Hollow silica microspheres as robust immobilization carriers

GDH-TiO2NFs-rGO photoelectrode: A novel photoelectric chemobiosensor for lipase activity detection

In the grain industry, lipases can hydrolyze the oils and fats in grains into glycerol and fatty acids, causing grain rancidity. If not detected and controlled, it would lead to the waste of grains and resources. In this research, rice bran was taken as the research object and a nanocomposite material with photoelectric activity, TiO2NFs-rGO, was developed by electrospinning technology. After immobilizing GDH enzyme, a photoelectrochemical biosensor, GDH-TiO2NFs-rGO-ITO, was constructed. When the glycerol content was within the range of 0.025-7 mmol/L, the photoelectric signal generated by the biosensor exhibited a favorable linear relationship with the glycerol content. The detection limit (S/N = 3) was 0.043 U/mL Even after seven uses, the detection of lipase activity still demonstrated high reproducibility. After being stored for 20 days, the photoelectric response value could still reach 81.37 % of that on the first day, indicating excellent storage stability. Moreover, other interfering substances in the test base solution did not generate obvious photoelectric responses, demonstrating high anti-interference ability. This biosensor indirectly, rapidly, and accurately detected lipase activity in rice bran. This study paves the way for the quality detection of rice bran during the storage period. In the future, it can be extended to the field of grain quality detection.

Biochemical properties of immobilized horseradish peroxidase on ceramic and its application in removal of azo dye

In the current work, electrostatic interactions were used to immobilize the horseradish peroxidase (HRP) onto five types of ceramic materials (C) with different concentrations of oxidized metals (C1-C5). The highest immobilization efficiency (70 and 77%) was detected at 6 mg C3 and 18 enzyme units. Scanning Electron Microscope (SEM), Energy Dispersive X-ray (EDX) and Fourier Transform Infrared (FTIR) analysis of C3-HRP confirmed the immobilization of the enzyme. After ten reuses, the reusability analysis showed that (66%) of the C3-HRP enzyme activity was retained. For C3-HRP, the optimum pH and temperature of the soluble enzyme were shifted from 7.0 and 30 °C to 6.0 and 50 °C. Up to 40 °C and 50 °C, respectively, the soluble HRP and C3-HRP remained steady. The kinetic analysis revealed that the Km and Vmax of soluble HRP and C3-HRP were, respectively, 5.5 mM, 0.66 units, and 8 mM, 0.52 units for hydrogen peroxide (H2O2) and 35.5 mM, 3.4 units and 40 mM, 1.1 units for guaiacol. Compared to soluble-HRP, the C3-HRP exhibited a greater oxidizing affinity toward several phenolic compounds (Guaiacol, o-dianisidine, o-phenylenediamine, pyrogallol, p-aminoantipyrine). In comparison with soluble-HRP, the C3-HRP showed increased stress tolerance with Triton X-100, urea, metals, isopropanol, and dimethyl sulfoxide. The C3-HRP removed methyl orange more effectively compared to soluble-HRP.

Effects of potential inducers to enhance laccase production and evaluating concomitant enzyme immobilisation

This work investigated non-polar solvent hexane and polar solvents methanol and ethanol as inducers besides a well-known inducer, copper, for laccase production with and without mesoporous silica-covered plastic packing under sterilised and unsterilised conditions. The potential of waste-hexane water, which is generated during the mesoporous silica production process, was also investigated as a laccase inducer. During the study, the free and immobilised laccase activity on the packing was measured. The results showed that the highest total laccase activity, approximately 10,000 Units, was obtained under sterilised conditions with 0.5 mM copper concentration. However, no immobilised laccase activity was detected except in the copper and ethanol sets under unsterilised conditions. The maximum immobilised laccase activity of the sets that used waste hexane as an inducer was 1.25 U/mg packing. According to its significant performance, waste hexane can be an alternative inducer under sterilised conditions. Concomitant immobilised packing showed satisfactory laccase activities and could be a promising method to reduce operation costs and improve the cost-efficiency of enzymatic processes in wastewater treatment plants.

Wall-Immobilized Biocatalyst vs. Packed Bed in Miniaturized Continuous Reactors: Performances and Scale-Up

Sustainable biocatalysis syntheses have gained considerable popularity over the years. However, further optimizations - notably to reduce costs - are required if the methods are to be successfully deployed in a range of areas. As part of this drive, various enzyme immobilization strategies have been studied, alongside process intensification from batch to continuous production. The flow bioreactor portfolio mainly ranges between packed bed reactors and wall-immobilized enzyme miniaturized reactors. Because of their simplicity, packed bed reactors are the most frequently encountered at lab-scale. However, at industrial scale, the growing pressure drop induced by the increase in equipment size hampers their implementation for some applications. Wall-immobilized miniaturized reactors require less pumping power, but a new problem arises due to their reduced enzyme-loading capacity. This review starts with a presentation of the current technology portfolio and a reminder of the metrics to be applied with flow bioreactors. Then, a benchmarking of the most recent relevant works is presented. The scale-up perspectives of the various options are presented in detail, highlighting key features of industrial requirements. One of the main objectives of this review is to clarify the strategies on which future study should center to maximize the performance of wall-immobilized enzyme reactors.

Polyhydroxyalkanoates, bacterially synthesized polymers, as a source of chemical compounds for the synthesis of advanced materials and bioactive molecules

Research into polyhydroxyalkanoates (PHAs) is growing exponentially. These bacterially derived polyesters offer a spectrum of possible applications, such as in manufacturing of daily-use objects, production of medical devices and implantable objects, or as synthons in chemical and pharmaceutical industries. Thanks to their broad physicochemical features, PHAs can be seen as polymers of the future, which can replace traditional petrochemical equivalents. As they are synthesized by bacteria through fermentation processes, these polyesters can be obtained from virtually any carbon source in a sustainable manner. Characterized by biodegradability and biocompatibility, they are used in many industries, ranging from production of everyday objects to medical applications. Furthermore, as they are built from bioactive monomers, namely (R)-3-hydroxyacids, they provide a platform for the synthesis of advanced chemical compounds. In this mini review, the reader will be acquainted with recent studies conducted at the Jerzy Haber Institute of Catalysis and Surface Chemistry of the Polish Academy of Sciences in collaboration with other groups that have contributed to the development of PHA-based medical materials, bioactive molecules and novel green solvents derived from PHA monomers.Key points• Polyhydroxyalkanoates are emerging polymers for biomedical applications• Polyhydroxyalkanoates can be modified easily to provide novel materials• (R)-3-Hydroxyacids are good synthons for bioactive substances and green solvents.