Preparation and characterization of a green nano-support for the covalent immobilization of glucoamylase from Neurospora sitophila

Nature-powered bio-cathodes: Synergistic effects of laccase immobilization and green nanoparticles on enhanced PGEs for sustainable biofuel cells

As part of growing energy demands and threats to ecology, there is an immense need for greener energy technologies that are novel, cost-effective, and ecofriendly. This paper presents a scalable strategy that uses biocompatible nanomaterials to modify the surface of a pencil graphite electrode (PGE) to enhance the performance of enzymatic biofuel cells (EBFC). Rosa centifolia flowers, an abundantly available plant extract, was used to green synthesize Ag and Cu nanoparticles and applied to various grades of pencil graphite lead surfaces (2H, HB, 2B) via dip-coating, and covalently immobilized with laccase enzyme. Unlike conventional nanoparticles, green-synthesized nanoparticles retain functional groups from phytochemicals that facilitate stable enzyme immobilization, resulting in effective electron transfer. Among the tested biocathodes 2B grade Lac/AgNP/PGE and Lac/CuNP/PGE demonstrated the highest open circuit potentials of 0.611 V and 0.498 V and current densities 1343.15 μA cm-2 and 1054.17 μA cm-2 respectively resulting in a significant raise of 70.84 % over pristine PGEs. Polarization studies revealed superior power density for Lac/AgNP/PGE-2B (20.629 μW cm-2 at 65.21 μA cm-2 current density) over Lac/CuNP/PGE-2B (17.39 μW cm-2 at 61.9 μA cm-2 current density). SEM confirmed enzyme immobilization, and FTIR and XPS validated the presence of carboxyl functional groups. Considering the stability of the modified electrode, Lac/AgNP/PGE-2B retained 62.93 % of its original current density on Day 20. This approach delivered a performance-enhanced biocathode design using functional nanomaterials and a bio-supportive strategy that displayed remarkable stability, longevity, and efficiency, and could potentially optimize the cost of EBFC design and promote miniaturization.

Enhancement of stability and activity of RSD amylase from Paenibacillus lactis OPSA3 for biotechnological applications by covalent immobilization on green silver nanoparticles

The key challenge to the biotechnological applications of amylases is achieving high activity and stability under extreme pH, temperature and often high levels of enzyme denaturants. This study immobilized a novel raw starch-digesting (RSD) amylase from Paenibacillus lactis OPSA3 on glutaraldehyde-activated silver nanoparticles. Effects of time, glutaraldehyde concentration, pH, temperature, and enzyme concentration on immobilization were studied, and the immobilized enzymes were characterized. pH 9.0 was optimum for the enzyme immobilization. The maximum immobilization efficiency of 82.23 ± 7.99 % was achieved at 25 °C for 120 min. After immobilization, the optimum pH and temperature changed from 9.0 to 11.0 and 60 to 70, respectively. Immobilization reduced the amylase's activation energy (KJ/mol) from the initial 58.862 to 45.449 following immobilization. The Km of the amylase decreased after immobilization, while the Vmax increased. The immobilized amylase showed significantly greater storage and thermal stability than the free amylase. At 80, enzyme half-life (min) and D value (min) increased from 12.33 to 179.11 and 40.94 to 594.98, respectively. The immobilized amylase (80-88 %) had more stability to the effects of the studied surfactants than the free enzyme. It also showed improved stability in the presence of commercial detergents compared to the free enzyme. The amylase's enhanced kinetic parameters and stability following successful immobilization on silver nanoparticles indicate its potential for application in the range of biotechnological processes where alkaline- and temperature-stable amylases are employed.

Green nanobiocatalysts: enhancing enzyme immobilization for industrial and biomedical applications

Nanobiocatalysts (NBCs), which merge enzymes with nanomaterials, provide a potent method for improving enzyme durability, efficiency, and recyclability. This review highlights the use of eco-friendly synthesis methods to create sustainable nanomaterials for enzyme transport. We investigate different methods of immobilization, such as adsorption, ionic and covalent bonding, entrapment, and cross-linking, examining their pros and cons. The decreased environmental impact of green-synthesized nanomaterials from plants, bacteria, and fungi is emphasized. The review exhibits the various uses of NBCs in food industry, biofuel production, and bioremediation, showing how they can enhance effectiveness and eco-friendliness. Furthermore, we explore the potential impact of NBCs in biomedicine. In general, green nanobiocatalysts are a notable progression in enzyme technology, leading to environmentally-friendly and effective biocatalytic methods that have important impacts on industrial and biomedical fields.

Novel biocatalysts based on enzymes in complexes with nano- and micromaterials

In today's world, there is a wide array of materials engineered at the nano- and microscale, with numerous applications attributed to these innovations. This review aims to provide a concise overview of how nano- and micromaterials are utilized for enzyme immobilization. Enzymes act as eco-friendly biocatalysts extensively used in various industries and medicine. However, their widespread adoption faces challenges due to factors such as enzyme instability under different conditions, resulting in reduced effectiveness, high costs, and limited reusability. To address these issues, researchers have explored immobilization techniques using nano- and microscale materials as a potential solution. Such techniques offer the promise of enhancing enzyme stability against varying temperatures, solvents, pH levels, pollutants, and impurities. Consequently, enzyme immobilization remains a subject of great interest within both the scientific community and the industrial sector. As of now, the primary goal of enzyme immobilization is not solely limited to enabling reusability and stability. It has been demonstrated as a powerful tool to enhance various enzyme properties and improve biocatalyst performance and characteristics. The integration of nano- and microscale materials into biomedical devices is seamless, given the similarity in size to most biological systems. Common materials employed in developing these nanotechnology products include synthetic polymers, carbon-based nanomaterials, magnetic micro- and nanoparticles, metal and metal oxide nanoparticles, metal-organic frameworks, nano-sized mesoporous hydrogen-bonded organic frameworks, protein-based nano-delivery systems, lipid-based nano- and micromaterials, and polysaccharide-based nanoparticles.

Trends in the development of innovative nanobiocatalysts and their application in biocatalytic transformations

The ever-growing demand for cost-effective and innocuous biocatalytic transformations has prompted the rational design and development of robust biocatalytic tools. Enzyme immobilization technology lies in the formation of cooperative interactions between the tailored surface of the support and the enzyme of choice, which result in the fabrication of tremendous biocatalytic tools with desirable properties, complying with the current demands even on an industrial level. Different nanoscale materials (organic, inorganic, and green) have attracted great attention as immobilization matrices for single or multi-enzymatic systems. Aiming to unveil the potentialities of nanobiocatalytic systems, we present distinct immobilization strategies and give a thorough insight into the effect of nanosupports specific properties on the biocatalysts' structure and catalytic performance. We also highlight the development of nanobiocatalysts for their incorporation in cascade enzymatic processes and various types of batch and continuous-flow reactor systems. Remarkable emphasis is given on the application of such nanobiocatalytic tools in several biocatalytic transformations including bioremediation processes, biofuel production, and synthesis of bioactive compounds and fine chemicals for the food and pharmaceutical industry.

Immobilization of enzymes on nanoinorganic support materials: An update

Despite the widespread use in various industries, enzyme's instability and non-reusability limit their applications which can be overcome by immobilization. The nature of the enzyme's support material and method of immobilization affect activity, stability, and kinetics properties of enzymes. Here, we report a comparative study of the effects of inorganic support materials on immobilized enzymes. Accordingly, immobilization of enzymes on nanoinorganic support materials significantly improved thermal and pH stability. Furthermore, immobilizations of enzymes on the materials mainly increased K_m values while decreased the V_max values of enzymes. Immobilized enzymes on nanoinorganic support materials showed the increase in ΔG value, and decrease in both ΔH and ΔS values. In contrast to weak physical adsorption immobilization, covalently-bound and multipoint-attached immobilized enzymes do not release from the support surface to contaminate the product and thus the cost is decreased while the product quality is increased. Nevertheless, nanomaterials can enter the environment and increase health and environmental risks and should be used cautiously. Altogether, it can be predicated that hybrid support materials, directed immobilization methods, site-directed mutagenesis, recombinant fusion protein technology, green nanomaterials and trailor-made supports will be used increasingly to produce more efficient immobilized industrial enzymes in near future.

Characterization of biogenically synthesized silver nanoparticles for therapeutic applications and enzyme nanocomplex generation

The present study describes green synthesis of silver nanoparticles (AgNPs) and inulin hydrolyzing enzyme nanocomplexes (ENC) using Azadirachta indica (Ai) and Punica granatum (Pg) leaf extracts. Surface topology and physico-chemical characteristics of AgNPs were studied using surface plasmon resonance (SPR), FTIR, SEM, AFM and EDX analyses. Particle size analysis using dynamic light scattering and AFM studies revealed that Ai-AgNPs (76.4 nm) were spherical in shape having central bigger nano-regime with smaller surroundings while Pg-AgNPs (72.1 nm) and ENCs (Inulinase-Pg-AgNPs ~ 145 nm) were spherical particles having smooth surfaces. Pg-AgNPs exhibited significant photocatalysis of a thiazine dye, methylene blue. Both Ai- and Pg-AgNPs showed selective antibacterial action by inhibiting pathogenic Bacillus cereus, while the probiotic Lactobacillus strains remained unaffected. Ai-AgNPs showed potential anti-biofilm effect (30% viability) on B. cereus biofilms. Pg-AgNPs showed anti-cancer effect against human colon cancer cell lines (Caco-2) resulting in 40% cell death in 48 h. Enzymes (inulinase, L-asparaginase and glucose oxidase) were successfully immobilized onto nanoparticles together with the biogenic synthesis of AgNPs and recyclability of the Inulinase-Pg-AgNPs complex was demonstrated. The study elaborates characteristics of green synthesized nanoparticles and their potential applications as anti-cancer, antibacterial and antioxidant nano drugs that could be used in food and nutraceutical industries. Enzyme immobilization on AgNPs without any toxic cross-linker opens up newer possibilites in enzyme-nanocomplex research.

Co-immobilization of pectinase and glucoamylase onto sodium aliginate/graphene oxide composite beads and its application in the preparation of pumpkin-hawthorn juice

Co-immobilization of pectinase and glucoamylase onto sodium alginate/graphene oxide beads was achieved by N,N'-dicyclohexylcarbodiimide/N-hydroxysuccinimide as activating agent. The co-immobilized pectinase-glucoamylase (I-PG) prepared under optimal conditions (pH 4.0, 40°C and 35 min) possessed pectinase activity of 1,227.5 ± 36.5U/g and glucoamylase activity of 1,027.2 ± 29.2U/g, with activity recovery of 73.8% and 85.2%, respectively. Both pectinase and glucoamylase in I-PG possessed wider pH tolerance and superior thermal stability to those of their free counterparts. Reusability studies indicated that both enzymes in I-PG retained over 60% of initial activity after six times of reuse. Conditions for the hydrolysis of the pumpkin-hawthorn compound juice by I-PG were optimized using orthogonal experiments. After treatment with I-PG, light transmittance, soluble solids, and reducing sugar content in the resulting juice increased significantly, whereas soluble protein and pectin content decreased appreciably. Therefore, the use of I-PG provided an effective and feasible method for improving quality of the pumpkin-hawthorn juice. PRACTICAL APPLICATIONS: In order to overcome the drawbacks of using free pectinase and glucoamylase, an effective method for the co-immobilization of these two enzymes onto sodium alginate/graphene oxide beads was developed. The co-immobilized pectinase/glucoamylase developed in this study could be applied in the clarification of juice rich in pectin and starch.