Immobilized enzymes in inorganic hybrid nanoflowers for biocatalytic and biosensing applications

Enzymes encapsulated in organic-inorganic hybrid nanoflower with spatial localization for sensitive and colorimetric detection of formate

Formate is an important environmental pollutant, and meanwhile its concentration change is associated with a variety of diseases. Thus, rapid and sensitive detection of formate is critical for the biochemical analysis of complex samples and clinical diagnosis of multiple diseases. Herein, a colorimetric biosensor was constructed based on the cascade catalysis of formate oxidase (FOx) and horseradish peroxidase (HRP). These two enzymes were co-immobilized in Cu3(PO4)2-based hybrid nanoflower with spatial localization, in which FOx and HRP were located in the shell and core of nanoflower, respectively (FOx@HRP). In this system, FOx could catalyze the oxidation of formate to generate H2O2, which was then utilized by HRP to oxidize 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid to yield blue product. Ideal linear correlation could be obtained between the absorbance at 420 nm and formate concentration. Meanwhile, FOx@HRP exhibited excellent detection performance with low limit of detection (6 μM), wide linear detection range (10-900 μM), and favorable specificity, stability and reusability. Moreover, it could be applied in the detection of formate in environmental, food and biological samples with high accuracy. Collectively, FOx@HRP provides a useful strategy for the simple and sensitive detection of formate and is potentially to be used in biochemical analysis and clinical diagnosis.

Unraveling the orientation of an enzyme adsorbed onto a metal-organic framework

Bio-conversion of lignocellulosic biomass to bioethanol fuel is a highly desirable yet challenging objective because of the low catalytic activity and high cost of β-glucosidase (BGL). Recently, ZIF-8, an emerging organic porous material, has been proposed as a promising candidate for enzyme immobilization to improve associated activity and stability. However, the underlying interaction mechanism of binding BGL on the ZIF-8 surface is yet to be clarified. Here, the adsorption of BGL onto ZIF-8 is explored for the first time by molecular dynamics simulations. The results show that BGL adsorbs on the ZIF-8 surface with a "back-on" orientation. The adsorption free energy analysis shows that the adsorption process is enthalpy driven. In addition, the electrostatic interaction between negatively charged residues and Zn2+ on the surface of ZIF-8 is found to play a decisive role in surface binding, which accounts for 98% of the total interaction energy. The secondary structure of BGL is not affected despite the strong adsorption, suggesting the good biocompatibility of ZIF-8. This study not only provides a reliable theoretical insight into understanding the interaction mechanism between BGL and ZIF-8, but also helps the rational design of ZIF-8-based materials for bio-related applications.

A new method to immobilize urease in silk fibroin membrane by unidirectional nanopore dehydration

The immobilization of free enzymes is crucial for enhancing their stability in different environments, enabling reusability, and expanding their applications. However, the development of a straightforward immobilization method that offers stability, high efficiency, biocompatibility, and modifiability remains a significant challenge. Silk fibroin (SF) is a good carrier for immobilized enzymes and drugs. Here, we employed urease as a model enzyme and utilized our developed technology called unidirectional nanopore dehydration (UND) to efficiently dehydrate a regenerated SF solution containing urease in a single step, resulting in the preparation of a highly functionalized SF membrane immobilizing urease (UI-SFM). The preparation process of UI-SFM is based on an all-water system, which is mild, green and able to efficiently and stably immobilize urease in the membranes, maintaining 92.7% and 82.8% relative enzyme activity after 30 days of storage in dry and hydrated states, respectively. Additionally, we performed additional post-treatments, including stretching and cross-linking with polyethylene glycol diglycidyl ether (PEGDE), to obtain two more robust immobilized urease membranes (UI-SFMs and UI-SFMc). The thermal and storage stability of these two membranes were significantly improved, and the recovery ratio of enzyme activity reached more than 90%. After 10 repetitions of the enzymatic reaction, the activity recovery of UI-SFMs and UI-SFMc remained at 92% and 88%, respectively. The results suggest that both UND-based and post-treatment-developed membranes exhibit excellent urease immobilization capabilities. Furthermore, the enzyme immobilization method offers a straightforward and versatile approach for efficient and stable enzyme immobilization, while its flexible modifiability caters to diverse application requirements.

Application and Cytotoxicity Evaluation of Fe-MIL-101 Nanozyme in Milk

In this study, we used Fe-MIL-101 nanozyme to convert lactose into lactitol, and it was proved that Fe-MIL-101 nanozyme has lactase-like activity. Due to the potential health effects of nanomaterials, we evaluated the cytotoxicity of Fe-MIL-101 nanozyme. To reduce the potential toxicity of the nanozyme, we applied centrifugation and membrane filtration. When the membrane aperture size was 100 nm, the residual content of Fe-MIL-101 nanozyme was 14.09 μg/mL. The residual content of Fe-MIL-101 nanozyme was reduced by optimizing time, temperature, and Fe-MIL-101 nanozyme-to-substrate ratio. It was showed that the concentration of Fe was 38.47 mg/kg and the concentration of H2BDC was 0 mg/kg under optimized conditions (110℃, 2 h of reaction and the ratio of Fe-MIL-101 nanozyme to substrate is 1:20). The result met the national standard of China. Experiments measuring cytotoxicity, oxidative stress, and cell membrane damage revealed that less than 20 μg/mL Fe-MIL-101 nanozyme had no significant cytotoxicity. Our study findings showed that Fe-MIL-101 nanozyme reduced lactose content in milk.

Site-directed display of zearalenone lactonase on spilt-intein functionalized nanocarrier for green and efficient detoxification of zearalenone

In this study, we prepared a functional organic-inorganic hybrid nanoflower (InHNF) via split intein moiety in a biomineralization process without using organic solvents. InHNF could specifically bind the target enzymes from crude cell lysates within seconds and site-directedly display them on the surface by forming a peptide bond with enzyme's terminal amino acid residue. This unique feature enabled InHNF to increase the specific activity of zearalenone detoxifying enzyme ZHD518 by 40 ∼ 60% at all tested temperatures and prevented enzyme denaturation even under extreme pH conditions (pH 3-11). Furthermore, it exhibited excellent operational stability, with a residual activity of over 70% after eight reaction cycles. Strikingly, InHNF-ZHD518 achieved above 50% ZEN degradation despite the near inactivation of free ZHD518 in beer sample. Overall, InHNF nanocarriers can achieve environmentally friendly, purification-free, and site-directed immobilization of food enzymes and enhance their catalytic properties, making them suitable for a wide range of industrial applications.

A review on the immobilization of bromelain

This review shows the endeavors performed to prepare immobilized formulations of bromelain extract, usually from pineapple, and their use in diverse applications. This extract has a potent proteolytic component that is based on thiol proteases, which differ depending on the location on the fruit. Stem and fruit are the areas where higher activity is found. The edible origin of this enzyme is one of the features that determines the applications of the immobilized bromelain to a more significant degree. The enzyme has been immobilized on a wide diversity of supports via different strategies (covalent bonds, ion exchange), and also forming ex novo solids (nanoflowers, CLEAs, trapping in alginate beads, etc.). The use of preexisting nanoparticles as immobilization supports is relevant, as this facilitates one of the main applications of the immobilized enzyme, in therapeutic applications (as wound dressing and healing components, antibacterial or anticancer, mucus mobility control, etc.). A curiosity is the immobilization of this enzyme on spores of probiotic microorganisms via adsorption, in order to have a perfect in vivo compatibility. Other outstanding applications of the immobilized enzyme are in the stabilization of wine versus haze during storage, mainly when immobilized on chitosan. Curiously, the immobilized bromelain has been scarcely applied in the production of bioactive peptides.

Parazoanthus axinellae Extract Incorporated Hybrid Nanostructure and Its Potential Antimicrobial Activity

This study, it was aimed to examine the change in the antimicrobial effect of sea anemone Parazoanthus axinellae extract by forming its nanoflowers. A scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX) were expended to observe the morphologies of the Cu NFs that had been produced. Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) techniques were expended to analyze the managing assemblies in P. axinellae extract, which perform an effective part in the synthesis routine, as well as the crystal assembly of NFs. P. axinellae extract mediated the HNFs (Hybrid nanoflowers) are at high, pure crystalline nature, flower shape with a crystallographic system at the nanoscale with mean crystallite size 21.9 nm using XRD, and average particle size ~10 nm by SEM. The broad absorption band at 2981-2915 cm-1 in the FT-IR spectra of anemone extract and Cu-anemone NFs represents the unique peak of hydroxy groups. In addition, Cu NFs were tested for their antibacterial properties. Cu NFs have been discovered to exhibit antibacterial properties. It is suggested that P. axinellae extract and various inorganic components be used to synthesize a variety of NFs and assess their suitability for usage in biomedical fields.

Multipoint Immobilization at Inert Center of Papain on Homo-Functional Diazo-Activated Silica Support: A Way of Restoring "Above Room-Temperature" Bio-Catalytic Sustainability

Although enzymes play a significant role in industrial applications, their potential usage at high-level efficiency, particularly above room temperature, has not yet been fully harnessed. It brings above room-temperature catalytic sustainability of an immobilized (imm.) bio-catalyst as a long pending issue to improve enzyme stability, activity, specificity, or selectivity, particularly the enantio-selectivity over the native-enzymes. At this juncture, in a robust methodology, a heterogeneous solid phase bio-catalyst, {Si(OSi)₄(H₂O)_1.03}_n=328{OSi(CH₃)₂-NH-C₆H₄-N═N}₄{papain}(H₂O)₂₅₁, has efficiently been prepared by immobilizing papain on homo-functionalized SG (silica-gel) via multipoint covalent attachment. The bio-catalyst is easy to be recovered and reused multiple times. The homo-functional -N═N⁺, which appears on the SG-surface, makes the multipoint diazo-links with the inert center of the tyrosine-moiety to couple the enzyme where all the amino, thiol, phenol, and so forth, groups of the protein, including those that belong to the active-site, remain intact. The immobilized enzyme (13.9 μmol g^-1) swims in pore-water within the pore-channel, remains stable up to 70 ± 5 °C, and exhibits wider temperature adaptability in performing its hydrolyzing activities. The relative activity, 78 ± 2% at 27 °C, remains quantitative for 60 days and can be reused for 60 cycles with 53% activity at room-temperature. The thermal (relative activity: 87%; incubated at 70 ± 5 °C for 24 h) and mechanical (relative activity: 92%; incubated at 2500 rpm for 2 h at 27 °C) stability was outstanding.

In Situ Synthesis of Horseradish Peroxidase Nanoflower@Carbon Nanotube Hybrid Nanobiocatalysts with Greatly Enhanced Catalytic Activity

Organic-inorganic hybrid nanoflowers (NFs) consisting of horseradish peroxidase (HRP) and copper II (Cu²⁺) are successfully synthesized with the involvement of carbon nanotubes (CNTs) by in situ and post-modification methods. Catalytic activities of in situ synthesized HRP-NF@CNT (HRP-NF@CNT-Is) and post-modification-synthesized HRP-NF@CNTs (HRP-NF@CNT-Pm) are systematically examined. The 30 mg CNTs incorporated HRP-NF@CNT-Is (HRP-NF@CNT-30Is) exhibits greatly increased catalytic activity and stability toward 3,3',5,5'-tetramethylbenzidine (TMB), thanks to the synergistic effect between HRP-NF and CNTs and the peroxidase-like activity of CNTs in the presence of hydrogen peroxide (H₂O₂). While HRP-NF@CNT-30Is retains almost 85% of its initial activity even after 10 cycles, HRP-NF (without CNTs) loses half of its initial activity at the same experimental conditions. We study how two experimental parameters, the pH values and temperatures, influence the catalytic activity of HRP-NF@CNT-30Is, in addition to the fact that HRP-NF@CNT-30Is is employed to detect the presence of H₂O₂ and glutathione (GSH) with colorimetric and spectrophotometric readouts. For instance, HRP-NF@CNT-30Is is used to sensitively detect H₂O₂ in the range of 20 to 300 μM with an LOD of 2.26 μM. The catalytic activity of HRP-NF@CNT-30Is is suppressed in the presence of GSH, and then an obvious color change from blue to nearly colorless is observed. Using this strategy, GSH is also sensitively determined in the range of 20-200 μM with an LOD of 11.2 μM. We expect that HRP-NF@CNTs can be used as a promising and novel nanobiocatalyst for various biomedical and industrial applications in the near future.

One-Pot Synthesis of Enzyme and Antibody/CaHPO4 Nanoflowers for Magnetic Chemiluminescence Immunoassay of Salmonella enteritidis

In this study, through a bioinspired strategy, the horseradish peroxidase (HRP) and antibody (Ab) were co-embedded into CaHPO₄ to prepare HRP-Ab-CaHPO₄ (HAC) bifunctional hybrid nanoflowers by one-pot mild coprecipitation. The as-prepared HAC hybrid nanoflowers then were utilized as the signal tag in a magnetic chemiluminescence immunoassay for application in the detection of Salmonella enteritidis (S. enteritidis). The proposed method exhibited excellent detection performance in the linear range of 10-10⁵ CFU/mL, with the limit of detection (LOD) of 10 CFU/mL. This study indicates great potential in the sensitive detection of foodborne pathogenic bacteria in milk with this new magnetic chemiluminescence biosensing platform.

Antibiotic-enzyme-inorganic nanoflowers based immunoassay for the ultrasensitive detection of Staphylococcus aureus

In this work, we constructed a moderate and convenient approach for the determination of staphylococcus aureus (S. aureus) by using organic-inorganic flower-like hybrid nanoflowers and Pig IgG together in an enzyme-linked immunosorbent assay (ELISA) system. To ensure efficient capture, the hybrid nanoflowers were prepared by encapsulating horseradish peroxidase (HRP) and vancomycin (VAN) in the inorganic nanocrystal composites (calcium ion solution), just like the mimic biomineralization process. Owing to the self-assembly technique, the synthesized VAN-HRP-CaHPO₄ nanoflowers (NFs) can not only retain the ability to particularly capture the gram-positive bacteria but also enhance the stability and enzymatic activity to achieve the signal output amplification. Then, taking advantage of the integration of signal amplification elements (HRP) and biorecognition unit (VAN), the VAN-HRP-CaHPO₄ NFs were utilized as a new kind of capture & signal regent in the procedure of S. aureus detection. Based on this ELISA system, S. aureus could be clearly detected within the concentration ranging from 1.0 × 10² to 1.0 × 10⁷ CFU mL^-1. The detection limit was defined as 4.3 CFU mL^-1, which performance is superior to some commercial ELISA kits. Additionally, this system detected the S. aureus in food samples and showed an acceptable recovery. As a cost-effective and sensitive platform, this proposed assay was enable to fulfill the requirement of a quick and effective detection of S. aureus.

Bioelectrocatalysis for CO2 reduction: recent advances and challenges to develop a sustainable system for CO2 utilization

Activation and turning CO₂ into value added products is a promising orientation to address environmental issues caused by CO₂ emission. Currently, electrocatalysis has a potent well-established role for CO₂ reduction with fast electron transfer rate; but it is challenged by the poor selectivity and low faradic efficiency. On the other side, biocatalysis, including enzymes and microbes, has been also employed for CO₂ conversion to target C_n products with remarkably high selectivity; however, low solubility of CO₂ in the liquid reaction phase seriously affects the catalytic efficiency. Therefore, a new synergistic role in bioelectrocatalysis for CO₂ reduction is emerging thanks to its outstanding selectivity, high faradic efficiency, and desirable valuable C_n products under mild condition that are surveyed in this review. Herein, we comprehensively discuss the results already obtained for the integration craft of enzymatic-electrocatalysis and microbial-electrocatalysis technologies. In addition, the intrinsic nature of the combination is highly dependent on the electron transfer. Thus, both direct electron transfer and mediated electron transfer routes are modeled and concluded. We also explore the biocompatibility and synergistic effects of electrode materials, which emerge in combination with tuned enzymes and microbes to improve catalytic performance. The system by integrating solar energy driven photo-electrochemical technics with bio-catalysis is further discussed. We finally highlight the significant findings and perspectives that have provided strong foundations for the remarkable development of green and sustainable bioelectrocatalysis for CO₂ reduction, and that offer a blueprint for C_n valuable products originate from CO₂ under efficient and mild conditions.

Investigating purification and activity analysis of urease enzyme extracted from jack bean source: A green chemistry approach

Urease is an enzyme of historical importance in the field of biochemistry, generally microbial and plant urease is the primary sources of urease. The significant applications of urease enzyme are found to be foremost in food industry, medical equipment's and biosensors. In this work, urease has been extracted from Jack bean meal using ammonium sulphate and acetone precipitation. A significant amount of urease was precipitated and concentrated at 60% saturated solution of ammonium sulphate. The obtained precipitates were dissolved in 50 mM phosphate buffer (pH 8) after centrifugation, and subjected to sodium dodecyl-sulphate polyacrylamide gel electrophoresis (SDS-PAGE) to determine the molecular weight of urease. Results obtained from the SDS-PAGE were validated using Zymography. Anion exchange chromatography was used to separate the desired protein at different pH (7.0, 7.5 and 8.0). The eluted fractions were assessed for urease activity using phenol-nitroprusside dependent ammonia release assay. Under these assay conditions, one unit of urease activity was calibrated as the amount of enzyme liberating 1 μM of NH3 from urea per unit time. The eluted fraction and Zymography analysis show the purified urease observed at 90 kDa and activity of purified urease, respectively. The obtained results for specific activity (173.67Units mg) and % purification (99.71%) for urease has been compared with the available literature, which are found to be in close relation with existing results. The proposed method is a novel approach which has recorded highest % purification and specific activity. Furthermore, it can be suitable for extracting urease from jack bean source for various industrial applications.

Peptide conformational imprints enhanced the catalytic activity of papain for esterification

Peptide conformational imprints (PCIs) offer a promising perspective to directly generate binding sites for preserving enzymes with high catalytic activity and stability. In this study, we synthesized a new chiral cross-linker cost-effectively for controlling the matrix morphology of PCIs on magnetic particles (PCIMPs) to stabilize their recognition capability. Meanwhile, based on the flank part of the sequences on papain (PAP), three epitope peptides were selected and synthesized. Molecularly imprinted polymers (MIPs) were then fabricated in the presence of the epitope peptide using our new cross-linker on magnetic particles (MPs) to generate PCIMPs. PCIMPs were formed with helical cavities that complement the PAP structure to adsorb specifically at the targeted position of PAP. PCIMPs^65–79 were found to have the best binding parameters to the PAP with K_d = 0.087 μM and B_max = 4.56 μM. Upon esterification of N-Boc-His-OH, proton nuclear magnetic resonance (¹H-NMR) was used to monitor the yield of the reaction and evaluate the activity of PAP/PCIMPs. The kinetic parameters of PAP/PCIMPs^65–79 were calculated as V_max = 3.0 μM s⁻¹, K_m = 5 × 10⁻² M, k_cat = 1.1 × 10^–1 s⁻¹, and k_cat/K_m = 2.2 M⁻¹ s⁻¹. In addition, PAP is bound tightly to PCIMPs to sustain its activity after four consecutive cycles.

Hydrophilic Nonwoven Nanofiber Membranes as Nanostructured Supports for Enzyme Immobilization

The high porosity, interconnected pore structure, and high surface area-to-volume ratio make the hydrophilic nonwoven nanofiber membranes (NV-NF-Ms) promising nanostructured supports for enzyme immobilization in different biotechnological applications. In this work, NV-NF-Ms with excellent mechanical and chemical properties were designed and fabricated by electrospinning in one step without using additives or complicated crosslinking processes after electrospinning. To do so, two types of ultrahigh-molecular-weight linear copolymers with very different mechanical properties were used. Methyl methacrylate-co-hydroxyethyl methacrylate (p(MMA)-co-p(HEMA)) and methyl acrylate-co-hydroxyethyl acrylate (p(MA)-co-p(HEA)) were designed and synthesized by reverse atom transfer radical polymerization (reverse-ATRP) and copper-mediated living radical polymerization (Cu0-MC-LRP), respectively. The copolymers were characterized by nuclear magnetic resonance (1H-NMR) spectroscopy and by triple detection gel permeation chromatography (GPC). The polarity, topology, and molecular weight of the copolymers were perfectly adjusted. The polymeric blend formed by (MMA)1002-co-(HEMA)1002 (M w = 230,855 ± 7418 Da; M n = 115,748 ± 35,567 Da; PDI = 2.00) and (MA)11709-co-(HEA)7806 (M w = 1.972 × 106 ± 33,729 Da; M n = 1.395 × 106 ± 35,019 Da; PDI = 1.41) was used to manufacture (without additives or chemical crosslinking processes) hydroxylated nonwoven nanofiber membranes (NV-NF-Ms-OH; 300 nm in fiber diameter) with excellent mechanical and chemical properties. The morphology of NV-NF-Ms-OH was studied by scanning electron microscopy (SEM). The suitability for enzyme binding was proven by designing a palette of different surface functionalization to enable both reversible and irreversible enzyme immobilization. NV-NF-Ms-OH were successfully functionalized with vinyl sulfone (281 ± 20 μmol/g), carboxyl (560 ± 50 μmol/g), and amine groups (281 ± 20 μmol/g) and applied for the immobilization of two enzymes of biotechnological interest. Galactose oxidase was immobilized on vinyl sulfone-activated materials and carboxyl-activated materials, while laccase was immobilized onto amine-activated materials. These preliminary results are a promising basis for the application of nonwoven membranes in enzyme technology.

Is enzyme immobilization a mature discipline? Some critical considerations to capitalize on the benefits of immobilization

Enzyme immobilization has been developing since the 1960s and although many industrial biocatalytic processes use the technology to improve enzyme performance, still today we are far from full exploitation of the field. One clear reason is that many evaluate immobilization based on only a few experiments that are not always well-designed. In contrast to many other reviews on the subject, here we highlight the pitfalls of using incorrectly designed immobilization protocols and explain why in many cases sub-optimal results are obtained. We also describe solutions to overcome these challenges and come to the conclusion that recent developments in material science, bioprocess engineering and protein science continue to open new opportunities for the future. In this way, enzyme immobilization, far from being a mature discipline, remains as a subject of high interest and where intense research is still necessary to take full advantage of the possibilities.

A versatile biomimetic multienzyme cascade nanoplatform based on boronic acid-modified metal-organic framework for colorimetric biosensing

The combination of bio- and chemo-catalysts for sequential cascades has received considerable attention in analytical fields because of the regulable catalytic efficiency and selectivity under various physiological conditions. In this paper, a versatile multienzyme cascade nanoplatform with excellent activity for biosensing is demonstrated by combining metal-organic framework (MOF)-based nanozyme with natural enzymes. A boronic acid-modified MOF, MIL-100(Fe)-BA, was obtained via a microwave-assisted metal-ligand-fragment co-assembly strategy. On the one hand, MIL-100(Fe)-BA could serve as a nanozyme with dual oxidase/peroxidase bioactivity to detect glutathione and ascorbic acid with a detection limit of 0.12 μM and 0.09 μM, respectively. On the other hand, the hierarchically porous MIL-100(Fe)-BA possesses adequate recognition sites for immobilizing enzymes with acceptable protein leakage, enabling it to act like a scaffold for the fixation of a single enzyme (sarcosine oxidase) or bi-enzymes (acetylcholinesterase/choline oxidase) and guide a multienzyme cascade reaction system with high efficiency. The cascade nanoplatform has merits of both artificial nanozymes and natural enzymes, providing satisfactory sarcosine/acetylcholine sensing ability with detection limits of 0.26 μM and 1.18 μM. The developed catalytic system not only expands the application of nanozymes in tandem enzymatic bio-catalysis, but provides a facile and efficient multienzyme cascade nanoplatform for biosensing and other applications.

Biomimetic-mineralized bifunctional nanoflowers for enzyme-free and colorimetric immunological detection of protein biomarker

Detection of protein biomarkers relies largely on the development of modern immunological methods. Herein, a new enzyme-free immunological method is proposed to detect protein biomarkers. Employment of antibody-Cu₃(PO₄)₂ hybrid nanoflowers, which are prepared through a facile and mild biomimetic-mineralizing process, is the core concept of the method. These nanoflowers can perform functions: one is to bind to target protein biomarkers with high specificity; the other is to release large amounts of Cu²⁺ upon acid treatment, which can interact with creatinine and exert peroxidase-mimicking enzyme activity, therefore producing a distinctly amplified signal. Using osteocalcin, a well-known circulating protein biomarker for bone formation, as a model, the method affords a linear range from 0.1 to 50 ng/mL with a detection limit of 0.042 ng/mL, which is superior to reported methods. Moreover, the method shows considerable specificity, desirable performance in serum samples and eliminates the use of enzymes, so a great potential for this method is expected to meet the need of the clinical diagnosis.

One-pot synthesis and biochemical characterization of a magnetic collagenase nanoflower and evaluation of its biotechnological applications

Recently, hierarchical magnetic enzyme nanoflowers have been found extensive attention for efficient enzyme immobilization due to high surface area, low mass transfer limitations, active site accessibility, promotion of the enzymatic performance, and facile reusing. Herein, we report the purification of the Bacillus collagenase and then synthesis of magnetic cross-linked collagenase-metal hybrid nanoflowers (mcCNFs). The catalytic efficiency (k_cat/K_m) value of the immobilized collagenase was 2.2 times more than that of the free collagenase. The collagenase activity of mcCNFs enhanced about 2.9 and 4.6 at 85 and 90 °C, respectively, compared to free collagenase. Thermal stability of mcCNFs increased about 31% and 24% after 3 h of incubation at 50 and 60 °C, respectively. After 10 cycles of reusing, the mCNFs collagenase showed 83% of its initial activity. Results showed that the mcCNFs revealed 1.4 times more activity than the free collagenase in 0.16% protein waste. Furthermore, the hydrolysis value of chicken pie protein wastes by the immobilized enzyme obtained 4 times more than the free collagenase after 240 min incubation at 40 °C. Finally, our results showed that the construction of mcCNFs is an efficient method to increase the enzymatic performance and has excessive potential for the hydrolysis of protein wastes in the food industry.