Effects of Pore Size and Crosslinking Methods on the Immobilization of Myoglobin in SBA-15

Enhancing industrial biocatalyst performance and cost-efficiency through adsorption-based enzyme immobilization: A review

Various enzymes such as lipases, proteases and laccases have been extracted for use in various industrial applications. However, most natural enzymes possess characteristics that make them unsuitable for the harsh conditions often associated with industrial processes. To overcome these limitations, various methods and techniques have been developed to enhance the suitability of enzymes as industrial biocatalysts, making them a viable alternative to chemical catalysts. One of the most effective approaches is enzyme immobilization, which improves enzyme properties such as thermal stability, organic solvent stability, enhanced efficiency, catalytic performance, prolonged storage, operational stability, and reusability. These improved characteristics lower manufacturing costs and provide more effective catalysts, making them essential for industrial applications. Enzyme immobilization typically involves attaching the enzyme to a solid support, and the microenvironment including the pH of the binding solution and the nature of the support often influences the immobilization rate. Immobilization techniques also play a crucial role in the success of the process. The adsorption method is being widely used due to its simplicity and minimal impact on enzyme structure. Through hydrogen bonds, ionic interactions, Van der Waals forces, and hydrophobic interactions, this method preserves the enzyme's active site, making it the preferred choice in industrial settings.

DFT and comparative adsorption study of NiO, MnO, and Mn2NiO4 nanomaterials for the removal of amaranth dye from synthetic water

In the current study, NiO nanoparticles, MnO nanoparticles, and Mn2NiO4 nanocomposites (Ni-NPs, Mn-NPs and MN-NCs, respectively) were synthesized using a facile hydrothermal method, and their performance in the removal of amaranth (AM) dye from synthetic wastewater was compared. XRD, FTIR spectroscopy, SEM, BET analysis, and TGA were performed to characterize the produced catalysts. The effect of pertinent parameters, including pH, dosage of catalysts, temperature, and shaking speed on the uptake of AM was investigated through batch experiments. The MN-NCs showed ultrafast and high efficiency for AM removal compared to their counter parts Mn-NPs and Ni-NPs. Under ideal conditions, the highest adsorption efficiencies of AM onto Ni-NPs, Mn-NPs, and MN-NCs were calculated to be 80.50%, 93.85%, and 98.50%, respectively. The Langmuir isotherm fitted the experimental data of AM removal better as shown by the higher values of r 2, compared to the Freundlich isotherm, indicating monolayer type adsorption of AM. According to kinetic analyses, the adsorption of AM was best described by the pseudo-second-order kinetic model. Further, regeneration/recycling studies showed that MN-NCs retained 79% adsorption efficiency after four cycles. DFT experiments were also conducted to gain a deeper understanding of the process and behavior of AM adsorption. In conclusion, as Ni-NPs, Mn-NPs, and MN-NCs adsorb AM predominantly via electrostatic interaction, they can be applied for the removal of both cationic and anionic dyes by controlling the pH factor.

Adsorption of β-Lactoglobulin on Thiol-Functionalized Mesoporous Silica

SBA-15 mesoporous materials were synthesized with different pore sizes (5 and 10 nm) and thiol-functionalized groups and then characterized to describe their ability to differentially adsorb β-lactoglobulin (BLG), a globular protein with an ellipsoid shape measuring 6.9 nm in length and 3.6 nm in width. All adsorption experiments showed that the adsorption capacities of mesoporous materials for BLG were dependent on the duration of contact between the two materials (mesoporous material and BLG) and the initial BLG concentration. It was also shown that the pore sizes and thiol groups of SBA-15-based adsorbents are important factors for the BLG adsorption capacities. Among the tested adsorbents, thiol-functionalized SBA-15 with a 10 nm pore size (SBA-15-SH-10) showed the highest adsorption capacity (0.560 g·g-1) under optimal experimental conditions. Kinetics studies demonstrated that the adsorption occurs predominantly inside the pores, with interactions occurring on heterogeneous surfaces. In addition, the thermodynamic parameters indicate a spontaneous and exothermic behavior of the BLG adsorption process onto the thiol-functionalized SBA-15 mesoporous adsorbent. Finally, the characterization of the SBA-15-SH-10 adsorbent at 308 K showed the occurrence of an oxidation reaction of the thiol groups to sulfonate groups during the adsorption process as confirmed by Raman spectroscopy. The spectra recorded after adsorption of the protein showed that this adsorption did not affect the secondary structure of the protein.

Advancing Adsorption and Separation with Modified SBA-15: A Comprehensive Review and Future Perspectives

Mesoporous silica SBA-15 has emerged as a promising adsorbent and separation material due to its unique structural and physicochemical properties. To further enhance its performance, various surface modification strategies, including metal oxide and noble metal incorporation for improved catalytic activity and stability, organic functionalization with amino and thiol groups for enhanced adsorption capacity and selectivity, and inorganic-organic composite modification for synergistic effects, have been extensively explored. This review provides a comprehensive overview of the recent advances in the surface modification of SBA-15 for adsorption and separation applications. The synthesis methods, structural properties, and advantages of SBA-15 are discussed, followed by a detailed analysis of the different modification strategies and their structure-performance relationships. The adsorption and separation performance of functionalized SBA-15 materials in the removal of organic pollutants, heavy metal ions, gases, and biomolecules, as well as in chromatographic and solid-liquid separation, is critically evaluated. Despite the significant progress, challenges and opportunities for future research are identified, including the development of low-cost and sustainable synthesis routes, rational design of SBA-15-based materials with tailored properties, and integration into practical applications. This review aims to guide future research efforts in developing advanced SBA-15-based materials for sustainable environmental and industrial applications, with an emphasis on green and scalable modification strategies.

An antifouling epoxy coated metal surface containing silica-immobilized carbonic anhydrase supraparticles for CO2 capture through microalgae

Carbonic anhydrase (CA) has a promising application as a green and efficient biocatalyst for CO2 capture, and many successful cases of immobilizing CA have been reported. However, CA antifouling coatings on metal for CO2 sequestration have rarely been reported. Herein, dimeric CA from Sulfurihydrogenibium azorense (SazCA) with a ferritin tag, which was prepared by low-speed centrifugation with high yield, was adopted as a free enzyme and encapsulated in the sol-gel silica. The silica-immobilized CAs were dispersed into the commercialized metal-antifouling epoxy resin paint to obtain CA coated nickel foams, which had excellent stability, with 90 % and 67 % residual activity after 28 days of incubation at 30 °C and 60 °C, respectively. The CA coated nickel foams remained 60 % original activity after 6 cycles of use within 28 days. Then, a CA-microalgae carbon capture device was constructed using the CA coated nickel foams and Chlorella. The growth rate of Chlorella was significantly increased and the biomass of Chlorella increased by 29 % compared with control after 7 days of incubation. Due to the simple and cost-effective preparation process, sustainable and efficient CO2 absorption, this easy-to-scale up CA coated nickel foam has great potential in CA assisted microalgae-based CO2 capture and carbon neutrality.

Fabrication of a Floatable Micron-Sized Enzyme Device Using Diatom Frustules

Immobilization of enzymes has been widely reported due to their reusability, thermal stability, better storage abilities, and so on. However, there are still problems that immobilized enzymes do not have free movements to react to substrates during enzyme reactions and their enzyme activity becomes weak. Moreover, when only the porosity of support materials is focused, some problems such as enzyme distortion can negatively affect the enzyme activity. Being a solution to these problems, a new function "floatability" of enzyme devices has been discussed. A "floatable" micron-sized enzyme device was fabricated to enhance the free movements of immobilized enzymes. Diatom frustules, natural nanoporous biosilica, were used to attach papain enzyme molecules. The floatability of the frustules, evaluated by macroscopic and microscopic methods, was significantly better than that of four other SiO2 materials, such as diatomaceous earth (DE), which have been widely used to fabricate micron-sized enzyme devices. The frustules were fully suspended at 30 °C for 1 h without stirring, although they settled at room temperature. When enzyme assays were performed at room temperature, 37, and 60 °C with or without external stirring, the proposed frustule device showed the highest enzyme activity under all conditions among papain devices similarly prepared using other SiO2 materials. It was confirmed by the free papain experiments that the frustule device was active enough for enzyme reactions. Our data indicated that the high floatability of the reusable frustule device, and its large surface area, is effective in maximizing enzyme activity due to the high probability to react to substrates.

Synthesis and Design of a Synthetic-Living Material Composed of Chitosan, Calendula officinalis Hydroalcoholic Extract, and Yeast with Applications as a Biocatalyst

Design and development of materials that couple synthetic and living components allow taking advantage of the complexity of biological systems within a controlled environment. However, their design and fabrication represent a challenge for material scientists since it is necessary to synthesize synthetic materials with highly specialized biocompatible and physicochemical properties. The design of synthetic-living materials (vita materials) requires materials capable of hosting cell ingrowth and maintaining cell viability for extended periods. Vita materials offer various advantages, from simplifying product purification steps to controlling cell metabolic activity and improving the resistance of biological systems to external stress factors, translating into reducing bioprocess costs and diversifying their industrial applications. Here, chitosan sponges, functionalized with Calendula officinalis hydroalcoholic extract, were synthesized using the freeze-drying method; they showed small pore sizes (7.58 μm), high porosity (97.95%), high water absorption (1695%), and thermal stability, which allows the material to withstand sterilization conditions. The sponges allowed integration of 58.34% of viable Saccharomyces cerevisiae cells, and the cell viability was conserved 12 h post-process (57.14%) under storage conditions [refrigerating temperature (4 °C) and without a nutrient supply]. In addition, the synthesized vita materials conserved their biocatalytic activity after 7 days of the integration process, which was evaluated through glucose consumption and ethanol production. The results in this paper describe the synthesis of complex vita materials and demonstrate that biochemically modified chitosan sponges can be used as a platform material to host living and metabolically active yeast with diverse applications as biocatalysts.

Surface Functionalization of SBA-15 for Immobilization of Myoglobin

Mesoporous molecular sieve SBA-15 was successfully modified with 3-aminopropyltriethoxysilane (APTES) and 3-glycidyloxypropyltrimethoxysilane (GPTMS). The functionalized SBA-15 were characterized by small-angle X-ray (SAXRD), thermogravimetric analysis (TG), N₂ adsorption, and Fourier transformed infrared spectrum (FT-IR). APTES functionalized SBA-15 (named SBA-15-A) and GPTMS functionalized SBA-15 (named SBA-15-G) were used to immobilize myoglobin (Mb). The loading amounts of Mb by SBA-15-A and SBA-15-G were 511.2 and 547.8 mg/g, respectively, whereas only 359.6 mg/g was achieved by SBA-15. Mb/SBA-15-G and Mb/SBA-15-A demonstrated better reusability than SBA-15, retaining 84.6% and 82.7% of the initial activity after repeated use seven times. The Mb/SBA-15-A and Mb/SBA-15-G also exhibited improved thermal stability and storage stability.