Origin of Metal Cluster Tuning Enzyme Activity at the Bio-Nano Interface

Molecular Engineering and Morphology Control of Covalent Organic Frameworks for Enhancing Activity of Metal-Enzyme Cascade Catalysis

Metal-enzyme integrated catalysts (MEICs) that combine metal and enzyme offer great potential for sustainable chemoenzymatic cascade catalysis. However, rational design and construction of optimal microenvironments and accessible active sites for metal and enzyme in individual nanostructures are necessary but still challenging. Herein, Pd nanoparticles (NPs) and Candida antarctica lipase B (CALB) are co-immobilized into the pores and surfaces of covalent organic frameworks (COFs) with tunable functional groups, affording Pd/COF-X/CALB (X = ONa, OH, OMe) MEICs. This strategy can regulate the microenvironment around Pd NPs and CALB, and their interactions with substrates. As a result, the activity of the COF-based MEICs in catalyzing dynamic kinetic resolution of primary amines is enhanced and followed COF-OMe > COF-OH > COF-ONa. The experimental and simulation results demonstrated that functional groups of COFs modulated the conformation of CALB, the electronic states of Pd NPs, and the affinity of the integrated catalysts to the substrate, which contributed to the improvement of the catalytic activity of MEICs. Further, the MEICs are prepared using COF with hollow structure as support material, which increased accessible active sites and mass transfer efficiency, thus improving catalytic performance. This work provides a blueprint for rational design and preparation of highly active MEICs.

Enzyme-Polymer Conjugates for Tuning, Enhancing, and Expanding Biocatalytic Activity

Combining polymers with functional proteins is an approach that has brought several successful stories in the field of biomedicine with PEGylated therapeutic proteins. The latest advances in polymer chemistry have facilitated the expansion of protein-polymer hybrids to other research areas such as biocatalysis. Polymers can impart stability and novel functionalities to the enzyme of interest, thereby improving the catalytic performance of a given reaction. In this review, we have revisited the main methodologies currently used for the synthesis of enzyme-polymer hybrids, unveiling the interplay between the configuration and the composition of the assembled structure and the eventual traits of the hybrid. Finally, the latest advances, such as the assembly of polymer-based chemoenzymatic nanoreactors and the use of deep learning methodologies to achieve the most suitable polymer compositions for catalysis, are discussed.

Assessment of Enzyme Functionality at Metal-Organic Framework Interfaces Developed through Molecular Simulations

The catalytic efficiency and unrivaled selectivity with which enzymes convert substrates to products have been tapped for widespread chemical transformations within biomedical technology, biofuel production, gas sensing, and the upgrading of commodity chemicals, just to name a few. However, the feasibility of enzymes implementation is challenged by the lack of reusability and loss of native catalytic activity due to the irreversible biocatalyst denaturation at high temperatures and in the presence of industrial solvents. Enzyme immobilization, a prerequisite for enzyme reusability, offers controllable strategies for increased functional viability of the biocatalyst in a synthetic environment. Herein we used molecular dynamics (MD) simulations and probed the noncovalent interactions between model enzymes of technological interest, i.e., carbonic anhydrase (CA) and myeloperoxidase (MPO), with selected metal-organic frameworks (MOFs; MIL-160 and ZIF-8) of proven industrial implementation. We found that the CA and MPO can bind to MIL-160 at optimal binding energies of 201 and 501 kJ mol^-1, respectively, that are strongly influenced by the increased incidence of hydrogen bonding between enzymes and the frameworks. The free energy of binding of enzymes to ZIF-8, on the other hand, was found to be less strongly influenced by hydrogen bonding networks relative to the occurrence of hydrophobic-hydrophobic interactions that yielded 106 kJ mol^-1 for CA and 201 kJ mol^-1 for MPO.

Surface functionalization of graphene nanosheet with poly (L-histidine) and its application in drug delivery: covalent vs non-covalent approaches

Nowadays, nanomaterials are increasingly being used as drug carriers in the treatment of different types of cancers. As a result, these applications make them attractive to researchers dealing with diagnosis and biomarkers discovery of the disease. In this study, the adsorption behavior of gemcitabine (GMC) on graphene nanosheet (GNS), in the presence and absence of Poly (L-histidine) (PLH) polymer is discussed using molecular dynamics (MD) simulation. The MD results revealed an increase in the efficiency and targeting of the drug when the polymer is covalently attached to the graphene substrate. In addition, the metadynamics simulation to investigate the effects of PLH on the adsorption capacity of the GNS, and explore the adsorption/desorption process of GMC on pristine and PLH- grafted GNS is performed. The metadynamics calculations showed that the amount of free energy of the drug in acidic conditions is higher (- 281.26 kJ/mol) than the free energy in neutral conditions (- 346.24 kJ/mol). Consequently, the PLH polymer may not only help drug adsorption but can also help in drug desorption in lower pH environments. Based on these findings, it can be said that covalent polymer bonding not only can help in the formation of a targeted drug delivery system but also can increase the adsorption capacity of the substrate.