Optimization strategy for laccase immobilization on polyethylene terephthalate grafted with maleic anhydride electrospun nanofiber mat

Advanced applications in enzyme-induced electrospun nanofibers

Electrospun nanofibers, renowned for their high specific surface area, robust mechanical properties, and versatile chemical functionalities, offer a promising platform for enzyme immobilization. Over the past decade, significant strides have been made in developing enzyme-induced electrospun nanofibers (EIEN). This review systematically summarizes the advanced applications of EIEN which are fabricated using both non-specific immobilization methods including interfacial adsorption (direct adsorption, cross-linking, and covalent binding) and encapsulation, and specific immobilization techniques (coordination and affinity immobilization). Future research should prioritize optimizing immobilization techniques to achieve a balance between enzyme activity, stability, and cost-effectiveness, thereby facilitating the industrialization of EIEN. We elucidate the rationale behind various immobilization methods and their applications, such as wastewater treatment, biosensors, and biomedicine. We aim to provide guidelines for developing suitable EIEN immobilization techniques tailored to specific future applications.

An Alternative Approach to Plastic Recycling: Fabrication and Characterization of rPET/CA Nanofiber Carriers to Enhance Porcine Pancreatic Lipase Stability Properties

In response to the increasing demand for sustainable technologies, this study presents a novel approach to plastic recycling. In this study, a method was presented to produce nanofiber carriers by electrospinning using recycled poly(ethylene terephthalate) (rPET) obtained from wastewater bottles and cellulose acetate (CA). These carriers serve as a platform for immobilized porcine pancreatic lipase (PPL), aiming to enhance its stability. The production parameters for the rPET/CA nanofibers were found to be an rPET concentration of 15% (v/v), a CA concentration of 6% (v/v), an electrical voltage of 13 kV, a needle-collector distance of 18 cm, and an injection speed of 0.1 mL/h. The nanofiber structure and morphology were assessed by using attenuated total reflectance-infrared Fourier transform infrared (ATR-FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) analyses. Then, PPL was immobilized onto the nanofibers through adsorption and cross-linking methods. The optimum temperature for free PPL was determined to be 30 °C, and the optimum temperature for PPL immobilized on rPET/CA was determined to be 40 °C. It was observed that, especially under acidic conditions, after the immobilization process, PPL immobilized rPET/CA nanofibers became more resistant to pH changes than free PLL. Furthermore, the immobilized PPL exhibited improved pH stability, reusability, and thermal stability compared to its free counterpart. This innovative approach not only contributes to plastic waste reduction but also opens new avenues for enzyme immobilization with potential applications in biocatalysis and wastewater treatment.

Enhancing biocatalyst performance through immobilization of lipase (Eversa® Transform 2.0) on hybrid amine-epoxy core-shell magnetic nanoparticles

Magnetic nanoparticles were functionalized with polyethylenimine (PEI) and activated with epoxy. This support was used to immobilize Lipase (Eversa® Transform 2.0) (EVS), optimization using the Taguchi method. XRF, SEM, TEM, XRD, FTIR, TGA, and VSM performed the characterizations. The optimal conditions were immobilization yield (I.Y.) of 95.04 ± 0.79 %, time of 15 h, ionic load of 95 mM, protein load of 5 mg/g, and temperature of 25 °C. The maximum loading capacity was 25 mg/g, and its stability in 60 days of storage showed a negligible loss of only 9.53 % of its activity. The biocatalyst demonstrated better stability at varying temperatures than free EVS, maintaining 28 % of its activity at 70 °C. It was feasible to esterify free fatty acids (FFA) from babassu oil with the best reaction of 97.91 % and ten cycles having an efficiency above 50 %. The esterification of produced biolubricant was confirmed by NMR, and it displayed kinematic viscosity and density of 6.052 mm2/s and 0.832 g/cm3, respectively, at 40 °C. The in-silico study showed a binding affinity of -5.8 kcal/mol between EVS and oleic acid, suggesting a stable substrate-lipase combination suitable for esterification.

Metal-organic frameworks for enzyme immobilization and nanozymes: A laccase-focused review

Laccases are natural catalysts with remarkable catalytic activity. However, their application is limited by their lack of stability. Metal-organic frameworks (MOFs) have emerged as a promising alternative for enzyme immobilization. Enzymes can be immobilized in MOFs via two approaches: postsynthetic immobilization and in situ immobilization. In postsynthetic immobilization, an enzyme is embedded after MOF formation by covalent interactions or adsorption. In contrast, in in situ immobilization, a MOF is formed in the presence of an enzyme. Additionally, MOFs have exhibited intrinsic enzyme-like activity. These materials, known as nanozymes when they have the ability to replace enzymes in certain catalytic processes, have multiple key advantages, such as low cost, easy preparation, and large surface areas. This review presents a general overview of the most recent advances in both enzyme@MOF biocatalysts and MOF-based nanozymes in different applications, with a focus on laccase, which is one of the most widely investigated enzymes with excellent industrial potential.

Hydroxypropyl-β-Cyclodextrin-Glycerol-Assisted Extraction of Phenolics from Satureja montana L.: Optimization, Anti-Elastase and Anti-Hyaluronidase Properties of the Extracts

A green method for hydroxypropyl-β-cyclodextrin-glycerol-assisted extraction (HCGAE) of bioactive phenolics from S. montana, Lamiaceae was optimized using Box-Behnken design and response surface methodology and compared conventional water/ethanol-based extraction. The procedure was aimed at obtaining extracts with the maximum content of total phenols (TP), flavonoids (TF), dihydroxycinnamic acids (TDCA), rosmarinic acid (RA), and luteolin 7-O-glucoside (LG). The impact of glycerol content (0–70%), 2-hydroxypropyl-β-cyclodextrin content (0–0.4 mmol), temperature (20–70 °C), herbal material weight (0.3–0.8 g), extraction duration (5–25 min), and ultrasound power (144–720 W) on the extraction efficiency was analyzed. Four extracts with maximum amounts of target phenols, OPT-TP (5.93 mg/mL), OPT-TDCA-RA (4.17 mg/mL and 1.16 mg/mL, respectively), OPT-TF (0.99 mg/mL), and OPT-LG (0.28 mg/mL) were prepared. Comparison of the content of TDCA, TF, RA, and LG with those obtained in water/ethanol-based extraction demonstrated the superiority of the HCGAE approach for the extraction of phenols from S. montana. The extracts displayed good anti-elastase and excellent anti-hyaluronidase activity. IC50 values of the anti-hyaluronidase activity (1.67 ± 0.06 μL extract/mL, 1.16 ± 0.08 μL extract/mL, 0.85 ± 0.03 μL extract/mL, and 0.79 ± 0.05 μL extract/mL for OPT-TP, OPT-TDCA-RA, OPT-TF, and OPT-LG, respectively) surpassed that of the applied positive control, tannic acid. The observed bioactivity of the optimized extracts makes them promising active ingredients for natural cosmetics. The results of this research indicate that HCGAE is an excellent alternative to conventional water/ethanol-based extraction of phenolics from Satureja montana L.-yielding extracts with potent anti-elastase and anti-hyaluronidase properties suitable for direct use in cosmetic products.

Optimization of Cyclodextrin-Assisted Extraction of Phenolics from Helichrysum italicum for Preparation of Extracts with Anti-Elastase and Anti-Collagenase Properties

Helichrysum italicum is a plant traditionally used for skin-related disorders that is becoming an increasingly popular ingredient in cosmetic products. In this work, a "green" ultrasound-assisted extraction method for H. italicum phenolics was developed using skin-friendly cyclodextrins (CDs). Extraction conditions needed for the greatest yield of target compounds (total phenolics, phenolic acids, and flavonoids) were calculated. The composition of the extracts was determined using LC-MS and spectrophotometric methods. Among the tested CDs, 2-hydroxylpropyl-beta-CD (HP-β-CD) was the best suited for extraction of target phenolics and used to prepare two optimized extracts, OPT 1 (the extract with the highest phenolic acid content) and OPT 2 (the extract with the highest total phenol and flavonoid content). The extracts were prepared at 80 °C, using 0.089 g of plant material/g solvent (0.6 mmol of HP-β-CD), with or without addition of 1.95% (w/w) lactic acid. The main metabolite in both extracts was 3,5-O-dicaffeoylquinic acid. It was found that the addition of lactic acid greatly contributes to the extraction of arzanol, a well-known anti-inflammatory agent. IC₅₀ values of the anti-elastase (22.360 ± 0.125 μL extract/mL and 20.067 ± 0.975 for OPT-1 and OPT-2, respectively) and anti-collagenase (12.035 ± 1.029 μL extract/mL and 14.392 ± 0.705 μL extract/mL for OPT-1 and OPT-2, respectively) activities of the extracts surpassed those of the applied positive controls, namely ursolic and gallic acids. This activity deems the prepared extracts promising ingredients for natural cosmetics, appropriate for direct use in cosmetic products, removing the need for the evaporation of conventional solvents.

Photocatalytic degradation of dyes by novel electrospun nanofibers: A review

Textile industry is a significant contributor of wastewater, which contains pollutants including dye and other chemical substances. The release of thousands of tons of dye used in textile processing and finishing into natural streams and aquatic bodies present dire harm to the environment. In response to environmental concerns, a number of research have been done using low-cost technology to produce absorbents that can remove dyes from water bodies. Distinct techniques such as adsorption, enzymatic and photocatalytic degradation, etc. have been employed to remove dyes. In the last few decades, photocatalysis, a simple and green strategy, has emerged as the most valuable and recent principle that deals with wastewater treatment, using uniquely fabricated nanomaterials. Among them, rapid and versatile electrospinning methods have been used for the construction of a large surface area, hierarchical and reusable nanofibers for environmental remediation. As a flexible and fast fabrication method, reviewing the use of electrospun photocatalytic nanofibers, influential parameters in electrospinning and their effectiveness in the generation of oxidizing agents are a promising platform for the fabrication of novel nanomaterials in photocatalytic degradation of dyes. This review discusses techniques for dye removal, electrospun nanofibers, their fabrication and application in photocatalysis; mechanism of photocatalytic degradation, and challenges and suggested remedies for electrospun nanofibers in photocatalysis.

Bioremediation of petroleum hydrocarbon contaminated soil by microorganisms immobilized on sludge modified by non-ionic surfactant

The immobilization of microorganisms on high-quality and inexpensive carriers to remediate oil-contaminated soil is an effective strategy for contaminated soil remediation. Due to the abundance in nutrients, large specific surface area, and fewer pathogens, the composting sludge is considered a high-quality immobilized material. Herein, two non-ionic surfactants, TW-80 and sophorolipid, were used to modify composted sludge. High-efficiency petroleum hydrocarbon-degrading bacteria groups selected in the laboratory were fixed on the modified composting sludge under optimal conditions. The immobilized material was placed in the soil contaminated by petroleum hydrocarbons at an additive amount of 2wt/%, and a simulated remediation experiment was performed for 90 days. Both soil properties and microbial structure were characterized. Surfactant-modified compost sludge enhances the adsorption capacity to petroleum hydrocarbon. The immobilized microorganisms in the modified compost sludge showed a good effect on the remediation of soil contaminated by petroleum hydrocarbons. In addition, immobilized materials also increase the diversity of the microbial community structure in the soil. High-efficiency petroleum hydrocarbon-degrading bacteria immobilized on surfactant-modified compost can effectively promote the degradation of petroleum hydrocarbons in the soil and increase the abundance of microorganisms in the soil. It shows the feasibility of eco-friendly remediation of hydrocarbon-contaminated soil.

Recent advances in the utilization of immobilized laccase for the degradation of phenolic compounds in aqueous solutions: A review

Phenolic compounds such as phenol, bisphenol A, 2,4-dichlorophenol, 2,4-dinitrophenol, 4-chlorophenol and 4-nitrophenol are well known to be highly detrimental to both human and living beings. Thus, it is of critical importance that suitable remediation technologies are developed to effectively remove phenolic compounds from aqueous solutions. Biodegradation utilizing enzymatic technologies is a promising biotechnological solution to sustainably address the pollution in the aquatic environment as caused by phenolic compounds under a defined environmentally optimized strategy and thus should be investigated in great detail. This review aims to present the latest developments in the employment of immobilized laccase for the degradation of phenolic compounds in water. The review first succinctly delineates the fundamentals of biological enzyme degradation along with a critical discussion on the myriad types of laccase immobilization techniques, which include physical adsorption, ionic adsorption, covalent binding, entrapment, and self-immobilization. Then, this review presents the major properties of immobilized laccase, namely pH stability, thermal stability, reusability, and storage stability, as well as the degradation efficiencies and associated kinetic parameters. In addition, the optimization of the immobilized enzyme, specifically on laccase immobilization methods and multi-enzyme system are critically discussed. Finally, pertinent future perspectives are elucidated in order to significantly advance the developments of this research field to a higher level.

Environmental toxicity and decomposition of polyethylene

In the more than 100 years since the invention of plastics, various plastic polymers have been developed that exhibit different characteristics and have been widely used in production and life. In 2020 alone, nearly 400 million tons of plastics were produced globally. However, while plastic such as polyethylene brings us convenience, it also threatens environmental sustainability and human health. Due to insufficient recycling efficiency, millions of tons of polyethylene pollutants accumulate in terrestrial or marine environments each year. Polyethylene is elastic, chemically stable, and non-biodegradable, and the traditional disposal methods include landfilling and incineration. These methods are costly, unsustainable, and further increase the burden on the environment. Therefore, recent research has increasingly focused on the biodegradation of polyethylene. In this work, we briefly summarized polyethylene's properties and environmental toxicity. We also reviewed the recent advances in the biodegradation of polyethylene with a summary of traditional abiotic methods. Finally, we proposed a brief research direction in polyethylene study with the aspect of environmental toxicology and industrial applications of decomposition technology.

Hydroxyapatite/Glycyrrhizin/Lithium-Based Metal-Organic Framework (HA/GL/Li-MOF) Nanocomposite as Support for Immobilization of Thermomyces lanuginosus Lipase

The hydroxyapatite/glycyrrhizin/lithium-based metal-organic framework (HA/GL/Li-MOF) nanocomposites were synthesized via the hydrothermal method in the presence of lecithin and glycyrrhizin. Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS) were applied for characterization of the fabricated nanocomposites. The HA/GL/Li-MOF and Li-MOF nanocomposites were employed as support for immobilization of Thermomyces lanuginosus lipase (TLL). The Plackett-Burman and Box-Behnken designs were used for screening and optimizing of variables affecting the immobilization conditions, respectively. The optimum specific activity of immobilized TLL on HA/GL/Li-MOF and Li-MOF nanocomposites (41.8 ± 1.2 U/mg and 39.4 ± 3.1 U/mg, respectively) was predictably determined at support concentration of 0.5 mg/mL, glutaraldehyde concentration of 5 mM, and enzyme activity of 20 U/mg, while the specific activities of TLL@ HA/GL/Li-MOF and TLL@Li-MOF were experimentally found to be 39.5 ± 3.7 U/mg and 38.5 ± 2.3 U/mg, respectively. The stability results showed that the TLL@ HA/GL/Li-MOF has suitable stability against pH and thermal denaturation. However, the immobilized TLL on Li-MOF represented lower stability compared with that of the HA/GL/Li-MOF. The immobilized TLL on HA/GL/Li-MOF maintained near 70% of its original activity after 15 days' storage and during 5 runs of application. In addition, TLL@HA/GL/Li-MOF exhibited higher enzyme-substrate affinity (K_m, 10.1 mM) compared to that of TLL@Li-MOF (K_m, 23.4 mM). Therefore, these findings demonstrated the potential use of HA/GL/Li-MOF nanocomposites for enzyme immobilization.

Current Status and Future Perspectives of Supports and Protocols for Enzyme Immobilization

The market for industrial enzymes has witnessed constant growth, which is currently around 7% a year, projected to reach $10.5 billion in 2024. Lipases are hydrolase enzymes naturally responsible for triglyceride hydrolysis. They are the most expansively used industrial biocatalysts, with wide application in a broad range of industries. However, these biocatalytic processes are usually limited by the low stability of the enzyme, the half-life time, and the processes required to solve these problems are complex and lack application feasibility at the industrial scale. Emerging technologies create new materials for enzyme carriers and sophisticate the well-known immobilization principles to produce more robust, eco-friendlier, and cheaper biocatalysts. Therefore, this review discusses the trending studies and industrial applications of the materials and protocols for lipase immobilization, analyzing their advantages and disadvantages. Finally, it summarizes the current challenges and potential alternatives for lipases at the industrial level.

Optimization of immobilization of Pseudomonas cepacia lipase on multiwalled carbon nanotubes functionalized with glycyrrhizin and Tween 80

In the present study, multiwalled carbon nanotubes (MWCNTs) were functionalized with glycyrrhizin and Tween 80 and applied for immobilization of Pseudomonas cepacia lipase (PcL). Characterization of f-MWCNTs was performed through Fourier-transform infrared spectroscopy, thermal gravimetric, field emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy analysis. The optimum specific activity of immobilized PcL (studied by Plackett-Burman statistical design) occurred at 0.3 mg/mL of f-MWCNTs, 25 mM of phosphate buffer (pH 6.0), 15 min sonication time, 8 U/mL of enzyme concentration, and 24 h immobilization time at 4 °C in the absence of glutaraldehyde. In these conditions, the specific activity was 16.57 ± 0.71 U/mg, which was very close to the predicted amount (16.62 ± 0.64 U/mg). The results of thermal and pH stability showed that the stability of immobilized PcL was higher than that of the free PcL. The activity of immobilized PcL on f-MWCNTs held 93% after being incubated for 60 min at 70 °C. Moreover, the immobilized PcL on f-MWCNTs retained about 65% of its initial activity after 30 days of storage at 25 °C. In addition, about 50% of initial activity of immobilized PcL retained after 10 cycles of uses. Therefore, f-MWCNTs could be introduced as suitable support for enzymes immobilization.

Magnetic Metal Organic Framework Immobilized Laccase for Wastewater Decolorization

The laccase enzyme was successfully immobilized over a magnetic amino-functionalized metal–organic framework Fe3O4-NH2@MIL-101(Cr). Different techniques were used for the characterization of the synthesized materials. The Fe3O4-NH2@MIL-101(Cr) laccase showed excellent resistance to high temperatures and low pH levels with a high immobilization capacity and large activity recovery, due to the combination of covalent binding and adsorption advantages. The long-term storage of immobilized laccase for 28 days indicated a retention of 88% of its initial activity, due to the high stability of the immobilized system. Furthermore, a residual activity of 49% was observed at 85 °C. The immobilized laccase was effectively used for the biodegradation of Reactive Black 5 (RB) and Alizarin Red S (AR) dyes in water. The factors affecting the RB and AR degradation using the immobilized laccase (dye concentration, temperature and pH) were investigated to determine the optimum treatment conditions. The optimum conditions for dye removal were a 5 mg/L dye concentration, temperature of 25 °C, and a pH of 4. At the optimum conditions, the biodegradation and sorption-synergistic mechanism of the Fe3O4-NH2@MIL-101(Cr) laccase system caused the total removal of AR and 81% of the RB. Interestingly, the reusability study of this immobilized enzyme up to five cycles indicated the ability to reuse it several times for water treatment.

Electrospun nanofibers enhance trehalose synthesis by regulating gene expression for Micrococcus luteus fermentation

In this study, mesoporous polyacrylonitrile (PAN)/thermoplastic polyurethane (TPU) blended nanofibers were prepared to immobilize Micrococcus luteus for enhancing the conversion of trehalose. The images of SEM showed the cells were adsorbed on the surface and pores due to the unique pore structure. The results of contact angle, Zeta potential and water holding ratio exhibited the good hydrophilicity and stability of PAN/TPU-P2. Besides, it was indicated that the biomass and immobilization efficiency were increased to 0.633 g/L and 0.153 g/g, respectively. It was the most noteworthy that the trehalose yield could reach 23.46 g/L, which was 71.62 % higher than that of the control in the multi-batch fermentation. Moreover, the reactive oxygen species (ROS) level was decreased to 12.8 % while the enzyme concentration was increased to 11.176 mg/mL. Meanwhile, it was also found that PAN/TPU-P2 immobilization substantially increased the expression of target gene MtreY by 3.500 times. In other words, the mechanism by which immobilized cells increased trehalose yield was that PAN/TPU-P regulated gene expression of MtreY. Therefore, this research provided theoretical foundation for the metabolic regulation of sufficient trehalose production by immobilized cells.