Covalently bonded pancreatic lipase onto the dithiocarbamate/chitosan-based magnetite: Stepwise fabrication of Fe 3 O 4 @CS/NHCS-Lip as a novel and promising nanobiocatalyst

A critical review of enzymes immobilized on chitosan composites: characterization and applications

Enzymes with industrial significance are typically used in biological processes. However, instability, high sensitivity, and impractical recovery are the major drawbacks of enzymes in practical applications. In recent years, the immobilization technology has attracted wide attention to overcoming these restrictions and improving the efficiency of enzyme applications. Chitosan (CS) is a unique functional substance with biocompatibility, biodegradability, non-toxicity, and antibacterial properties. Chitosan composites are anticipated to be widely used in the near future for a variety of purposes, including as supports for enzyme immobilization, because of their advantages. Therefor this review explores the effects of the chitosan's structure, molecular weight, degree of deacetylation on the enzyme immobilized, effect of key factors, and the enzymes immobilized on chitosan based composites for numerous applications, including the fields of biosensor, biomedical science, food industry, environmental protection, and industrial production. Moreover, this study carefully investigates the advantages and disadvantages of using these composites as well as their potential in the future.

Application of a novel composite of Fe3O4@SiO2/PAEDTC surrounded by MIL-101(Fe) for photocatalytic degradation of penicillin G under visible light

The novel photocatalyst of Fe3O4@SiO2/PAEDTC@MIL-101(Fe) was prepared based on the sol-gel method, and its structure and morphology were determined by SEM mapping, TEM, XRD, FTIR, and N2 adsorption-desorption analyses. The photocatalytic activity of nanocomposite was evaluated in comparison with other particles as well as adsorption and photolysis processes. The effect of operating parameters showed that the complete degradation of penicillin G (PNG) can be provided at a photocatalyst dosage of 0.6 g/L, radiation intensity of 36 W, pH of 5, and time of 60 min. In the optimum condition, 84% TOC removal was attained and the BOD5/COD rate for the treated effluent was above 0.4, which was representative of the high biodegradability of the treated effluent compared to the raw sample. The findings of energy consumption showed that PNG can be easily and effectively treated by the photocatalytic process based on magnetic MIL-101(Fe) with electrical energy per order between 10 and 20.87 kWh/m3. Due to the excellent interaction between the MIL-101(Fe) and Fe3O4@SiO2/PAEDTC, the photocatalyst stability test showed a recyclability of the particles for 5 consecutive reaction cycles with a minimum reduction of 7%. Solution treated with photocatalyst under UV and visible light sources explained that the toxicity of the effluent after treatment is significantly reduced with the growth of Escherichia coli. Scavenging experiments showed that •OH radical and hole (h+) are the main agents in degrading PNG to CO2, H2O, and biodegradable and low-toxicity products. Finally, the findings of the diagnostic analysis and comparative experiments proved that with the interaction of Fe3O4@SiO2, NH2, and MIL-101(Fe), a lower band gap can be prepared for more absorption of photons and pollutant and also more and faster production of active radicals.

A comparative study on Fe(III)-chitosan and Fe(III)-chitosan-CTAB composites for As(V) removal from water: preparation, characterization and reaction mechanism

Fe(III)-chitosan and Fe(III)-chitosan-CTAB composites were prepared using an ionotropic gelation method. Various techniques were used to analyze the morphology, structure, and property of the adsorbents, including SEM, EDS, FT-IR, XPS, and zeta potential. Compared with Fe(III)-chitosan, Fe(III)-chitosan-CTAB was more effective for As(V) adsorption at a wide range of pH (3.0-8.0). The adsorption of As(V) onto Fe(III)-chitosan and Fe(III)-chitosan-CTAB could reach equilibrium in 20 min, and their maximum adsorption capacities were 33.85 and 31.69 mg g^‒1, respectively. The adsorption kinetics was best described by the pseudo-second-order model (R² = 0.998 and 0.992), whereas the adsorption isotherm was fitted well by the Freundlich model (R² = 0.963 and 0.987). The presence of H₂PO₄^- significantly inhibited the adsorption of As(V) onto Fe(III)-chitosan and Fe(III)-chitosan-CTAB, and humic acid also led to a slight decrease in As(V) adsorption by Fe(III)-chitosan-CTAB. Over 94% of As(V) at the initial concentration of no more than 5 mg L^-1 was removed from real water by the two adsorbents. 1% (w/v) NaOH solution was determined to be the most suitable desorption agent. Fe(III)-chitosan and Fe(III)-chitosan-CTAB still maintained their initial adsorption capacities after five adsorption-desorption cycles. Based on different characterization results, both electrostatic attraction and surface complexation mechanisms played important roles in As(V) adsorption on Fe(III)-chitosan and Fe(III)-chitosan-CTAB.

Nanomaterial-based electrochemical enzymatic biosensors for recognizing phenolic compounds in aqueous effluents

With the rapid development of industrial society, phenolic pollutants already identified in water are severe threats to human health. Traditional detection techniques like chromatography are poor in the ability of cost-effectiveness and on-site detection. In recent years, electrochemical enzymatic biosensors have attracted increasing attention for use in the recognition of phenolic compounds, which is considered an effective strategy for the product transfer of portable analytical devices. Although electrochemical enzymatic biosensors provide a fast, accurate on-site detection technique, the difficulties of enzyme deactivation, poor stability and low sensitivity remain to be solved. Thus, effective immobilization methods of enzymes and nanomaterials with excellent properties have been extensively researched to obtain a high-sensitivity and high-stability biosensing platform. Simultaneous detection of multiple phenols may become the focus of further research. In this review, we provide an overview of recent progress toward electrochemical enzymatic biosensors for the detection of phenolic compounds, including enzyme immobilization approaches and advanced nanomaterials, especially nanocomposites with attractive properties such as good conductivity, high specific surface area, and porous structure. We will comprehensively discuss the features and mechanisms of the main enzymes adopted in the construction of different phenolic biosensors, as well as traditional methods (e.g., adsorption, covalent bonding, entrapment, encapsulation, cross-linking) of enzyme immobilization. The most effective method is based on the properties of enzymes, supports and application objective because there is no one-size-fits-all method of enzymatic immobilization. The emphasis will be given to various advanced nanomaterials, including their special nanostructures, preparation methods and performance. Finally, the main challenges in future research on electrochemical phenolic biosensors will be discussed to provide further perspectives for practical applications in dynamic and on-site monitoring. We believe this review will deliver an important inspiration for the construction of novel and high-performance electrochemical biosensors from enzyme selection to nanomaterial design for the detection of various hazardous materials. We believe this review will deliver an important inspiration on the construction of novel and high-performance electrochemical biosensors from the enzyme selection to the nanomaterial design for detections of various hazardous materials.

Novel magnetic lignosulfonate-supported Pd complex as an efficient nanocatalyst for N-arylation of 4-methylbenzenesulfonamide

This study presents a novel, economical, and environmentally technique for synthesizing magnetic palladium complex conjugated to activated calcium lignosulfonate with triethylenetetramine (Fe₃O₄@lignosulfonate@triethylenetetramine@Pd complex (FLT-Pd complex)) as a practical and air-stable catalyst. FLT-Pd complex is used as a catalyst for the fabrication of 4-methyl-N-phenyl-benzenesulfonamide derivatives via N-arylation of 4-methylbenzenesulfonamide in good yields. Furthermore, because of the complex magnetic reparability and high stability, it could be removed easily from the reaction media using a magnet and reused 5 cycles without a remarkable loss of catalytic prowess.

Different strategies for the lipase immobilization on the chitosan based supports and their applications

Immobilized enzymes have received incredible interests in industry, pharmaceuticals, chemistry and biochemistry sectors due to their various advantages such as ease of separation, multiple reusability, non-toxicity, biocompatibility, high activity and resistant to environmental changes. This review in between various immobilized enzymes focuses on lipase as one of the most practical enzyme and chitosan as a preferred biosupport for lipase immobilization and provides a broad range of studies of recent decade. We highlight several aspects of lipase immobilization on the surface of chitosan support containing various types of lipase and immobilization techniques from physical adsorption to covalent bonding and cross-linking with their benefits and drawbacks. The recent advances and future perspectives that can improve the present problems with lipase and chitosan such as high-price of lipase and low mechanical resistance of chitosan are also discussed. According to the literature, optimization of immobilization methods, combination of these methods with other techniques, physical and chemical modifications of chitosan, co-immobilization and protein engineering can be useful as a solution to overcome the mentioned limitations.

Protein morphology drives the structure and catalytic activity of bio-inorganic hybrids

Bio-hybrid materials have received a lot of attention in view of their bio-mimicking nature. One such biomimetic material with catalytic activity are the protein derived floral nanohybrid. Copper phosphate coordinated flakes can be curated to distinct floral morphology using proteins. Structurally two different proteins with similar size and with no known enzymatic activity are used to evaluate the role of protein structure and morphology, on the structure-activity relationship of the developed hybrid nanoflowers. Globular protein BSA and bacterial microcompartment domain protein PduBB' are selected. PduBB' because of self-assembling nature forms extended sheets, whereas BSA lacks specific assembly. The developed hybrid NFs differ in their morphology and also in their mimicry as a biological catalyst. The present investigation highlights the importance of the quaternary structure of proteins in tailoring the structure and function of the h-NFs. The results in this manuscript will motivate and guide designing, engineering and selection of glue material for fabricating biomacromolecule derived biohybrid material to mimic natural enzymes of potential industrial application.

Preparation of Chitosan/Magnetic Porous Biochar as Support for Cellulase Immobilization by Using Glutaraldehyde

In this work, porous biochar was obtained from sugarcane bagasse by alkali activation and pyrolysis and then magnetized with γ-Fe₂O₃ by calcination. After functionalization with chitosan and activation with glutaraldehyde, the as-prepared chitosan/magnetic porous biochar served as a support to immobilize cellulase by covalent bonds. The immobilization amount of cellulase was 80.5 mg cellulase/g support at pH 5 and 25 °C for 12 h of immobilization. To determine the enzymatic properties, 1% carboxymethyl cellulose sodium (CMC) (dissolved in 0.1 M buffer) was considered as a substrate for hydrolysis at different pH values (3–7) and temperatures (30–70 °C) for 30 min. The results showed that the optimum pH and temperature of the free and immobilized cellulase did not change, which were pH 4 and 60 °C, respectively. The immobilized cellulase had a relatively high activity recovery of 73.0%. However, it also exhibited a higher Michaelis–Menten constant (K_m) value and a slower maximum reaction velocity (V_max) value compared to the free enzyme. In the reusability assay, the immobilized cellulase showed initial glucose productivity of 330.9 mg glucose/g CMC and remained at 86.0% after 10 uses. In conclusion, the chitosan/magnetic porous biochar has great potential applications as a support for enzyme immobilization.

Production and use of immobilized lipases in/on nanomaterials: A review from the waste to biodiesel production

As a highly efficient and environmentally friendly biocatalyst, immobilized lipase has received incredible interest among the biotechnology community for the production of biodiesel. Nanomaterials possess high enzyme loading, low mass transfer limitation, and good dispersibility, making them suitable biocatalytic supports for biodiesel production. In addition to traditional nanomaterials such as nano‑silicon, magnetic nanoparticles and nano metal particles, novel nanostructured forms such as nanoflowers, carbon nanotubes, nanofibers and metal-organic frameworks (MOFs) have also been studied for biodiesel production in the recent years. However, some problems still exist that need to be overcome in achieving large-scale biodiesel production using immobilized lipase on/in nanomaterials. This article mainly presents an overview of the current and state-of-the-art research on biodiesel production by immobilized lipases in/on nanomaterials. Various immobilization strategies of lipase on various advanced nanomaterial supports and its applications in biodiesel production are highlighted. Influential factors such as source of lipase, immobilization methods, feedstocks, and production process are also critically discussed. Finally, the current challenges and future directions in developing immobilized lipase-based biocatalytic systems for high-level production of biodiesel from waste resources are also recommended.

TiO2 Sol-Gel Coated PAN/O-MMT Multi-Functional Composite Nanofibrous Membrane Used as the Support for Laccase Immobilization: Synergistic Effect between the Membrane Support and Enzyme for Dye Degradation

Removal of a triphenylmethane dye (crystal violet, CV) by a simultaneous enzymatic-photocatalytic-adsorption treatment was investigated in this work. A desirable synergistic effect on dye treatment was achieved by decorating laccase (Lac) onto the surface of TiO₂ sol-gel coated polyacrylonitrile/organically modified montmorillonite (PAN/O-MMT) nanofibers prepared by electrospinning. The assembly of Lac on the surface of PAN/O-MMT/TiO₂ nanofibers was confirmed by confocal laser scanning microscope (CLSM). In comparison with free Lac, the immobilized Lac showed better pH, temperature and operational stabilities, reaching highest relative activity at an optimum pH of 3 and optimum temperature of 50 °C. Therefore, the immobilized Lac displayed a higher degradation efficiency of CV at an initial dye concentration of 100 mg/L, an optimum pH of 4.5 and temperature at 60 °C. Under UV illumination, the CV removal efficiency was further improved by ~20%. These results demonstrated that the Lac-immobilized PAN/O-MMT/TiO₂ composite nanofibers with a combined effect between the immobilized enzyme and the polymeric support have potential for industrial dye degradation.

Biochemical aspects of lipase immobilization at polysaccharides for biotechnology

The design of immobilized enzyme preparations is an important and relevant area of modern sciences and technologies. Immobilization of enzymes from animal sources (component I) on natural carriers (component II) increases the system stability by protecting the active site of the enzyme from deactivation; facilitates the separation and accelerates the recovery of the enzyme. This makes reuse possible and provides a significant reduction in operating costs. Hydrolytic enzymes (such as lipases) and polysaccharides (such as chitosan) are the most promising of such pairs of components. The main attention here is devoted to the discussion on lipase immobilization on polysaccharide (mainly - chitin and chitosan). Based on the analysis of the available literature, the most adequate method is the immobilization of lipase from porcine pancreas (LPP) on polysaccharide particles (such as chitin or chitosan) pre-treated with ultrasound (to increase the particle surface area) and glutaraldehyde (for particle activation) that shows reasonably high LPP activity and stability. In order to increase further the activity of the lipase, some authors proposed to incorporate a spacer in the form of 1,3-diaminopropane (or 1,3-diaminobutane) prior to activation of the surface of the chitosan particles. In particular cases, the use of chitin (instead of chitosan) may be an alternative solution for biotechnological applications. Recently the idea of constructing "supramolecular enzyme systems" realized in the so-called "coimmobilized multienzymatic systems" strategy. The most fascinating example is the combined assay of a mixture of native LPP, glycerol kinase (from Cellulomonas) and glycerol-3-phosphate oxidase (from Aerococcus viridans) linked by glutaraldehyde to chitosan (as shell for inorganic nanoparticle core). This material was placed on a Pt-electrode as biosensor and was successfully applied for amperometric determination of the triglyceride level in the serum of healthy and diseased person. Thus, the whole innovative research-production sequence is described by Aggarwal V. and Pundir C.S.: from simple components to advanced material and further biomedical application. Thus, the following approach of lipase immobilization appears the most promising for future applications: a few types of lipases or the combination of LPP with some other enzymes immobilized simultaneously on multifunctional carriers (as nanohybrids of inorganic core and polysaccharide shell).

Synthesis and characterization of aminotetrazole-functionalized magnetic chitosan nanocomposite as a novel nanocarrier for targeted gene delivery

In the present study, Fe₃O₄/chitosan biopolymer grafted to a novel organosilane modified 5-amino-1H-tetrazole, a kind of drug intermediate, was successfully synthesized by chemical modification technique and evaluated as a high potential carrier of gene delivery. The loading capacity was evaluated, and in vitro release of nanocarrier was assessed using the dialysis method. The transfection efficiency of plasmid was optimal at an N/P ratio of 3. The chemically modified chitosan showed no inherent toxicity toward the cells. The synthesized nanocarrier had enhanced release of the plasmid at physiological pH 7.4. The N-functionalized magnetic chitosan nanocarrier demonstrated its efficacy in the enhancement of gene expression in the HECK-293T cell line. Therefore, the novel magnetic N-functionalized chitosan showed promise as a highly efficient gene carrier with potential applications in cancer therapy.

Post-synthetically modified SBA-15 with NH2-coordinately immobilized iron-oxine: SBA-15/NH2-FeQ3 as a Fenton-like hybrid catalyst for the selective oxidation of organic sulfides

We herein report the synthesis and catalysis of SBA-15 grafted iron-oxine. SBA-15/NH₂-FeQ₃ showed efficient catalytic activity in sulfide oxidation.

Application of Fe3O4@SiO2/(CH2)3-[imidazolium-SO3H]Cl as a robust, magnetically recoverable solid acid catalyst for the facile preparation of arylbispyranylmethanes

In this study, Fe3O4@SiO2/(CH2)3-[imidazolium-SO3H]Cl shows robust promoting capability in the synthesis of arylbispyranylmethane derivatives under mild and green conditions. Arylbispyranylmethanes were synthesized via efficient three-component reaction of various aromatic aldehydes with 4-hydroxy-6-methyl-2H-pyran-2-one. The nanomagnetic core-shell catalyst presented effective potential of at least eight times recycling applicability in the described synthetic procedure.