Lipases have been widely used as biocatalysts for numerous biotechnological applications. In an earlier paper, we presented experimental results showing significantly enhanced activity of the Lip2 lipase immobilized on carbon nanotubes (CNTs). In this work, to elucidate the activation mechanism of the lipase, we present an atomic resolution analysis of the lid domain motion of the Lip2 lipase upon immobilization by simulating the protein dynamics. The Lip2 lipase interacts with the CNT at a local site. However, the effects of that interaction are propagated to a remote lid subdomain. The chain of events initiated by the interaction provide the basis for a fundamental understanding of the lid opening mechanism. We identify the structural path followed by co-operative interactions that originate at the interaction site. In addition, salt bridge and hydrogen bonding interactions, which contribute to the propagation of interaction effects to distal regions, are also identified. The present study provides a plausible molecular model for understanding the mechanisms of lid opening of the immobilized lipase. The importance of the structural characteristics of the lipase upon immobilization on the CNT suggests that enzymes may be engineered to be site-specifically immobilized onto a hydrophobic support, such as carbon nanotubes, to achieve enhanced enzymatic activity.

This work presented a novel core-shell MnO₂@m-SiO₂ for catalyzing the removal of dyes from wastewater. MnO₂ nanorods were sequentially coated with polydopamine (PDA) and polyethyleneimine (PEI) forming MnO₂@PDA-PEI. By taking advantage of the positively charged amine groups, MnO₂@PDA-PEI was further silicificated, forming MnO₂@PDA-PEI-SiO₂. After calcination, the composite MnO₂@m-SiO₂ was finally obtained. MnO₂ nanorod is the core and mesoporous SiO₂ (m-SiO₂) is the shell. MnO₂@m-SiO₂ has been used to degrade a model dye Rhodamine B (RhB). The shell m-SiO₂ functioned to adsorb/enrich and transfer RhB, and the core MnO₂ nanorods oxidized RhB. Thus, MnO₂@m-SiO₂ combines multiple functions together. Experimental results demonstrated that MnO₂@m-SiO₂ exhibited a much higher efficiency for degradation of RhB than MnO₂. The RhB decoloration and degradation efficiencies were 98.7% and 84.9%, respectively. Consecutive use of MnO₂@m-SiO₂ has demonstrated that MnO₂@m-SiO₂ can be used to catalyze multiple cycles of RhB degradation. After six cycles of reuse of MnO₂@m-SiO₂, the RhB decoloration and degradation efficiencies were 98.2% and 71.1%, respectively.

2,5-Furandicarboxylic acid (FDCA) is a value added chemical that can be used as a polymer building block for the synthesis of biobased polymers.