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•NaClO pretreatment improved wastewater environment for microalgae growth.•Pretreatment with 0.2 mg/L free chlorine increased microalgae growth inside beads.•Excessive NaClO ...pretreatment reduced microbial activity and pollutants removal.•Co-immobilized microalgae/bacteria system is effective in pollutants removal.•Integration of NaClO with microalgae improved food wastewater treatment efficiency.
Wastewater with 0.2, 0.4, 0.8, 1.0 mg/L free chlorine was biologically treated using co-immobilized microalgae/bacteria. In contrast, non-pretreated wastewater was treated with beads (control) and blank beads (blank) under the same operating condition. Results showed that NaClO pretreatment removed 8–33% total nitrogen (TN), 31–45% true color and 0.7–2.5 log CFU/mL aerobic-bacteria. At the end of treatment, maximum algal biomass (2,027 dry weight mg/L) was achieved with 0.2 mg/L free chlorine. Bacterial growth in wastewater was decreased by NaClO pretreatment before reaching 7.2–7.7 log CFU/mL on the fifth day. Beads with microorganisms (control) removed 15% more chemical-oxygen-demand (COD), 16% more TN, and 13% more total phosphate (PO43−) than blank. Pretreatment with 0.2 mg/L free chlorine increased TN removal from 75% to 80% while pollutants removal was substantially decreased with 0.4–1.0 mg/L free chlorine. Considering algal biomass growth and pollutants removal, 0.2 mg/L free chlorine pretreatment was recommended for microalgae/bacteria co-immobilized system.
Cascade catalysis that combines chemical catalysis and biocatalysis has received extensive attention in recent years, especially the integration of metal nanoparticles (MNPs) with enzymes. However, ...the compatibility between MNPs and enzymes, and the stability of the integrated nanocatalyst should be improved to promote the application. Therefore, in this study, we proposed a strategy to space-separately co-immobilize MNPs and enzymes to the pores and surface of a highly stable covalent organic framework (COF), respectively. Typically, Pd NPs that were prepared by in situ reduction with triazinyl as the nucleation site were distributed in COF (Tz-Da), and organophosphorus hydrolase (OPH) was immobilized on the surface of Tz-Da by a covalent method to improve its stability. The obtained integrated nanocatalyst Pd@Tz-Da@OPH showed high catalytic efficiency and reusability in the cascade degradation of organophosphate nerve agents. Furthermore, the versatility of the preparation strategy of COF-based integrated nanocatalyst has been preliminarily expanded: (1) Pd NPs and OPH were immobilized in the triazinyl COF (TTB-DHBD) with different pore sizes for cascade degradation of organophosphate nerve agent and the particle size of MNPs can be regulated. (2) Pt NPs and glucose oxidase were immobilized in COF (Tz-Da) to obtain an integrated nanocatalyst for efficient colorimetric detection of phenol.
In this study, co-immobilization of PLP and its dependent enzyme were investigated using a novel type of porous chitin bead (PCB). Crayfish shell was used to prepare PCB via dissolution of it to form ...beads, followed by the removal of CaCO3 and protein in-situ. Scanning electron microscopy, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller method showed that the PCB had abundant porous structures with deacetylation degree of 33 % and the specific surface area of 35.87 m2/g. Then, the beads are used to co-immobilize pyridoxal 5-phosphate (PLP) and l-lysine decarboxylase fused with chitin-binding protein (SpLDC-ChBD). Laser scanning confocal microscopy revealed that the beads could co-immobilize PLP and SpLDC-ChBD successfully. In addition, a packed bed was also constructed using the PCB containing co-immobilized SpLDC-ChBD and PLP. The substrate conversion remained at 91.09 % after 48 h with 50 g/L l-lysine, which showed good continuous catalysis ability. This study provides a novel method for co-immobilization of enzyme and PLP, as well as develops a new application of waste crustacean shells.
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•The waste crawfish shell was used to prepare porous chitin beads.•The beads were made porous by removing CaCO3 and proteins in situ.•The SpLDC-ChBD and PLP could be effectively co-immobilized on porous chitin beads.•A bioreactor was constructed using the prepared biocatalyst for the production of cadaverine.
Morus alba leaves are a natural product with great antidiabetic potential. However, the therapeutic efficacy of natural products is usually achieved through the interaction of active compounds with ...specific targets. Among them, active compounds with multi‐target therapeutic functions are more effective than single‐target enzymes. In this study, a bienzyme system was constructed by co‐immobilizing α‐amylase and α‐glucosidase onto Fe3O4 for affinity screening of dual‐target active components in the complex extract from M. alba leaves. As a result, a potential active compound was selectively screened by ligand fishing, separated by high‐speed countercurrent chromatography using a solvent system of ethyl acetate–n‐butanol–water (3:2:5, v/v), and identified as rutin. In addition, the result of molecular docking showed that rutin could interact with the active center of α‐amylase and α‐glucosidase through multiple hydrogen bonds, van der Waals forces, etc. to play an inhibitory role. These results demonstrate the effectiveness of the polydopamine magnetically immobilized bienzyme system for dual‐target affinity screening of active substances. This study not only reveals the chemical basis of the antidiabetic activity of M. alba leaves from a dual‐target perspective, but also promotes the progress of multitarget affinity screening.
The present study investigated the possibility of co-immobilization of caesium and strontium containing waste by metakaolin-based (MK) geopolymer. 4% of CsNO3 and 4% of Sr(NO3)2 by weight were used ...as simulants for radioactive Cs and Sr. The effect of Cs and Sr on the geopolymerization kinetics was determined via isothermal calorimetry. Furthermore, the evolution of mechanical properties, microstructure, and mineralogy was analysed. The results showed that Cs exerted no noticeable effect on reaction kinetics while Sr lowered the geopolymerization degree of MK geopolymer due to part of OH− from the activating solution being consumed by Sr2+, thereby reducing the activating capacity of pore solution. In addition, the pore structure analysis showed that the incorporation of Sr coarsened the microstructure of MK geopolymer while no significant change was observed with Cs. The phase analysis showed that no new phase was formed because of Cs or Sr incorporation. The mechanical properties decreased with Cs and Sr addition and a higher strength loss was observed for Sr-bearing geopolymers than that of Cs-bearing matrices. The strength reduction in Cs-bearing matrices is associated with the accompanying nitrate ions while a more pronounced strength reduction in Sr-bearing specimens is due to the synergistic effect of nitrates and Sr2+ on the geopolymerization. Despite that, the compressive strengths for all tested MK recipes met the minimum Belgian waste form acceptance criteria indicating that MK geopolymer preserved sufficient strength even at high Cs and Sr waste loadings. Thermodynamic modelling based on speciation and saturation index revealed that Cs+ was mainly bound through ion exchange, whereas Sr2+ largely precipitated as SrCO3. More importantly, it was observed that the co-immobilization of Cs and Sr by MK geopolymer is largely influenced by Sr behaviour. Based on the findings, it can be concluded that MK geopolymer is an excellent host material for Cs and Sr-based waste.
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► We have developed a reliable method to co-immobilize oligopeptides on implant surfaces. ► The coatings with co-immobilized peptides are mechanically stable and display the targeted ...bioactive properties. ► The co-immobilization of oligopeptides will deliver multifunctional surfaces for biomedical applications.
Functionalization of implants with multiple bioactivities is desired to obtain surfaces with improved biological and clinical performance. Our objective was developing a simple and reliable method to obtain stable multifunctional coatings incorporating different oligopeptides. We co-immobilized on titanium surface oligopeptides of known cooperative bioactivities with a simple and reliable method. Appropriately designed oligopeptides containing either RGD or PHSRN bioactive sequences were mixed and covalently bonded on CPTES-silanized surfaces. Coatings made of only one of the two investigated peptides and coatings with physisorbed oligopeptides were produced and tested as control groups. We performed thorough characterization of the obtained surfaces after each step of the coating preparation and after mechanically challenging the obtained coatings. Fluorescence labeling of RGD and PHSRN peptides with fluorescence probes of different colors enabled the direct visualization of the co-immobilization of the oligopeptides. We proved that the coatings were mechanically stable. The surfaces with co-immobilized RGD and PHSRN peptides significantly improved osteoblasts response in comparison with control surfaces, which assessed the effectiveness of our coating method to bio-activate the implant surfaces. This same simple method can be used to obtain other multi-functional surfaces by co-immobilizing oligopeptides with different targeted bioactivities – cell recruitment and differentiation, biomineral nucleation, antimicrobial activity – and thus, further improving the clinical performance of titanium implants.
Laccase, a green biocatalyst, has been widely used in the field of biodegradation with the assistance of electron mediators. Herein, a novel strategy, polyethyleneimine (PEI)-induced biomimetic ...mineralization, was explored and applied to co-immobilize laccase and 2,2′-azino bis (3-ethylbenzothiazoline)-6-sulfonic acid (ABTS). With the PEI doping, calcium phosphate (CaP) could facilely mineralize within 20 min to form PEI@CaP; ABTS could be co-mineralized with PEI to form (PEI + ABTS)@CaP. Laccase, a negatively charged protein, was then immobilized via electrostatic adsorption onto the embedded PEI in the carriers. Both of the immobilized laccase preparations, denoted as Lac-PEI@CaP and Lac-(PEI + ABTS)@CaP, showed high activity recoveries (96.4 % and 88.0 %, respectively), and increased pH tolerance and storage stability as compared to free laccase. ABTS and laccase loading densities of Lac-(PEI + ABTS)@CaP reached 0.83 mmol g−1 and 100 mg g−1, respectively. Lac-(PEI + ABTS)@CaP presented higher malachite green (MG) degradation capability than free laccase and Lac-PEI@CaP with free ABTS, possibly due to the proximity effect of the co-immobilized laccase and ABTS. Moreover, Lac-(PEI + ABTS)@CaP exhibited reusability and kept 83.2 % of MG degradation activity after three recycles and 37.9 % in the sixth. This work provided a new strategy for the co-immobilization of laccase and electron mediator, and demonstrated the potential of the biocatalyst for organic pollutant removal.
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•Fast mineralization of calcium phosphate (CaP) achieved with PEI or PEI plus ABTS.•Laccase was bound onto PEI@CaP and (PEI + ABTS)@CaP via electrostatic adsorption.•Lac-PEI@CaP and Lac-(PEI + ABTS)@CaP showed high activities and improved stabilities.•Lac-(PEI + ABTS)@CaP presented high performance and reusability in dye removal.
The present work emphasizes co-immobilization of enzymes (glucoamylase and α-amylase) on magnetic nanoparticles (MNPs) using glutaraldehyde as a cross-linking agent for the pre-treatment of Curcuma ...longa powder. The co-immobilization process was optimized under various processing parameters to retain the maximum activity of both the enzymes in their co-immobilized system. The maximum activity recovery for both enzymes was obtained at MNPs to enzyme ratio of 1:4 and 60 mM glutaraldehyde concentration in 120 min of cross-linking time. Synthesized MNPs were characterized before and after co-immobilization using various methods. The synthesized enzymes@AMNPs have appeared spherical in shape with a mean particle size of 100 nm. The prepared biocatalyst also possesses super magnetic property with saturation magnetization (Ms) of 36.1 emu/g. Further, the combined effect of prepared biocatalyst and low power ultrasound was used to pre-treat the turmeric root powder for curcuminoids extraction. The synergistic effect enhances the extraction yield by 1.3–1.5 fold under the optimized solvent extraction process compared to the individual approach. The curcuminoids were separated using crystallization, which resulted in 54% (w/w) isolation with 91% purity of curcuminoids. Finally, the prepared biocatalyst showed excellent reusability up to 10 cycles with almost 50% activity and retained more than 95% activity when stored for up to 30 days.
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•Glucoamylase and α-amylase were simultaneously co-immobilized on AMNPs.•Ultrasound & co-immobilized enzymes were used for pre-treatment of C. longa powder.•Various parameters were optimized to achieve maximum curcuminoids extraction.•Synthesized nano-biocatalyst (enzymes@AMNPs) exhibits high thermal and pH stability.•The enzymes@AMNPs showed excellent reusability and storage stability.
Lipases from Candida antarctica B (nonspecific lipase) and Rhizomucor miehei (1,3-specific lipase) were simultaneously immobilized on epoxy functionalized silica gel under mild conditions. The ...results showed rapid and simple immobilization of 4–15 mg of CALB:RML (different ratios 4:1, 2:1, 1.5:1, 1:1) on 1 g of support after 6 h. The thermal stability of derivatives and also their stability in methanol were greatly improved compared to the single immobilized enzyme. All the derivatives were also used to catalyze the transesterification of palm oil with methanol to produce fatty acid methyl esters (FAMEs). Response surface methodology (RSM) and a central composite rotatable design (CCRD) was used to study the effects of five factors, reaction temperature, methanol/oil ratio, reaction time, t-butanol concentration and CALB:RML ratio on the fatty acid methyl esters (FAME) yield. A quadratic polynomial equation was obtained for methanolysis reaction by multiple regression analysis. The optimum combinations for the reaction were CALB:RML ratio (2.5:1), t-butanol to oil (39.9 wt%), temperature (35.6 °C), methanol:oil ratio (5.9), reaction time 33.5 h. FAME yield of 78.3.5%, which was very close to the predicted value of 75.2%, was obtained. Verification experiment confirmed the validity of the predicted model.
•Lipases from Candida antarctica B and Rhizomucor miehei were simultaneously immobilized on silica.•The thermal stability of derivatives and also their stability in methanol were greatly improved.•All the derivatives were used to catalyze the transesterification of palm oil with methanol to produce biodiesel.•The increasing the amount of CALB relative to RML resulted to improving the thermal and methanol stability and FAME yield.
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