Improvements of lipase performance in high-viscosity system by immobilization onto a novel kind of poly(methylmethacrylate-co-divinylbenzene) encapsulated porous magnetic microsphere carrier

Biochemical Study of Bacillus stearothermophilus Immobilized Lipase for Oily Wastewater Treatment

Traditional wastewater treatments involve expensive mechanical and physiochemical methods, so researchers have been developing cost-effective, sustainable technologies that use enzymes to produce higher quality effluents and recover more energy and nutrients from wastewater. A thermostable, alkaline, and solvent-tolerant lipase was partially purified from thermophilic Bacillus stearothermophilus. The lipase displayed maximum activity at 50 °C and pH 11.0 and catalyzed both short- and long-chain triacylglycerols at similar rates. B. stearothermophilus lipase also exhibited high stability when incubated at 40 °C for 1 h with anionic and non-ionic surfactants. Studies show that thermostable enzymes can be improved through immobilization and modification of other reaction conditions. Therefore, B. stearothermophilus lipase was immobilized through adsorption on CaCO3, Celite 545, and silica gel with the CaCO3 support producing the best adsorption rate (89.33%). The optimal initial lipase activity was approximately 4500 U.g−1 after 60 min. Interestingly, 93% of the initial lipase activity was retained after six cycles, and almost 50% of the initial activity remained after 12 cycles. Furthermore, immobilization improved storage stability with 98.85% of the initial lipase activity retained after 60 days of storage at 4 °C. The biochemical characteristics of immobilized lipase shifted toward a slightly alkaline region, reaching maximum activity at pH 12. The optimal temperature of immobilized lipase was 60 °C. Immobilization also improved enzymatic stability by widening the pH range from 5–9 (for free lipase) to 4–11, and thermostability by reaching 65 °C. The application of immobilized lipase in wastewater treatment was observed through oil layer biodegradation. Notably, treating wastewater for 10 days with immobilized lipase almost removed the chemical oxygen demand (COD) from 1950.1 down to 4.04 mg.L−1. Similarly, lipid content was almost removed from 15,500 ± 546 mg.L−1 down to 12 mg.L−1. All results highlight the potential value of CaCO3-immobilized lipase as an effective biocatalyst for hydrolyzing wastewater.

CNS-Targeting Therapies for Lysosomal Storage Diseases: Current Advances and Challenges

During the past decades, several therapeutic approaches have been developed and made rapidly available for many patients afflicted with lysosomal storage disorders (LSDs), inborn organelle disorders with broad clinical manifestations secondary to the progressive accumulation of undegraded macromolecules within lysosomes. These conditions are individually rare, but, collectively, their incidence ranges from 1 in 2,315 to 7,700 live-births. Most LSDs are manifested by neurological symptoms or signs, including developmental delay, seizures, acroparesthesia, motor weakness, and extrapyramidal signs. The chronic and later-onset clinical forms are at one end of the continuum spectrum and are characterized by a subtle and slow progression of neurological symptoms. Due to its inherent physiological properties, unfortunately, the blood-brain barrier (BBB) constitutes a significant obstacle for current and upcoming therapies to achieve the central nervous system (CNS) and treat neurological problems so prevalent in these conditions. To circumvent this limitation, several strategies have been developed to make the therapeutic agent achieve the CNS. This narrative will provide an overview of current therapeutic strategies under development to permeate the BBB, and address and unmet need for treatment of the progressive neurological manifestations, which are so prevalent in these inherited lysosomal disorders.

Immobilization of lipase on the modified magnetic diatomite earth for effective methyl esterification of isoamyl alcohol to synthesize banana flavor

The present study was designed to propose a simple, cost-effective, and efficient method for the preparation of a biocompatible composite made from magnetic diatomaceous earth (mDE) coated by aminopropyltriethoxysilane (APTES) and its application for immobilization of porcine pancreatic lipase (PPL). The produced mDE-APTES was instrumentally characterized and the obtained results of FTIR analysis and scanning electron microscopy equipped by energy-dispersive X-ray spectroscopy (SEM-EDS) showed successful coating of APTES on mDE surface. PPL was then immobilized onto mDE to obtain the biocatalyst of PPL@mDE (immobilization yield and efficiency of 78.0 ± 0.3% and 80.1 ± 0.6, respectively) and the presence of enzyme was confirmed by EDS method. The attained results of the reusability of PPL@mDE revealed that 57% of the initial activity was retained after 11 cycles of biocatalyst application. PPL@mDE demonstrated higher storage stability than the free enzyme at 4 °C, 25 °C, and 37 °C. The apparent K m (2.35 ± 0.12 mM) and V max (13.01 ± 0.64 µmol/min) values for the immobilized enzyme were considerably altered compared to those of the free enzyme (p > 0.05). PPL@mDE was subsequently employed for the synthesis of banana flavor (isoamyl acetate) in n-hexane, which yields an esterification percentage of 100 at 37 °C after 3 h. However, it merits further investigations to find out about large-scale application of the as-synthesized biocatalyst for esterification.

Three-dimensional ordered macroporous magnetic photonic crystal microspheres for enrichment and detection of mycotoxins (I): Droplet-based microfluidic self-assembly synthesis

Ordered porous materials are attracting enormous attention due to their uniform pore structures, particularly the magnetic photonic crystal microspheres (PCMs) which not only possess unique photonic crystal structure but also can achieve separation easily based on magnet. Here, a two-phase microfluidic self-assembly synthetic system was established simply and employed for the preparation of three dimensional PCMs (3DPCMs) by using the emulsion droplet approach. One phase (dispersed phase) was an aqueous emulsion containing Fe₃O₄, silica (SiO₂) and polystyrene (PS) nanoparticles; another phase (continuous phase) was pure silicone oil. The droplets were formed by introducing the dispersed phase into the continuous phase through a tee valve. By heating the droplets, the water would evaporate and the nanoparticles would finally assemble into solid microspheres, which could be changed into macroporous 3DPCMs after removal of the PS nanoparticles by calcination. The contents and particle sizes of Fe₃O₄, SiO₂ and PS nanoparticles in the dispersed phase were investigated in detail and optimized to prepare macroporous magnetic 3DPCMs with high quality. The morphologies, surface crystal structure, magnetic property, particle size distribution, specific surface area and pore size of the macroporous magnetic 3DPCMs were characterized. The expected 3DPCM displayed regular and uniform photonic crystal structure, narrow particle size distribution and strong magnetic property. The macroporous magnetic 3DPCMs grafted with vomitoxin (DON)-antibodies could be applied for selective enrichment of DON in real samples.

The Immobilization of Lipases on Porous Support by Adsorption and Hydrophobic Interaction Method

Four major enzymes commonly used in the market are lipases, proteases, amylases, and cellulases. For instance, in both academic and industrial levels, microbial lipases have been well studied for industrial and biotechnological applications compared to others. Immobilization is done to minimize the cost. The improvement of enzyme properties enables the reusability of enzymes and facilitates enzymes used in a continuous process. Immobilized enzymes are enzymes physically confined in a particularly defined region with retention to their catalytic activities. Immobilized enzymes can be used repeatedly compared to free enzymes, which are unable to catalyze reactions continuously in the system. Immobilization also provides a higher pH value and thermal stability for enzymes toward synthesis. The main parameter influencing the immobilization is the support used to immobilize the enzyme. The support should have a large surface area, high rigidity, suitable shape and particle size, reusability, and resistance to microbial attachment, which will enhance the stability of the enzyme. The diffusion of the substrate in the carrier is more favorable on hydrophobic supports instead of hydrophilic supports. The methods used for enzyme immobilization also play a crucial role in immobilization performance. The combination of immobilization methods will increase the binding force between enzymes and the support, thus reducing the leakage of the enzymes from the support. The adsorption of lipase on a hydrophobic support causes the interfacial activation of lipase during immobilization. The adsorption method also causes less or no change in enzyme conformation, especially on the active site of the enzyme. Thus, this method is the most used in the immobilization process for industrial applications.

Three-dimensional ordered macroporous magnetic photonic crystal microspheres for enrichment and detection of mycotoxins (II): The application in liquid chromatography with fluorescence detector for mycotoxins

Enrichment, separation and purification are very important to accurately analyze mycotoxins in complicated samples. In the work, we developed a new enrichment, purification and high-performance liquid chromatography combined with fluorescence detector (HPLC-FLD) for aflatoxins B₁ (AFB₁), ochratoxin A (OTA) and Zearalenone (ZEN) assay using the macroporous magnetic 3D photonic crystal microspheres (3DPCMs). The conditions of enrichment and purification for mycotoxins have been optimized, which are as follows: pore size of 3DPCMs at 280 nm, 1:1 methanol:acetonitrile (v/v) as eluent, antibody concentrations at 60 µg/mL,60 µg/mL and 120 µg/mL for OTA, AFB₁ and ZEN, respectively. The recovery rates in the rice, wheat and corn samples range from 70.01% to 100.12% and the relative standard deviation (RSD) range from 0.45% to 7.09%. The recovery rates used 3DPCMs are almost tenfold higher than that used non-macroporous PCMs in the same conditions. The developed method is simple, rapid (time including enrichment, purification and detection <2 h) and only requires small volume reagents (≤200 µL).

Enzyme Immobilization on Metal-Organic Framework (MOF): Effects on Thermostability and Function

MOFs are porous materials with adjustable porosity ensuing a tenable surface area and stability. MOFs consist of metal containing joint where organic ligands are linked with coordination bonding rendering a unique architecture favouring the diverse applications in attachment of enzymes, Chemical catalysis, Gases storage and separation, biomedicals. In the past few years immobilization of soluble enzymes on/in MOF has been the topic of interest for scientists working in diverse field. The activity of enzyme, reusability, storage, chemical and thermal stability, affinity with substrate can be greatly improved by immobilizing of enzyme on MOFs. Along with improvement in enzymes properties, the high loading of enzyme is also observed while using MOFs as immobilization support. In this review a detail study of immobilization on/in Metalorganic Frameworks (MOFs) have been described. Furthermore, strategies for the enzyme immobilization on MOFs and resulting in improved catalytic performance of immobilized enzymes have been reported.

Co-Immobilization of Enzymes and Magnetic Nanoparticles by Metal-Nucleotide Hydrogelnanofibers for Improving Stability and Recycling

In this paper we report a facile method for preparing co-immobilized enzyme and magnetic nanoparticles (MNPs) using metal coordinated hydrogel nanofibers. Candida rugosa lipase (CRL) was selected as guest protein. For good aqueous dispersity, low price and other unique properties, citric acid-modified magnetic iron oxide nanoparticles (CA-Fe₃O₄ NPs) have been widely used for immobilizing enzymes. As a result, the relative activity of CA-Fe₃O₄@Zn/AMP nanofiber-immobilized CRL increased by 8-fold at pH 10.0 and nearly 1-fold in a 50 °C water bath after 30 min, compared to free CRL. Moreover, the immobilized CRL had excellent long-term storage stability (nearly 80% releative activity after storage for 13 days). This work indicated that metal-nucleotide nanofibers could efficiently co-immobilize enzymes and MNPs simultaneously, and improve the stability of biocatalysts.

Immobilization of Lipase from Pseudomonas fluorescens on Porous Polyurea and Its Application in Kinetic Resolution of Racemic 1-Phenylethanol

A porous polyurea (PPU) was prepared through a simple protocol by reacting toluene diisocyanate with water in binary solvent of water-acetone. Its amine group was determined through spectrophotometric absorbance based on its iminization with p-nitrobenzaldehyde amines. PPU was then used as a novel polymer support for enzyme immobilization, through activation by glutaraldehyde followed by immobilization of an enzyme, lipase from Pseudomonas fluorescens (PFL), via covalent bonding with the amine groups of lipase molecules. Influences of glutaraldehyde and enzyme concentration and pH in the process were studied. The results revealed that the activity of the immobilized PFL reached a maximum at GA concentration of 0.17 mol/L and at pH 8. Immobilization rate of 60% or higher for PFL was obtained under optimized condition with an enzyme activity of 283 U/mg. The porous structure of PPU, prior to and after GA activation and PFL immobilization, was characterized. The activity of the immobilized PFL at different temperature and pH and its stability at 40 °C as well as its reusability were tested. The immobilized enzyme was finally used as enantioselective catalyst in kinetic resolution of racemic 1-phenylethanol (1-PEOH), and its performance compared with the free PFL. The results demonstrate that the enzyme activity and stability were greatly improved for the immobilized PFL, and highly pure enantiomers from racemic 1-PEOH were effectively achieved using the immobilized PFL. Noticeable deactivation of PFL in the resolution was observed by acetaldehyde in situ formed. In addition, the immobilized PFL was readily recovered from the reaction system for reuse. A total of 73% of the initial activity was retained after 5 repeated reuse cycles. This work provides a novel route to preparation of a polyurea porous material and its enzyme immobilization, leading to a novel type of immobilized enzyme for efficient kinetic resolution of racemic molecules.

Facile preparation of porous magnetic polydopamine microspheres through an inverse replication strategy for efficient enzyme immobilization

Porous microspheres composed of biocompatible dopamine and magnetic Fe₃O₄ nanoparticles were fabricated by inverse replication of CaCO₃ templates.

Micron-sized flower-like Fe3O4@GMA magnetic porous microspheres for lipase immobilization

Flower-like Fe₃O₄ microspheres prepared by a fast solvothermal method were selected to fabricate micron-sized Fe₃O₄@glycidyl methacrylate (GMA) magnetic porous microspheres.

Activity and stability of urease entrapped in thermosensitive poly(N-isopropylacrylamide-co-poly(ethyleneglycol)-methacrylate) hydrogel

Urease was entrapped in thermally responsive poly(N-isopropylacrylamide-co-poly(ethyleneglycol)-methacrylate), p[NIPAM-p(PEG)-MA], copolymer hydrogels. The copolymer membrane shows temperature-responsive properties similar to conventional p(NIPAM) hydrogels, which reversibly swell below and de-swell above the lower critical solution temperature of p(NIPAM) hydrogel at around 32 °C. The retained activities of the entrapped urease (in p[NIPAM-p(PEG)-MA]-4 hydrogels) were between 83 and 53% compared to that of the same quantity of free enzyme. Due to the thermo-responsive character of the hydrogel matrix, the maximum activity was achieved at around 25 °C with the immobilized urease. Optimum pH was the same for both free and entrapped enzyme. Operational, thermal and storage stabilities of the enzyme were found to increase with entrapment of urease in the thermoresponsive hydrogel matrixes. As for reusability, the immobilized urease retained 89% of its activity after ten repeated uses.