The Cytotoxicity, DNA Fragmentation, and Decreasing Velocity Induced By Chromium(III) Oxide on Rainbow Trout Spermatozoa.

The present study aimed to determine the cytotoxicity of chromium(III) oxide micro particles (Cr2O3-Ps) in rainbow trout (Oncorhynchus mykiss) spermatozoa. Firstly, Cr2O3-Ps were synthesized and structurally characterized the surface, morphological for particle size and thermal properties. In addition, its structural and elemental purity was determined using energy-dispersive X-ray (EDX) spectrum and elemental maps. Structural purity, thermal properties, and stability of Cr2O3-Ps were also examined in detail by performing thermal analysis techniques. The cytotoxicity of Cr2O3-Ps was measured by the observation of velocities, antioxidant activities, and DNA damages in rainbow trout spermatozoa after exposure during 3 h in vitro incubation. The straight line velocity (VSL), the curvilinear velocity (VCL), and the angular path velocity (VAP) of spermatozoa decreased after exposure to Cr2O3-Ps. While the superoxide dismutase (SOD) and the catalase (CAT) decreased, the lipid peroxidation increased in a dose-dependent manner. However, the total glutathione (tGSH) was not affected in this period. DNA damages were also determined in spermatozoa using Comet assay. According to DNA in tail (%) data, DNA damages have been detected with gradually increasing concentrations of Cr2O3-Ps. Furthermore, all of class types which are categorized as the intensity of DNA fragmentation has been observed between 50 and 500 µg/L concentrations of Cr2O3-Ps exposed to rainbow trout spermatozoa. At the end of this study, we determined that the effective concentrations (EC50) were 76.67 µg/L for VSL and 87.77 µg/L for VCL. Finally, these results about Cr2O3-Ps may say to be major risk concentrations over 70 µg/L for fish reproduction in aquatic environments.

Effects of Yttrium Doping on Erbium-Based Hydroxyapatites: Theoretical and Experimental Study.

This is the first investigation of yttrium (Y) and erbium (Er) co-doped hydroxyapatite (HAp) structures, conducted using theoretical and experimental procedures. By using a wet chemical method, the materials were synthesized by varying the concentration of Y amounts of 0.13, 0.26, 0.39, 0.52, 0.65, and 0.78 at.% every virtual 10 atoms of calcium, whereas Er was kept fixed at 0.39 at.%. Spectroscopic, thermal, and in vitro biocompatibility testing were performed on the generated samples. Theoretical calculations were carried out to compute the energy bandgap, density of states, and linear absorption coefficient. The effects of Y concentration on thermal, morphological, and structural parameters were investigated in detail. Raman and Infrared (FTIR) spectroscopies confirmed the formation of the HAp structure in the samples. Theoretical investigations indicated that the increasing amount of Y increased the density from 3.1724 g cm-3 to 3.1824 g cm-3 and decreased the bandgap energy from 4.196 eV to 4.156 eV, except for the sample containing 0.39 at. % of the dopant, which exhibited a decrease in the bandgap. The values of linear absorption appeared reduced with an increase in photon energy. The samples exhibited cell viability higher than 110%, which revealed excellent biocompatibility for biological applications of the prepared samples.

Fast Curing Multifunctional Tissue Adhesives of Sericin-Based Polyurethane-Acrylates for Sternal Closure.

The use of wire cerclage after sternal closure is the standard method because of its rigidity and strength. Despite this, they have many disadvantages such as tissue trauma, operator-induced failures, and the risk of infection. To avoid complications during sternotomy and promote tissue regeneration, tissue adhesives should be used in post-surgical treatment. Here, we report a highly biocompatible, biomimetic, biodegradable, antibacterial, and UV-curable polyurethane-acrylate (PU-A) tissue adhesive for sternal closure as a supportive to wire cerclage. In the study, PU-As were synthesized with variable biocompatible monomers, such as silk sericin, polyethylene glycol, dopamine, and an aliphatic isocyanate 4,4'-methylenebis(cyclohexyl isocyanate). The highest adhesion strength was found to be 4322 kPa, and the ex vivo compressive test result was determined as 715 kPa. The adhesive was determined to be highly biocompatible (on L-929 cells), biodegradable, and antibacterial (on Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus bacteria). Finally, after opening the sternum of rats, the adhesive was applied to bond the bones and cured with UV for 5 min. According to the results, there was no visible inflammation in the adhesive groups, while some animals had high inflammation in the cyanoacrylate and wire cerclage groups. These results indicate that the adhesive may be suitable for sternal fixation by preventing the disadvantages of the steel wires and promoting tissue healing.

Chemistry and engineering of brush type polymers: Perspective towards tissue engineering.

In tissue engineering, it is imperative to control the behaviour of cells/stem cells, such as adhesion, proliferation, propagation, motility, and differentiation for tissue regeneration. Surfaces that allow cells to behave in this way are critical as support materials in tissue engineering. Among these surfaces, brush-type polymers have an important potential for tissue engineering and biomedical applications. Brush structure and length, end groups, bonding densities, hydrophilicity, surface energy, structural flexibility, thermal stability, surface chemical reactivity, rheological and tribological properties, electron and energy transfer ability, cell binding and absorption abilities for various biological molecules of brush-type polymers were increased its importance in tissue engineering applications. In addition, thanks to these functional properties and adjustable surface properties, brush type polymers are used in different high-tech applications such as electronics, sensors, anti-fouling, catalysis, purification and energy etc. This review comprehensively highlights the use of brush-type polymers in tissue engineering applications. Considering the superior properties of brush-type polymer structures, it is believed that in the future, it will be an effective tool in structure designs containing many different biomolecules (enzymes, proteins, etc.) in the field of tissue engineering.

Interaction of nickel ferrite nanoparticles with nucleic acids.

In this article, we introduced an electrochemical biosensor employing graphite electrodes (GE) decorated with Nickel ferrite (NiFe2O4) nanoparticles for nucleic acid detection. NiFe2O4 nanoparticles in a narrow size distribution were synthesized with co-precipitation technique. Their chemical and crystallographic properties were characterized with FTIR and X-ray spectroscopies. Nanoparticle size distribution and hydrodynamic diameter were determined with particle size analyzer. Elemental content and purity of nanoparticles were analyzed with EDX analysis. Our analyses showed a diameter of ~10 nm for NiFe2O4 nanoparticles. Electrochemical properties of NiFe2O4 nanoparticles were examined with different analysis methods. Conductivity properties of NiFe2O4 nanoparticles were investigated with Cyclic Voltammetry (CV), which confirmed that nanoparticles on GE surface have a high surface area and conductivity. More importantly, in this article, the interactions between NiFe2O4 nanoparticles and double stranded DNA (dsDNA), single stranded DNA (ssDNA), and RNA were for the first time examined using Differential Pulse Voltammetry (DPV), CV, and Electrochemical Impedance Spectroscopy (EIS). Oxidation peak currents of NiFe2O4 nanoparticles and guanine bases of dsDNA, ssDNA, and RNA showed that NiFe2O4 nanoparticles effectively interacts with nucleic acids via an electrostatic mode.

Photocrosslinkable gelatin/collagen based bioinspired polyurethane-acrylate bone adhesives with biocompatibility and biodegradability.

Hard or soft tissue adhesives have been presented as a promising candidate to replace traditional wound closure methods. However, there are mechanical strength problems in biological adhesives and biocompatibility problems in synthetic-based adhesives. At this point, we aimed to remove all these disadvantages and produce a single adhesive that contains all the necessary features and acrylate functionalized UV-curable polyurethane formulations were produced with high crosslink density, high adhesion strength, biocompatibility and injectable property for easy application as potential biomedical adhesives. Aliphatic isophorone diisocyanate (IPDI) was used as the isocyanate source and ß-cyclodextrin was used for host-guest relationship with gentamicin by crosslinking. Proteins (gelatin (GEL), collagen (COL)) and PEGs of various molecular weight ranges (P200, P400, P600) were selected as the polyol backbone for polyurethane synthesis due to their multiple biological activities such as biocompatibility, biodegradability, biomimetic property. Several techniques have been used to characterize the structural, thermal, morphological, and various other physicochemical properties of the adhesive formulations. Besides, the possibility of its use as a hard tissue adhesive was investigated by evaluating the tissue adhesion strength in vitro and ex vivo via a universal testing analyzer in tensile mode. Corresponding adhesive formulations were evaluated by in vitro and in vivo techniques for biocompatibility. The best adhesion strength results were obtained as 3821.0 ±â€¯214.9, and 3722.2 ±â€¯486.8 kPa, for IPDI-COL-P200 and IPDI-GEL-P200, respectively. Good antibacterial activity capability toward Escherichia coli Pseudomonas aeruginosa, and Staphylococcus aureus were confirmed using disc diffusion method. Moreover, cell viability assay demonstrated that the formulations have no significant cytotoxicity on the L929 fibroblast cells. Most importantly, we finally performed the in vivo biodegradability and in vivo biocompatibility evaluations of the adhesive formulations on rat model. Considering their excellent cell/tissue viability, fast curable, strong adhesion, high antibacterial character, and injectability, these adhesive formulations have significant potential for tissue engineering applications.

Recent Progress and Perspectives on Polyurethane Membranes in the Development of Gas Sensors.

In today's technology, gas sensors are of great importance in areas such as assessing environmental impacts, monitoring gas production facilities, measuring natural gas, controlling mines and gas leaks. Improving sensor sensitivity and decreasing the determination time is among the subjects that are continuously investigated. The use of polymeric membranes to make such improvements is common practice in the gas sensor field. By the development of polymeric membrane-based gas sensors and increasing the measurement sensitivity, accurate, sensitive, precise and fast measurements of toxic gases, volatile organic gases, and trace gases have been possible. Therefore, polyurethane membranes have been promising in the development of next-generation gas sensors based on membrane diffusion to ensure real-time and continuous monitoring of gases in industry and academic studies. This study aims to evaluate, compare and discuss the recent developments in the use of polyurethane membranes in existing gas detection technologies with chemical, electrical and optical measurement methods. In these measurement methods, polyurethane structures act as a selectively permeable membrane, an ideal matrix material for conductive additives or a suitable film structure for coating the conductive polymeric films. Conductive additives or conductive film structures for gas sensors play an important role in the detection of the gas structure with the change in electrical properties during the passage of gas molecules. This review has focused on important properties such as selectivity, detection time and measurement sensitivity concerning gas detection technology containing polyurethane, which has been used so far.

Determination of characterization, antibacterial and drug release properties of POSS-based film synthesized with sol-gel technique.

In the study, antibacterial film synthesis was aimed using sol-gel technique from POSS structure with various functional groups. For this purpose, antibacterial properties have been acquired by metronidazole to the films to be synthesized. The films obtained were coated on glass surface samples by dip coating method. Antibacterial activities of surface coated glass samples were observed in E.coli and S. aureus bacteria. Metronidazole release studies in the film samples were followed by UV spectrophotometer. It was observed that drug release reached 68.90% at the end of the 24th h. As a result, it is thought that the synthesized film will be a good candidate especially for biomedical surface coating areas.

Chemistry, Structures, and Advanced Applications of Nanocomposites from Biorenewable Resources.

Researchers have recently focused on the advancement of new materials from biorenewable and sustainable sources because of great concerns about the environment, waste accumulation and destruction, and the inevitable depletion of fossil resources. Biorenewable materials have been extensively used as a matrix or reinforcement in many applications. In the development of innovative methods and materials, composites offer important advantages because of their excellent properties such as ease of fabrication, higher mechanical properties, high thermal stability, and many more. Especially, nanocomposites (obtained by using biorenewable sources) have significant advantages when compared to conventional composites. Nanocomposites have been utilized in many applications including food, biomedical, electroanalysis, energy storage, wastewater treatment, automotive, etc. This comprehensive review provides chemistry, structures, advanced applications, and recent developments about nanocomposites obtained from biorenewable sources.

Chitosan/polypropylene glycol hydrogel composite film designed with TiO2 nanoparticles: A promising scaffold of biomedical applications.

The present study explores the preparation and characterization of chitosan/poly (propylene glycol)/titanium dioxide (CH/PPG/TiO2) composite hydrogels in view of their developing applications such as antimicrobial packaging, wound dressing and antibacterial materials. The prepared CH/PPG/TiO2 films were comprehensively characterized by several methods. The size distribution showed the average size of the TiO2 nanoparticles (NPs) was about 40 nm. Additionally, other properties including swelling ratio, water retention, water contact angle, porosity, water uptake, in vitro enzymatic degradation, water vapor transmission rate, in vitro biomineralization studies, and mechanical tests were evaluated in detailed. Besides these characterizations, the antimicrobial activity of CH/PPG/TiO2 composite film against Staphylococcus aureus, Escherichia coli, and Candida lipolytica was evaluated by using disc diffusion method. Based on the obtained results, the CH/PPG/TiO2 composite hydrogels showed enhanced water vapor permeability, porosity, water retention, and swelling ratio. An improvement was observed in the examined mechanical and thermal properties with the addition of TiO2 NPs. The tensile strength and elongation at break values of CH/PPG/TiO2 were 3.0 MPa and 31%, respectively. Most importantly, the CH/PPG/TiO2 composite hydrogels showed strong antimicrobial properties. Finally, the developed composite scaffold prepared in this study may possess potentially useful in biomedical applications.

Assessing short-term effects of magnetite ferrite nanoparticles on Daphnia magna.

Magnetic nanoparticles (MNPs) are used in a wide range of sectors ranging from electronics to biomedicine, as well as in eutrophicated lake restoration due to their high P, N, and heavy metal adsorption capacity. This study assessed the effects of MNPs on mortality and morphometric changes of D. magna. According to the SEM, the synthesised MNPs were found to have spherical nanoparticles, be uniformly distributed, and have a homolithic size distribution of 50-110 nm. The EDX spectra confirmed the elemental structure and purities of these MNPs. A total of 396 neonates were used for short-term bioassays (96 h) through the MNPs in the laboratory (16:8 photoperiod). Experiments were applied in triplicate for each concentration of CuFe2O4, CoFe2O4, and NiFe2O4 MNPs and their respective control groups. Mortality and morphological measurements of each individual were recorded every 24 h. In the probit analysis, the 96-h LC50 (p < 0.05) for CuFe2O4, CoFe2O4, and NiFe2O4 MNPs was calculated to be 1.455 mg L-1, 39.834 mg L-1, and 21.730 mg L-1, respectively. CuFe2O4 MNPs were found to be more toxic than the other two MNPs. The concentrations of CuFe2O4, CoFe2O4, and NiFe2O4 MNPs drastically affected life span and morphologic growth of D. magna as a result of a short time exposure. The results of this study are useful for assessing what risks they pose to freshwater ecosystems.

Melatonin protects sperm cells of Capoeta trutta from toxicity of titanium dioxide nanoparticles.

In this study, it was aimed to determine the protective effects of melatonin (0.01, 0.1, and 1 mM) against 10 mg/L titanium dioxide nanoparticles (TiO2-NPs) on kinematic and oxidative indices in the sperm cells of Capoeta trutta. Therefore, TiO2 nanoparticles were synthesized primarily within the scope of the study. The synthesized nanoparticles were characterized by structurally different techniques. Then, melatonin and TiO2 were applied to Capoeta trutta sperm cells by in vitro. According to our data, all doses of melatonin showed protective effects on all velocities of sperm cells such as the straight line velocity (VSL), the curvilinear velocity (VCL), and the angular path velocity (VAP) against TiO2-NPs, while 0.1 and 1 mM doses of melatonin improved the VSL value. Although TiO2-NPs increased total glutathione (tGSH), malondialdehyde (MDA) lipid peroxidation, and superoxide dismutase (SOD) compared to the control group, there were positive treatment effects for all doses of melatonin on antioxidant capacity of sperm cells. At the end of this research, it is suggested that over 0.1 mM dose of melatonin improves the velocity of sperm cells and it plays a protective role against the toxic effects of TiO2-NPs.

Laccase-conjugated thiolated chitosan-Fe3O4 hybrid composite for biocatalytic degradation of organic dyes.

In this study, a novel immobilization support for laccase was developed to enhance enzyme stability, efficiency and reusability. Firstly, Fe3O4 magnetic particles were synthesized and modified by the co-precipitation route using thiolated chitosan (TCS). The support was characterized using several methods. Afterward, laccase was attached to the surface of functional support. The biochemical properties of the immobilized laccase were comprehensively investigated. It was observed that immobilized laccase achieved maximum activity at pH 4.0 and the optimum temperature was found to be 50 °C. After storage at +4 °C and ~25 °C for 4 weeks, the residual activity of the immobilized laccase was 87% and 80% of its initial activity, respectively. At 55 °C, the activity of immobilized laccase decreased to 73.4% in 180 min and after reused 20 times, the relative activity of immobilized laccase still was approximately 50% of its initial activity. Moreover, the textile dye (Reactive Blue 171 and Acid Blue 74) decolorization activity of immobilized laccase was also tested and it showed long-term textile dye decolorization activity. These results are promising for the use of laccase in industrial and biotechnological applications. Therefore, this functionalized magnetic hybrid composite might be used to immobilize laccase, an industrially important enzyme.

Investigation of toxic effects of amorphous SiO2 nanoparticles on motility and oxidative stress markers in rainbow trout sperm cells.

In this study, we investigated the effects of SiO2 nanoparticles (SiO2-NPs) (1, 10, 25, 50, and 100 mg/L) for 24 h in vitro on the motility parameters and oxidative stress markers such as total glutathione (TGSH), catalase (CAT), and malondialdehyde (MDA) of rainbow trout, Oncorhynchus mykiss sperm cells. Therefore, SiO2-NPs were synthesized with sol-gel reaction from tetraethoxy orthosilicate (TEOS). The prepared nanoparticle structures were characterized for chemical structure, morphology and thermal behavior employing Fourier transform infrared spectroscopy, X-ray spectroscopy, scanning electron micrograph, and thermal analysis (DTA/TGA/DSC) techniques. After exposure, there was statistically significant (p < 0.05) decreases in velocities of sperm cells. CAT activity significantly (p < 0.05) decreased by 9.6% in sperm cell treated with 100 mg/L. In addition, MDA level significantly increased by 70.4% and 77.5% in sperm cell treated with 50 and 100 mg/L SiO2-NPs, respectively (p < 0.05). These results showed that SiO2-NPs may have toxic effect on rainbow trout sperm cells in 50 mg/L and more.

Chloro-Modified Magnetic Fe3O4@MCM-41 Core-Shell Nanoparticles for L-Asparaginase Immobilization with Improved Catalytic Activity, Reusability, and Storage Stability.

This paper describes a new support that permits to efficient immobilization of L-asparaginase (L-ASNase). For this purpose, Fe3O4 magnetic nanoparticles were synthesized and coated by MCM-41. 3-chloropropyltrimethoxysilane (CPTMS) was used as a surface modifying agent for covalent immobilization of L-ASNase on the magnetic nanoparticles. The chemical structure; thermal, morphological, and magnetic properties; chemical composition; and zeta potential value of Fe3O4@MCM-41-Cl were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), differential scanning calorimetry (DSC), vibrating sample magnetometer (VSM), scanning electron microscope (SEM), energy dispersive X-ray (EDX), X-ray diffraction patterns (XRD), and zeta-potential measurement. The immobilization efficiency onto Fe3O4@MCM-41-Cl was detected as 63%. The reusability, storage, pH, and thermal stabilities of the immobilized L-ASNase were investigated and compared to that of soluble one. The immobilized enzyme maintained 42.2% of its original activity after 18 cycles of reuse. Furthermore, it was more stable towards pH and temperature compared with soluble enzyme. The Michaelis-Menten kinetic properties of immobilized L-ASNase showed a lower Vmax and a similar Km compared to soluble L-ASNase. Immobilized enzyme had around 47 and 32.5% residual activity upon storage a period of 28 days at 4 and 25 °C, respectively. In conclusion, the Fe3O4@MCM-41-Cl@L-ASNase core-shell nanoparticles could successfully be used in industrial and medical applications.

The Toxicity Assessment of Iron Oxide (Fe3O4) Nanoparticles on Physical and Biochemical Quality of Rainbow Trout Spermatozoon.

The aim of this study was to evaluate the in vitro effect of different doses (50, 100, 200, 400, and 800 mg/L) of Fe3O4 nanoparticles (NPs) at 4 °C for 24 h on the kinematics of rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) spermatozoon. Firstly, Fe3O4 NPs were prepared at about 30 nm from Iron (III) chloride, Iron (II) chloride, and NH3 via a co-precipitation synthesis technique. Then, the prepared Fe3O4 NPs were characterized by different instrumental techniques for their chemical structure, purity, morphology, surface properties, and thermal behavior. The size, microstructure, and morphology of the prepared Fe3O4 NPs were studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) spectroscopy, and scanning electron microscopy (SEM) equipped with an energy-dispersive X-ray spectrometer (EDS). The thermal properties of the Fe3O4 NPs were determined with thermogravimetric analysis (TGA), differential thermal analysis (DTA), and differential scanning calorimeter (DSC) analysis techniques. According to our results, there were statistically significant (p < 0.05) decreases in the velocities of spermatozoon after treatment with 400 mg/L Fe3O4 NPs. The superoxide dismutase (SOD) and catalase (CAT) activities were significant (p < 0.05) decrease after 100 mg/L in after exposure to Fe3O4 NPs in 24 h. As the doses of Fe3O4 NPs increases, the level of malondialdehyde (MDA) and total glutathione (tGSH) significantly (p < 0.05) increased at doses of 400 and 800 mg/L.

The in vitro toxicity analysis of titanium dioxide (TiO2) nanoparticles on kinematics and biochemical quality of rainbow trout sperm cells.

In recent years, titanium dioxide (TiO2) nanoparticles (NPs) as metal oxide nanoparticles are widely used in industry, agriculture, personal care products, cosmetics, sun protection and toothpaste, electronics, foodstuffs and food packaging. This use of nano-TiO2 has been associated with environmental toxicity concerns. Therefore, the aim of this study was to evaluate the in vitro effect of different doses of TiO2 NPs (∼30-40 nm) (0.01, 0.1, 0.5, 1, 10 and 50 mg/L) at 4oC for 3 h on the sperm cell kinematics as velocities of Rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) sperm cells. Furthermore, oxidative stress markers (total glutathione (TGSH) and superoxide dismutase (SOD) were assessed in sperm cells after exposure to TiO2 NPs. According to the obtained results, there were statistically significant (P < 0.05) decreasing in the velocities of sperm cells after 10 mg/L TiO2 NPs and an increase the activity of SOD (P < 0.05) and TGSH levels were determined.

Magnetic Fe3O4@MCM-41 core-shell nanoparticles functionalized with thiol silane for efficient l-asparaginase immobilization.

l-Asparaginase (l-ASNase) is a vital enzyme for medical treatment and food industry. Here, we assessed the use of Fe3O4@Mobil Composition of Matter No. 41 (MCM-41) magnetic nanoparticles as carrier matrix for l-ASNase immobilization. In addition, surface of Fe3O4@MCM-41 magnetic nanoparticles was functionalized with 3-mercaptopropyltrimethoxysilane (MPTMS) to enhance stability of l-ASNase. The chemical structure, thermal properties, magnetic profile and morphology of the thiol-functionalized Fe3O4@MCM-41 magnetic nanoparticles were characterized with Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), differential scanning calorimetry (DSC), vibrating sample magnetometer (VSM), scanning electron microscope (SEM), energy dispersive X-ray (EDX) spectroscopy and zeta-potential measurement. l-ASNase was covalently immobilized onto the thiol-functionalized Fe3O4@MCM-41 magnetic nanoparticles. The properties of the immobilized enzyme, including optimum pH, temperature, kinetic parameters, thermal stability, reusability and storage stability were investigated and compared to free one. Immobilized enzyme was found to be stable over a wide range of pH and temperature range than free enzyme. The immobilized l-ASNase also showed higher thermal stability after 180 min incubation at 50 °C. The immobilized enzyme still retained 63% of its original activity after 16 times of reuse. The Km value for the immobilized enzyme was 1.15-fold lower than the free enzyme, which indicates increased affinity for the substrate. Additionally, the immobilized enzyme was active over 65% and 53% after 30 days of storage at 4 °C and room temperature (∼25 °C), respectively. Thereby, the results confirmed that thiol-functionalized Fe3O4@MCM-41 magnetic nanoparticles had high efficiency for l-ASNase immobilization and improved stability of L-ASNase.

Design of epoxy-functionalized Fe3O4@MCM-41 core-shell nanoparticles for enzyme immobilization.

The scope of our research was to prepare the organosilane-modified Fe3O4@MCM-41 core-shell magnetic nanoparticles, used for L-ASNase immobilization and explored screening of immobilization conditions such as pH, temperature, thermal stability, kinetic parameters, reusability and storage stability. In this content, Fe3O4 core-shell magnetic nanoparticles were prepared via co-precipitation method and coated with MCM-41. Then, Fe3O4@MCM-41 magnetic nanoparticles were functionalized by (3-glycidyloxypropyl) trimethoxysilane (GPTMS) as an organosilane compound. Subsequently, L-ASNase was covalently immobilized on epoxy-functionalized Fe3O4@MCM-41 magnetic nanoparticles. The immobilized L-ASNase had greater activity at high pH and temperature values. It also maintained >92% of the initial activity after incubation at 55 °C for 3 h. Regarding kinetic values, immobilized L-ASNase showed a higher Vmax and lower Km compared to native L-ASNase. In addition, it displayed excellent reusability for 12 successive cycles. After 30 days of storage at 4 °C and 25 °C, immobilized L-ASNase retained 54% and 26% of its initial activities while native L-ASNase lost about 68% and 84% of its initial activity, respectively. As a result, the immobilization of L-ASNase onto magnetic nanoparticles may provide an advantage in terms of removal of L-ASNase from reaction media.

Magnetic-propelled Fe3O4-chitosan carriers enhance l-asparaginase catalytic activity: a promising strategy for enzyme immobilization.

Magnetic-propelled carriers comprising magnetic Fe3O4-chitosan nanoparticles were immobilized with l-asparaginase (l-ASNase). The enzyme displayed enhanced catalytic activity in a weak magnetic field, and thermal and pH stabilities. The conjugated l-ASNase presented higher thermostability and wider range of pH stability in comparison with those of free l-ASNase. Moreover, the reusability of conjugated l-ASNase significantly improved after immobilization and it retained 60.5% of its initial activity after undergoing 16 cycles. The conjugated l-ASNase maintained more than 50% and 48% initial activity after 4 weeks of storage at 4 °C and room temperature, respectively. Furthermore, we reveal that the activity of conjugated l-ASNase onto magnetic Fe3O4-chitosan particles increased by about 3-fold in the weak magnetic field at certain frequencies and flux density compared with that of free l-ASNase. Considering these excellent attributes, the magnetic-propelled mechanism in the transporting and activation of l-ASNase can be used by enhancing the catalytic activity, stability, and efficiency in vital implications for medicinal biotechnology.