Lipase Immobilized on a Novel Rigid-Flexible Dendrimer-Grafted Hierarchically Porous Magnetic Microspheres for Effective Resolution of (R,S)-1-Phenylethanol

A Synergetic Pore Compartmentalization and Hydrophobization Strategy for Synchronously Boosting the Stability and Activity of Enzyme

Spatial immobilization of fragile enzymes using a nanocarrier is an efficient means to design heterogeneous biocatalysts, presenting superior stability and recyclability to pristine enzymes. An immobilized enzyme, however, usually compromises its catalytic activity because of inevasible mass transfer issues and the unfavorable conformation changes in a confined environment. Here, we describe a synergetic metal-organic framework pore-engineering strategy to trap lipase (an important hydrolase), which confers lipase-boosted stability and activity simultaneously. The hierarchically porous NU-1003, featuring interconnected mesopore and micropore channels, is precisely modified by chain-adjustable fatty acids on its mesopore channel, into which lipase is trapped. The interconnected pore structure ensures efficient communication between trapped lipase and exterior media, while the fatty acid-mediated hydrophobic pore can activate the opening conformation of lipase by interfacial interaction. Such dual pore compartmentalization and hydrophobization activation effects render the catalytic center of trapped lipase highly accessible, resulting in 1.57-fold and 2.46-fold activities as native lipase on ester hydrolysis and enantioselective catalysis. In addition, the feasibility of these heterogeneous biocatalysts for kinetic resolution of enantiomer is also validated, showing much higher efficiency than native lipase.

Construction of a Novel Lipase Catalytic System Based on Hybrid Membranes with Interwoven Electrospun Polyacrylic Acid and Polyvinyl Pyrrolidone Gel Fibers

Efficient lipase catalysis requires sufficient oil-water interface engineered through structural design. Inspired by the architectural features of fabrics, a novel lipase-membrane catalytic system with interwoven polyacrylic acid (PAA) gel fibers and polyvinyl pyrrolidone (PVP) gel fibers was developed in this study by using double-needle electrospinning and gelation. It has been demonstrated that PAA/PVP hybrid gel fiber membranes (HGFMs) have a high swelling capacity for both water and oil phases, which created numerous discontinuous oil-water contact surface units in limited space of HGFMs, consequently forming effective interfacial catalytic systems. Volume competition between the water and oil phases suggests that balancing the proportions of these phases is very important for effective construction of oil-water interfaces and conditioning catalysis. Regulation of multiple factors of PAA/PVP HGFMs resulted in a catalytic efficiency of up to 2.1 times that of a macroscopic "oil-up/water-down" system (room temperature, pH = 7), and 2.9 times when three membranes are superimposed, as well as excellent pH and temperature stability. HGFMs were stacked to build a high-performing catalytic performance reactor. We expect that this study will be a beneficial exploration for expanding the lipase catalytic system.

Stabilization of enzymes via immobilization: Multipoint covalent attachment and other stabilization strategies

The use of enzymes in industrial processes requires the improvement of their features in many instances. Enzyme immobilization, a requirement to facilitate the recovery and reuse of these water-soluble catalysts, is one of the tools that researchers may utilize to improve many of their properties. This review is focused on how enzyme immobilization may improve enzyme stability. Starting from the stabilization effects that an enzyme may experience by the mere fact of being inside a solid particle, we detail other possibilities to stabilize enzymes: generation of favorable enzyme environments, prevention of enzyme subunit dissociation in multimeric enzymes, generation of more stable enzyme conformations, or enzyme rigidification via multipoint covalent attachment. In this last point, we will discuss the features of an "ideal" immobilization protocol to maximize the intensity of the enzyme-support interactions. The most interesting active groups in the support (glutaraldehyde, epoxide, glyoxyl and vinyl sulfone) will be also presented, discussing their main properties and uses. Some instances in which the number of enzyme-support bonds is not directly related to a higher stabilization will be also presented. Finally, the possibility of coupling site-directed mutagenesis or chemical modification to get a more intense multipoint covalent immobilization will be discussed.

Co-Immobilization of Rhizopus oryzae and Candida rugosa Lipases onto mMWCNTs@4-arm-PEG-NH2-A Novel Magnetic Nanotube-Polyethylene Glycol Amine Composite-And Its Applications for Biodiesel Production

This article describes the successful synthesis of a novel nanocomposite of superparamagnetic multi-walled nanotubes with a four-arm polyethylene glycol amine polymer (mMWCNTs@4-arm-PEG-NH2). This composite was then employed as a support for the covalent co-immobilization of Rhizopus oryzae and Candida rugosa lipases under appropriate conditions. The co-immobilized lipases (CIL-mMWCNTs@4-arm-PEG-NH2) exhibited maximum specific activity of 99.626U/mg protein, which was 34.5-fold superior to that of free ROL, and its thermal stability was greatly improved. Most significantly, CIL-mMWCNTs@4-arm-PEG-NH2 was used to prepare biodiesel from waste cooking oil under ultrasound conditions, and within 120 min, the biodiesel conversion rate reached 97.64%. This was due to the synergy effect between ROL and CRL and the ultrasound-assisted enzymatic process, resulting in an increased biodiesel yield in a short reaction time. Moreover, after ten reuse cycles, the co-immobilized lipases still retained a biodiesel yield of over 78.55%, exhibiting excellent operational stability that is attractive for practical applications. Consequently, the combined use of a novel designed carrier, the co-immobilized lipases with synergy effect, and the ultrasound-assisted enzymatic reaction exhibited potential prospects for future applications in biodiesel production and various industrial applications.

Magnetic Nanoparticle-Containing Supports as Carriers of Immobilized Enzymes: Key Factors Influencing the Biocatalyst Performance

In this short review (Perspective), we identify key features of the performance of biocatalysts developed by the immobilization of enzymes on the supports containing magnetic nanoparticles (NPs), analyzing the scientific literature for the last five years. A clear advantage of magnetic supports is their easy separation due to the magnetic attraction between magnetic NPs and an external magnetic field, facilitating the biocatalyst reuse. This allows for savings of materials and energy in the biocatalytic process. Commonly, magnetic NPs are isolated from enzymes either by polymers, silica, or some other protective layer. However, in those cases when iron oxide NPs are in close proximity to the enzyme, the biocatalyst may display a fascinating behavior, allowing for synergy of the performance due to the enzyme-like properties shown in iron oxides. Another important parameter which is discussed in this review is the magnetic support porosity, especially in hierarchical porous supports. In the case of comparatively large pores, which can freely accommodate enzyme molecules without jeopardizing their conformation, the enzyme surface ordering may create an optimal crowding on the support, enhancing the biocatalytic performance. Other factors such as surface-modifying agents or special enzyme reactor designs can be also influential in the performance of magnetic NP based immobilized enzymes.

Zr-based acid-stable nucleotide coordination polymers: An excellent platform for acidophilic enzymes immobilization

Acidophilic enzymes play an important role in special industrial catalytic reactions. In this work, we reported Zr-based acid-stable nucleotide coordination polymers (CPs) for efficiently improving acidophilic enzymes immobilization. Among all tested metal ions, the Zr⁴⁺/AMP CPs exhibited the highest acid stability and enzyme affinity. As a typical acidophilic enzyme, the immobilized Chloroperoxidase by Zr⁴⁺/AMP CPs displayed robust reusability in the asymmetric synthesis of modafinil, remained 95.7% of conversion rate and 99.1% enantiomeric excess (e.e.) value. This work displayed a novel acid-stable bioorganic and inorganic hybrid nanomaterial for acidophilic enzymes immobilization.

Improvement of biodiesel production from palm oil by co-immobilization of Thermomyces lanuginosa lipase and Candida antarctica lipase B: Optimization using response surface methodology

Candida antarctica lipase B (CALB) and Thermomyces lanuginose lipase (TLL) were co-immobilized on epoxy functionalized silica gel via an isocyanide-based multicomponent reaction. The immobilization process was carried out in water (pH 7) at 25 °C, rapidly (3 h) resulting in high immobilization yields (100%) with a loading of 10 mg enzyme/g support. The immobilized preparations were used to produce biodiesel by transesterification of palm oil. In an optimization study, response surface methodology (RSM) and central composite rotatable design (CCRD) methods were used to study the effect of five independent factors including temperature, methanol to oil ratio, t-butanol concentration and CALB:TLL ratio on the yield of biodiesel production. The optimum combinations for the reaction were CALB:TLL ratio (2.1:1), t-butanol (45 wt%), temperature (47 °C), methanol: oil ratio (2.3). This resulted in a FAME yield of 94%, very close to the predicted value of 98%.