types of proteins were found to be different. Particularly, steric interaction induced by BSA corona adsorbed onto CMPs surface as well as the repel effects resulted from BSA suspending in solutions were found to contribute to the enhanced CMPs transport with BSA copresent in suspensions. The increased sizes and the decreased electrostatic repulsion of CMPs due to the adsorption of trypsin onto CMPs, together with the addition of extra deposition sites due to the adsorption of trypsin onto quartz sand drove to the decreased CMPs transport with trypsin copresent in suspensions. The increased electrostatic repulsion due to the adsorption of BSA onto AMPs surfaces caused the enhanced AMPs transport with BSA in solutions. While, the decreased electrostatic attraction of AMPs due to the adsorption of trypsin onto AMPs, as well as the competition of deposition sites due to the adsorption of trypsin onto quartz sand contributed to the increased AMPs transport with trypsin copresent in suspensions. The results showed that the presence of different types of proteins would induce different transport behaviors of microplastics with different surface charge in porous media. Since proteins are widely present in aquatic systems, to more accurately predict the fate and transport of MPs in natural environments, the effects and mechanisms of proteins on the transport of MPs should be considered.

Fabrication of Microporous Metal-Organic Frameworks in Uninterrupted Mesoporous Tunnels: Hierarchical Structure for Efficient Trypsin Immobilization and Stabilization

Hierarchically porous metal-organic frameworks (HP-MOFs) are promising in various applications. Most reported HP-MOFs are prepared based on the generation of mesopores in microporous frameworks, and the formed mesopores are connected by microporous channels, limiting the accessibility of mesopores for bulky molecules. A hierarchical structure is formed by constructing microporous MOFs in uninterrupted mesoporous tunnels. Using the confined space in as-prepared mesoporous silica, highly dispersed metal precursors for MOFs are coated on the internal surface of mesoporous tunnels. Ligand vapor-induced crystallization is employed to enable quantitative formation of MOFs in situ, in which sublimated ligands diffuse into mesoporous tunnels and react with metal precursors. The obtained hierarchically porous composites exhibit record-high adsorption capacity for the bulky molecule trypsin. The thermal and storage stability of trypsin is improved upon immobilization on the composites.