Surface modification of magnetic nanoparticles with alkoxysilanes and their application in magnetic bioseparations

Propitious catalytic response of immobilized α-amylase from G. thermoleovorans in modified APTES-Fe3O4 NPs for industrial bio-processing

Challenges in enzyme and product recovery are currently intriguing in modern biotechnology. Coping enzyme stability, shelf life and efficiency, nanomaterials-based immobilization were epitomized of industrial practice. Herein, a α-amylase from Geobacillus thermoleovorans was purified and bound effectively on to a modified 3-Aminopropyltriethoxysilane (APTES)-Fe3O4 nanoparticle. It was revealed that the carrier-bound enzyme catalysis (pH 8 and 60 °C) was significant in contrast to the free enzyme (pH 7.5 and 55 °C). Furthermore, Zn2+ and Cu2+ were shown to cause inhibitory effects in both enzyme states. Unlike chloroform, toluene, benzene, and butanol, minimal effects were observed with ethanol, acetone, and hexane. The bound enzyme retained 27.4 % of its initial activity after being stored for 36 days. In addition, the reusability of the bound enzyme showed a gradual decline in activity after the first cycle; however, after 13 cycles, its residual activity at 53 % was observed. These data proved significant enough to use this enzyme for industrial starch and analogous substrate bio-processing.

Efficient Chlorostannate Modification of Magnetite Nanoparticles for Their Biofunctionalization

Magnetite nanoparticles (MNPs) are highly favored materials for a wide range of applications, from smart composite materials and biosensors to targeted drug delivery. These multifunctional applications typically require the biofunctional coating of MNPs that involves various conjugation techniques to form stable MNP-biomolecule complexes. In this study, a cost-effective method is developed for the chlorostannate modification of MNP surfaces that provides efficient one-step conjugation with biomolecules. The proposed method was validated using MNPs obtained via an optimized co-precipitation technique that included the use of degassed water, argon atmosphere, and the pre-filtering of FeCl2 and FeCl3 solutions followed by MNP surface modification using stannous chloride. The resulting chlorostannated nanoparticles were comprehensively characterized, and their efficiency was compared with both carboxylate-modified and unmodified MNPs. The biorecognition performance of MNPs was verified via magnetic immunochromatography. Mouse monoclonal antibodies to folic acid served as model biomolecules conjugated with the MNP to produce nanobioconjugates, while folic acid-gelatin conjugates were immobilized on the test lines of immunochromatography lateral flow test strips. The specific trapping of the obtained nanobioconjugates via antibody-antigen interactions was registered via the highly sensitive magnetic particle quantification technique. The developed chlorostannate modification of MNPs is a versatile, rapid, and convenient tool for creating multifunctional nanobioconjugates with applications that span in vitro diagnostics, magnetic separation, and potential in vivo uses.

Movements of Magnetite-Encapsulated Graphene Particles at Air-Water Interface and Their Cell Growths under Dynamic Magnetic Field

The motion of magnetic particles under magnetic fields is an object to be solved in association with basic and practical phenomena. Movement phenomena of magnetite-encapsulated graphene particles at air-water interfaces were evaluated by manufacturing a feedback control system of the magnetic field to cause the motion of particles due to magnetic torque. A homogeneous magnetic field was generated using two pairs of electromagnets located perpendicular to each other, which were connected to an electronic switch. The system influenced the translational movement and the self-rotational speed of magnetic particles located at a center on the surface of fluid media in a continuous duty cycle. Operating the particle at a remote control in the same duty cycle at the air-water surface, the short and elongated magnetic particles successfully rotated. In addition, the rotational speed of the curved particle was slower than that of the elongated particle. The results indicate that the translational and self-rotational movements of magnetite-encapsulated graphene particles at the air-water interface under the external magnetic field are size- and shape-dependent for the speed and the direction. A short magnetic particle was used as a target particle to rotate on cancer cell lines, aiming to study the advantage of this method to induce the growth of HeLa cells. It was monitored for up to 4 days with and without magnetic particles by checking the viability and morphology of cells before and after the electromagnetic treatment. As an outcome, the movement of magnetic particles reduced the number of biological cells, at least on HeLa cells, but it was inactive on the viability of HeLa cells.

Modification of insulating oils and oil-based titanium dioxide nanofluids for transformers: a review

In the last decade, oil-based titanium dioxide nanofluids (TiO2 NFs) have gained immense interest due to their unique insulating properties and excellent thermal performance, which endow them with the potential for application in the field of modified insulating oils. A timely comparison, analysis and summary of recent advances in the preparation, characterization, and properties of different oil-based TiO2 NFs for oil-immersed power transformers will contribute to provide a useful reference for the subsequent development of such materials. Preparation methods are reviewed along with their merits and demerits. Characterization techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), optical microscopy (OM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectroscopy, thermally stimulated current (TSC), pulse electroacoustic technique (PEA), finite element analysis (FEA), fluorescence spectroscopy, Raman spectroscopy and zeta potential analysis are all applied to determine the crystal structure, particle size, surface function, surface charge and stability. Stabilization mechanisms are also discussed in detail. Some critical properties of oil-based TiO2 NFs under the application of different influencing factors such as base oils, crystal structure, size of nanoparticles, surface modifiers, mixing percentage, and aging environment are highlighted. Finally, the existing challenges and perspectives are presented for future research.

Quercetin@Gd3+ doped Prussian blue nanocubes induce the pyroptotic death of MDA-MB-231 cells: combinational targeted multimodal therapy, dual modal MRI, intuitive modelling of r1-r2 relaxivities

Quercetin (Qu), a potential bioflavonoid has gained considerable interest as a promising chemotherapeutic drug which can inhibit the proliferation of triple-negative breast cancer (TNBC) cells due to its regulation of the expression of tumor-suppressor gene metastasis and antioxidant property. Notably, Qu exhibits a very negligible cytotoxic effect on normal cells, even with high-dose treatment, while it is shows high affinity to TNBC. However, the efficiency of Qu is limited clinically due to its poor bioavailability, caused by its low aqueous solubility (2.15 μg mL^-1 at 25 °C), rapid gastrointestinal digestion and chemical instability in alkaline and neutral media. Herein, polydopamine (PDA)-coated, NH₂-PEG-NH₂ and hyaluronic acid (HA)-functionalized Gd³⁺-doped Prussian blue nanocubes (GPBNC) are reported as a multifunctional platform for the codelivery of Qu as a chemotherapeutic agent and GPBNC as a photodynamic (PDT) and photothermal (PTT) agent with improved therapeutic efficiency to overcome theses barriers. PDA, NH₂-PEG-NH₂ and HA stabilize GPBNC@Qu and facilitate bioavailability and active-targeting, while absorption of near infrared (NIR) (808 nm; 1 W cm^-2) induces PDT and PTT activities and dual T₁-T₂-weighted magnetic resonance imaging (MRI) with high relaxometric parameters (r₁ 10.06 mM^-1 s^-1 and r₂ 24.96 mM^-1 s^-1 at a magnetic field of 3 T). The designed platform shows a pH-responsive Qu release profile and NIR-induced therapeutic efficiency of ∼79% in 20 minutes of irradiation, wherein N-terminal gardermin D (N-GSDMD) and a P2X7-receptor-mediated pyroptosis pathway induces cell death, corroborating the up-regulation of NLRP3, caspase-1, caspase-5, N-GSDMD, IL-1β, cleaved Pannexin-1 and P2X7 proteins. More interestingly, the increasing relaxivity values of Prussian blue nanocubes with Gd³⁺ doping have been explained on the basis of Solomon-Bloembergen-Morgan theory, considering inner- and outer-sphere relaxivity, wherein crystal defects, coordinated water molecules, tumbling rate, metal to water proton distance, correlation time, magnetisation value etc. play a significant role. In summary, our study suggests that GPBNC could be a beneficial nanocarrier for theranostic purposes against TNBC, while our conceptual study clearly demonstrates the role of various factors in increasing relaxometric parameters.

Magnetic-responsive Covalent Adaptable Networks

Covalent adaptable networks (CANs) are reprocessable polymers whose structural arrangement is based on the recombination of dynamic covalent bonds. Composite materials prepared by incorporating magnetic particles into CANs attract much attention due to their remote and precise control, fast response speed, high biological safety and strong penetration of magnetic stimuli. These properties often involve magnetothermal effect and direct magnetic-field guidance. Besides, some of them can also respond to light, electricity or pH values. Thus, they are favorable for soft actuators since various functions are achieved such as magnetic-assisted self-healing (heating or at ambient temperature), welding (on land or under water), shape-morphing, and so on. Although magnetic CANs just start to be studied in recent two years, their advances are promised to expand the practical applications in both cutting-edge academic and engineering fields. This review aims to summarize recent progress in magnetic-responsive CANs, including their design, synthesis and application.

Ultrasound Study of Magnetic and Non-Magnetic Nanoparticle Agglomeration in High Viscous Media

Ultrasound attenuation spectroscopy has found wide application in the study of colloidal dispersions such as emulsions or suspensions. The main advantage of this technique is that it can be applied to relatively high concentration systems without sample preparation. In particular, the use of Epstein-Carhart-Allegra-Hawley's (ECAH) ultrasound scattering theory, along with experimental data of ultrasound velocity or attenuation, provide the method of estimation for the particle or droplet size from nanometers to millimeters. In this study, suspensions of magnetite and silica nanoparticles in high viscous media (i.e., castor oil) were characterized by ultrasound spectroscopy. Both theoretical and experimental results showed a significant difference in ultrasound attenuation coefficients between the suspensions of magnetite and silica nanoparticles. The fitting of theoretical model to experimental ultrasound spectra was used to determine the real size of objects suspended in a high viscous medium that differed from the size distributions provided by electron microscopy imaging. The ultrasound spectroscopy technique demonstrated a greater tendency of magnetic particles toward agglomeration when compared with silica particles whose sizes were obtained from the combination of experimental and theoretical ultrasonic data and were more consistent with the electron microscopy images.

Impact of immobilization strategies on the activity and recyclability of lipases in nanomagnetic supports

The use of enzymes immobilized on nanomagnetic supports has produced surprising results in catalysis, mainly due to the increase in surface area and the potential for recovery and reuse. However, the meticulous control of the process and difficulties in reproducibility have made industrial-scale applications unfeasible. Furthermore, the role of conjugation strategies in the catalytic activity and recycling of catalysts is unclear. Therefore, the objective of this study was to compare the conjugation of enzymes on nanomagnetic supports through physical adsorption (naked) or covalent bonding with mercaptopropyltrimethoxysilane (MPTS) and aminopropyltriethoxysilane (APTS) ligands. The free lipase obtained from Rhizomucor miehei was used as a model enzyme. Total protein and enzyme activity were determined using spectrophotometry (UV-Vis) and the p-nitrophenyl palmitate (p-NPP) hydrolysis method. The results indicated that a more significant enzyme surface loading does not always mean better immobilization success. The physical adsorption binding strategy had higher surface loading and low catalytic activity. On the other hand, covalent coupling with free NH2 had an excellent catalytic activity with very low surface loading. Finally, we show that recyclability can be improved with conjugation mediated by disulfide bonds. The findings presented here are essential for developing nanoconjugates with high enzymatic activity, which can guarantee the success of several industrial applications.

Polystyrene magnetic nanocomposite blend: An effective, facile, and economical alternative in oil spill removal applications

Finding an efficient and economical method to remediate oil spills on water is a priority worldwide. In this article, we propose a solution to this problem using polystyrene magnetic nanocomposite blends composed of polystyrene chains grafted on the surface of silica coated on iron oxide nanoparticles and polystyrene. The hydrophobic and oleophilic magnetic polymer nanocomposite collected oil from the water surface quickly and efficiently. However, when the magnetic polymer nanocomposite was blended with polystyrene, the resulting material also absorbed oil efficiently from the water surface. The blending technique made it easier to prepare the absorbent and dramatically decreased its cost. These new absorbents absorbed oil up to 5 times their own weight in only 5 minutes. The excellent hydrophobicity, low density, and easy magnetic separation makes these new absorbents a promising alternative to recover oil from spilled in fresh and marine water.

Simultaneous determination of dihydroxybenzene isomers in cosmetics by synthesis of nitrogen-doped nickel carbide spheres and construction of ultrasensitive electrochemical sensor

N-doped nickel carbide spheres (N-NiCSs) were synthesised for the first time by controlling the type of surfactant, surfactant-to-Ni molar ratio, reaction temperature, and reaction time. The morphology, composition, and electrochemical behaviour of the synthesised spheres revealed that the spheres presented a large specific surface area, abundant pores, and good conductivity, with excellent electrocatalytic performance. A glassy carbon electrode-modified with N-NiCSs was used for the simultaneous identification of hydroquinone (HQ), catechol (CC), and resorcinol (RS) utilising differential pulse voltammetry. The oxidation peaks of HQ, CC, and RS were observed at 9.8, 119, and 470 mV, respectively (vs. SCE). Under optimal conditions, the oxidation peak currents of HQ, CC, and RS were linear in the concentration ranges of 0.005-100 μM, 0.05-200 μM, and 5-500 μM, respectively. The detection limits of HQ, CC, and RS were 0.00152 μM, 0.015 μM, and 0.24 μM (S/N = 3), respectively. The sensitivities of HQ, CC, and RS were 4.635, 2.069, and 0.985 μA μM^-1 cm^-2 (S/N = 3), respectively. The fabricated sensor was successfully used to detect HQ, CC, and RS in hair dye, whitening cream, and local tap water samples. Moreover, the sensor presented a good repeatability, reproducibility, and stability during cosmetic testing and a relatively wide linear range, an ultralow detection limit, and an ultrahigh sensitivity.

Nanobiomechanical behavior of Fe3O4@SiO2and Fe3O4@SiO2-NH2nanoparticles over HeLa cells interfaces

In this work, we studied the impact of magnetic nanoparticles (MNPs) interactions with HeLa cells when they are exposed to high frequency alternating magnetic field (AMF). Specifically, we measured the nanobiomechanical properties of cell interfaces by using atomic force microscopy (AFM). Magnetite (Fe₃O₄) MNPs were synthesized by coprecipitation and encapsulated with silica (SiO₂): Fe₃O₄@SiO₂and functionalized with amino groups (-NH₂): Fe₃O₄@SiO₂-NH₂, by sonochemical processing. HeLa cells were incubated with or without MNPs, and then exposed to AMF at 37 °C. A biomechanical analysis was then performed through AFM, providing the Young's modulus and stiffness of the cells. The statistical analysis (p < 0.001) showed that AMF application or MNPs interaction modified the biomechanical behavior of the cell interfaces. Interestingly, the most significant difference was found for HeLa cells incubated with Fe₃O₄@SiO₂-NH₂and exposed to AMF, showing that the local heat of these MNPs modified their elasticity and stiffness.

Enrichment of low abundance DNA/RNA by oligonucleotide-clicked iron oxide nanoparticles

Detection of low abundance target DNA/RNA for clinical or research purposes is challenging because the target sequences can be hidden under a large background of human genomic or non-human metagenomic sequences. We describe a probe-based capture method to enrich for target sequences with DNA-clicked iron oxide nanoparticles. Our method was tested against commercial capture assays using streptavidin beads, on a set of probes derived from a common genotype of the hepatitis C virus. We showed that our method is more specific and sensitive, most likely due to the combination of an inert silica coating and a high density of DNA probes clicked to the nanoparticles. This facilitates target capture below the limits of detection for TaqMan qPCR, and we believe that this method has the potential to transform management of infectious diseases.

Nanoparticles Functionalised with Re(I) Tricarbonyl Complexes for Cancer Theranostics

Globally, cancer is the second (to cardiovascular diseases) leading cause of death. Regardless of various efforts (i.e., finance, research, and workforce) to advance novel cancer theranostics (diagnosis and therapy), there have been few successful attempts towards ongoing clinical treatment options as a result of the complications posed by cancerous tumors. In recent years, the application of magnetic nanomedicine as theranostic devices has garnered enormous attention in cancer treatment research. Magnetic nanoparticles (MNPs) are capable of tuning the magnetic field in their environment, which positively impacts theranostic applications in nanomedicine significantly. MNPs are utilized as contrasting agents for cancer diagnosis, molecular imaging, hyperfusion region visualization, and T cell-based radiotherapy because of their interesting features of small size, high reactive surface area, target ability to cells, and functionalization capability. Radiolabelling of NPs is a powerful diagnostic approach in nuclear medicine imaging and therapy. The use of luminescent radioactive rhenium(I), 188/186Re, tricarbonyl complexes functionalised with magnetite Fe3O4 NPs in nanomedicine has improved the diagnosis and therapy of cancer tumors. This is because the combination of Re(I) with MNPs can improve low distribution and cell penetration into deeper tissues.

Fabrication, Microstructure and Colloidal Stability of Humic Acids Loaded Fe3O4/APTES Nanosorbents for Environmental Applications

Nowadays, numerous researches are being performed to formulate nontoxic multifunctional magnetic materials possessing both high colloidal stability and magnetization, but there is a demand in the prediction of chemical and colloidal stability in water solutions. Herein, a series of silica-coated magnetite nanoparticles (MNPs) has been synthesized via the sol-gel method with and without establishing an inert atmosphere, and then it was tested in terms of humic acids (HA) loading applied as a multifunctional coating agent. The influence of ambient conditions on the microstructure, colloidal stability and HA loading of different silica-coated MNPs has been established. The XRD patterns show that the content of stoichiometric Fe₃O₄ decreases from 78.8% to 42.4% at inert and ambient atmosphere synthesis, respectively. The most striking observation was the shift of the MNPs isoelectric point from pH ~7 to 3, with an increasing HA reaching up to the reversal of the zeta potential sign as it was covered completely by HA molecules. The zeta potential data of MNPs can be used to predict the loading capacity for HA polyanions. The data help to understand the way for materials’ development with the complexation ability of humic acids and with the insolubility of silica gel to pave the way to develop a novel, efficient and magnetically separable adsorbent for contaminant removal.

Amino-based magneto-polymeric-modified mixed iron hydroxides for magnetic solid phase extraction of phenol residues in environmental samples

Mixed iron hydroxides (MIHs) modified with different amino-based polymeric materials, including aminopropyltriethoxysilane, polydopamine, diaminobenzoic acid, polyaniline, and polyphenylenediamine, were comparatively investigated as sorbents for the extraction of phenol compounds. Polyphenylenediamine-modified mixed iron hydroxides (MIH@PPDA) showed high adsorption capability for most target analytes. Its ferromagnetic behavior, with a magnetization of 17.38 emu g^-1, was sufficient for subsequent use in magnetic solid-phase extraction (MSPE). The functional groups, morphology, and magnetic properties of this magnetic nanomaterial were investigated using Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, X-ray diffraction, and CHN analysis. High-performance liquid chromatography with a photodiode array detector was used to quantify phenol compounds. The experimental parameters affecting the efficiency of the entire MSPE process were optimized. Good linearity in the range of 0.5-1000 µg L^-1 was obtained (depended on the compound). The detection and quantitation limits varied from 0.01 to 0.3 µg L^-1 and 0.03 to 0.9 µg L^-1, respectively. The enrichment factors for all phenol compounds were in the range of 80-285. The precision in terms of intra- and inter-day relative standard deviations were below 5.8% and 6.2%, respectively. The developed MSPE method was applied to analyze phenol compounds in diverse samples, including soil, drinking water, and fruit. Relative recoveries of 76.7-130.1% were obtained. The MIH@PPDA magneto-polymeric sorbent exhibits good stability and is reliable for a variety of phenol compounds.

APTES monolayer coverage on self-assembled magnetic nanospheres for controlled release of anticancer drug Nintedanib

The use of an appropriate delivery system capable of protecting, translocating, and selectively releasing therapeutic moieties to desired sites can promote the efficacy of an active compound. In this work, we have developed a nanoformulation which preserves its magnetization to load a model anticancerous drug and to explore the controlled release of the drug in a cancerous environment. For the preparation of the nanoformulation, self-assembled magnetic nanospheres (MNS) made of superparamagnetic iron oxide nanoparticles were grafted with a monolayer of (3-aminopropyl)triethoxysilane (APTES). A direct functionalization strategy was used to avoid the loss of the MNS magnetization. The successful preparation of the nanoformulation was validated by structural, microstructural, and magnetic investigations. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) were used to establish the presence of APTES on the MNS surface. The amine content quantified by a ninhydrin assay revealed the monolayer coverage of APTES over MNS. The monolayer coverage of APTES reduced only negligibly the saturation magnetization from 77 emu/g (for MNS) to 74 emu/g (for MNS-APTES). Detailed investigations of the thermoremanent magnetization were carried out to assess the superparamagnetism in the MNS. To make the nanoformulation pH-responsive, the anticancerous drug Nintedanib (NTD) was conjugated with MNS-APTES through the acid liable imine bond. At pH 5.5, which mimics a cancerous environment, a controlled release of 85% in 48 h was observed. On the other hand, prolonged release of NTD was found at physiological conditions (i.e., pH 7.4). In vitro cytotoxicity study showed dose-dependent activity of MNS-APTES-NTD for human lung cancer cells L-132. About 75% reduction in cellular viability for a 100 μg/mL concentration of nanoformulation was observed. The nanoformulation designed using MNS and monolayer coverage of APTES has potential in cancer therapy as well as in other nanobiological applications.

Triphenylphosphonium-functionalized nanocomposites as carriers of a platinum diimine complex for photodynamic therapy

The photodamage induced by PDT usually occurs at the site where the photosensitizers accumulate in the tumor cells, thus the modulation of intrinsic apoptosis by mitochondria-targeting PDT drugs might be a promising way to enhance the therapeutic efficacy of PDT drugs against tumor cells. Novel triphenylphosphonium-functionalized nanocomposites employed as carriers of a photoactive platinum diimine complex have been fabricated and characterized. Upon irradiation, the IC₅₀ value of photosensitizer-loaded triphenylphosphonium-functionalized nanocomposites was found to be 17.4 or 14.4 times lower than that of the photosensitizer studied alone against HCT116 cells or A549 cells, respectively. The results suggested that the triphenylphosphonium- functionalized nanocomposites as drug delivery vehicles could significantly enhance the photodynamic efficacy of the photosensitizer.

Biopolymers and nanostructured materials to develop pectinases-based immobilized nano-biocatalytic systems for biotechnological applications

Pectinases are the emerging enzymes of the biotechnology industry with a 25% share in the worldwide food and beverage enzyme market. These are green and eco-friendly tools of nature and hold a prominent place among the commercially produced enzymes. Pectinases exhibit applications in various industrial bioprocesses, such as clarification of fruit juices and wine, degumming, and retting of plant fibers, extraction of antioxidants and oil, fermentation of tea/coffee, wastewater remediation, modification of pectin-laden agro-industrial waste materials for high-value products biosynthesis, manufacture of cellulose fibres, scouring, bleaching, and size reduction of fabric, cellulosic biomass pretreatment for bioethanol production, etc. Nevertheless, like other enzymes, pectinases also face the challenges of low operational stability, recoverability, and recyclability. To address the above-mentioned problems, enzyme immobilization has become an eminently promising approach to improve their thermal stability and catalytic characteristics. Immobilization facilitates easy recovery and recycling of the biocatalysts multiple times, leading to enhanced performance and commercial feasibility.In this review, we illustrate recent developments on the immobilization of pectinolytic enzymes using polymers and nanostructured materials-based carrier supports to constitute novel biocatalytic systems for industrial exploitability. The first section reviewed the immobilization of pectinases on polymers-based supports (ca-alginate, chitosan, agar-agar, hybrid polymers) as a host matrix to construct robust pectinases-based biocatalytic systems. The second half covers nanostructured supports (nano-silica, magnetic nanostructures, hybrid nanoflowers, dual-responsive polymeric nanocarriers, montmorillonite clay), and cross-linked enzyme aggregates for enzyme immobilization. The biotechnological applications of the resulted immobilized robust pectinases-based biocatalytic systems are also meticulously vetted. Finally, the concluding remarks and future recommendations are also given.

Effect of engineered superparamagnetic iron oxide nanoparticles in targeted cardiac precursor cell delivery by MRI

A scientific approach is presented describing the fabrication of nanoprobe (GloTrack) that can act as cardiac precursor label to segregate cells from cardiac/non cardiac origins and traced by magnetic resonance imaging (MRI). Signal regulatory protein alpha (SIRPA) and kinase domain receptor (KDR) recognizing antibodies, form a layer on super paramagnetic iron oxide nanoparticle - poly-ethylene glycol (SPION-PEG) complex, and bind to protein expressed on the surface of cardiac muscle cells. Physical attributes size, distribution, labelling efficiency, echocardiogram (ECG) changes and bio-distribution by MRI were analysed. The results indicate that GloTrack has an average size of 471 nm, exhibits negative potential and promotes labelling efficiency. The bio-distribution of GloTrack in in vivo experiments was traceable in 7T MRI showing high accumulation of GloTrack in cardiac muscles as compared to the liver and spleen. ECG data revealed that GloTrack segregated cardiac precursors has the potential benefit in treating heart failure, thereby paving way in the development of minimal cell manipulation with targeted cell delivery approaches.

Application of magnetic nanomaterials in electroanalytical methods: A review

Magnetic nanomaterials (MNMs) have gained high attention in different fields of studies due to their ferromagnetic/superparamagnetic properties and their low toxicity and high biocompatibility. MNMs contain magnetic elements such as iron and nickel in metallic, bimetallic, metal oxide, and mixed metal oxide. In electroanalytical methods, MNMs have been applied as sorbents for sample preparation before the electrochemical detection (sorbent role), as the electrode modifier (catalytic role), and the integration of the above two roles (as both sorbent and catalytic agent). In this paper, the application of MNMs in electroanalytical methods have been classified based on the main role of the nanomaterial and discussed separately. Furthermore, catalytic activities of MNMs in electroanalytical methods such as redox electrocatalytic, nanozymes catalytic (peroxidase, catalase activity, oxidase activity, superoxide dismutase activity), catalyst gate, and nanocontainer have been discussed.

Highly biocompatible multifunctional hybrid nanoparticles based on Fe3O4 decorated nanodiamond with superior superparamagnetic behaviors and photoluminescent properties

The multifunctional nanostructures with superparamagnetic and luminescent properties undergo revolution in the field of bio-nanotechnology. In this article, we reported a facile and efficient one-step modified co-precipitation method to load superparamagnetic Fe₃O₄ nanoparticle on oxidized nanodiamond (Ox-ND). Subsequently, the as-prepared Ox-ND/Fe₃O₄ hybrid nanoparticle was surface functionalized with vinyltrimethoxysilane (VTMS) to enhance its compatibility with organic media. The structure, morphology, magnetic, and optical properties of the nanohybrid were systematically investigated. The results confirmed successful loading of crystalline Fe₃O₄ on the surface of Ox-ND. Ox-ND/Fe₃O₄ multifunctional hybrid nanoparticle presented strong superparamagnetism (with a saturation magnetization of 67 emu/g at room temperature) and photoluminescence (blue emission) with good chemical reactivity. PrestoBlue assay indicated great biocompatibility of silanized Ox-ND/Fe₃O₄ in MCF-7 cells even at high concentrations, e.g. 7.2 mg/mL. The hybrid nanoparticle synthesized in this study potentially opens doors for high contrast imaging and targeted delivery applications.

Superparamagnetic Iron Oxide Nanoparticles and Essential Oils: A New Tool for Biological Applications

Essential oils are complex mixtures of volatile compounds with diverse biological properties. Antimicrobial activity has been attributed to the essential oils as well as their capacity to prevent pathogenic microorganisms from forming biofilms. The search of compounds or methodologies with this capacity is of great importance due to the fact that the adherence of these pathogenic microorganisms to surfaces largely contributes to antibiotic resistance. Superparamagnetic iron oxide nanoparticles have been assayed for diverse biomedical applications due to their biocompatibility and low toxicity. Several methods have been developed in order to obtain functionalized magnetite nanoparticles with adequate size, shape, size distribution, surface, and magnetic properties for medical applications. Essential oils have been evaluated as modifiers of the surface magnetite nanoparticles for improving their stabilization but particularly to prevent the growth of microorganisms. This review aims to provide an overview on the current knowledge about the use of superparamagnetic iron oxide nanoparticles and essential oils on the prevention of microbial adherence and consequent biofilm formation with the goal of being applied on the surface of medical devices. Some limitations found in the studies are discussed.

Human Liver Microsomes Immobilized on Magnetizable Beads: A Novel Approach to Study In Vitro Drug Metabolism

Human liver microsomes (HLM) are a commonly used tool to study drug metabolism in vitro. Typical experiments conducted using suspensions of HLM can be challenging to separate from the incubation solution without lengthy ultracentrifugation steps. Magnetizable beads coated with silica (MGBS) were found to bind strongly to HLM, which could then be isolated and purified using a magnet. Binding of HLM to the MGBS (HLM-MGBS) was demonstrated to be mediated by strong interactions between microsomal phospholipids and MGBS, as artificially prepared phosphatidylcholine (PC) liposomes could be more efficiently captured by the MGBS. HLM-MGBS complexes retained functional cytochrome P450 and uridine-diphosphate-glucuronosyltransferase (UGT) activity as indicated by CYP2C8-mediated amodiaquine de-ethylation, CYP3A4-mediated midazolam 1'hydroxylation, UGT1A1-mediated glucuronidation of estradiol, UGT1A9-mediated glucuronidation of propofol, and UGT2B7-mediated glucuronidation of zidovudine. When comparing suspension HLM alone with HLM-MGBS complexes containing equivalent amounts of HLM, the intrinsic clearance (CLint) of CYP450 substrates was comparable; however, CLint of UGT1A1, UGT1A9, and UGT2B7 was increased in the HLM-MGBS system between 1.5- and 6-fold. HLM-MGBS used in an incubation could also be readily replaced with fresh HLM-MGBS to maintain the presence of active enzymes. Thus, HLM-MGBS demonstrate increased in vitro metabolic efficiency and manipulability, providing a new platform for determination of accurate metabolic parameters. SIGNIFICANCE STATEMENT: The following work describes the strong binding of HLM to magnetizable beads. In addition, the preservation of enzyme activity on the bound HLM provides a novel means to conduct preclinical metabolism studies.

Application of a novel Polydopamine@EDTA@Fe3O4 material for efficient simultaneous nitrogen and nickel removal in an immobilized biofilm reactor

High NO3− and Ni(II) concentrations in mining wastewater pose a risk to public health. In this study, the NO3− and Ni(II) removal process was performed using a novel PDA@EDTA@Fe3O4 immobilization carrier. The effects of hydraulic retention time (HRT; 6, 8, and 10 h), along with Fe(II) (10, 15, and 20 mg/L) and Ni(II) (10, 20, and 30 mg/L) influent concentrations on the simultaneous removal of NO3− and Ni(II) were investigated in immobilized biofilm reactors. Results showed that the highest NO3− removal efficiency (97.78%) and Ni(II) removal efficiency (91.21%) were obtained in the immobilized biofilm reactor with PDA@EDTA@Fe3O4 under the conditions of 10 h HRT, influent Fe(II) concentrations of 20 mg/L and Ni(II) concentrations of 10 mg/L. High-throughput sequencing results confirmed that Cupriavidus sp.CC1 plays a major role in the functioning of the immobilized reactor. This process provides the potential for effective treatment of NO3− and Ni(II) polluted water.

Lipase From Rhizomucor miehei Immobilized on Magnetic Nanoparticles: Performance in Fatty Acid Ethyl Ester (FAEE) Optimized Production by the Taguchi Method

In this communication, it was evaluated the production of fatty acid ethyl ester (FAAE) from the free fatty acids of babassu oil catalyzed by lipase from Rhizomucor miehei (RML) immobilized on magnetic nanoparticles (MNP) coated with 3-aminopropyltriethoxysilane (APTES), Fe₃O₄@APTES-RML or RML-MNP for short. MNPs were prepared by co-precipitation coated with 3-aminopropyltriethoxysilane and used as a support to immobilize RML (immobilization yield: 94.7 ± 1.0%; biocatalyst activity: 341.3 ± 1.2 U_p–NPB/g), which were also activated with glutaraldehyde and then used to immobilize RML (immobilization yield: 91.9 ± 0.2%; biocatalyst activity: 199.6 ± 3.5 U_p–NPB/g). RML-MNP was characterized by X-Ray Powder Diffraction (XRPD), Fourier Transform-Infrared (FTIR) spectroscopy and Scanning Electron Microscope (SEM), proving the incorporation and immobilization of RML on the APTES matrix. In addition, the immobilized biocatalyst presented at 60°C a half-life 16–19 times greater than that of the soluble lipase in the pH range 5–10. RML and RML-MNP showed higher activity at pH 7; the immobilized enzyme was more active than the free enzyme in the pH range (5–10) analyzed. For the production of fatty acid ethyl ester, under optimal conditions [40°C, 6 h, 1:1 (FFAs/alcohol)] determined by the Taguchi method, it was possible to obtain conversion of 81.7 ± 0.7% using 5% of RML-MNP.

Sensitive Readout for Microfluidic High-Throughput Applications using Scanning SQUID Microscopy

Microfluidic chips provide a powerful platform for high-throughput screening of diverse biophysical systems. The most prevalent detection methods are fluorescence based. Developing new readout techniques for microfluidics focusing on quantitative information in the low signal regime is desirable. In this work, we combine the well-established immunoassay approach, with magnetic nanoparticles, with a highly sensitive magnetic imaging technique. We offer to integrate a microfluidic array into a scanning superconducting quantum interference device (SQUID) microscope, to image nanoparticles that were moved through the microfluidic device. We demonstrate the technique on protein-protein interactions (PPI). We compare sensitivity to that of a conventional readout, quantify the amount of interactions, and demonstrate 0.1 atto-mole sensitivity. Our work serves as a proof of concept that will promote the development of a new set of eyes, a stable usable microfluidic-scanning SQUID microscopy.

Continuous manufacturing of silver nanoparticles between 5 and 80 nm with rapid online optical size and shape evaluation

Flexible manufacturing technology of nanoparticles with sizes between 5 and 80 nm. This unique size flexibility is enabled by coupling rapid online spectroscopy and a mathematical Mie theory-based algorithm for size and shape evaluation.

Synthesis, Properties and Applications of Magnetic Nanoparticles and Nanowires—A Brief Introduction

Magnetic nanoparticles and magnetic nano-species of complex topology (e.g., nanorods, nanowires, nanotubes, etc.) are overviewed briefly in the paper, mostly giving attention to the synthetic details and particle composition (e.g., core-shell structures made of different materials). Some aspects related to applications of magnetic nano-species are briefly discussed. While not being a comprehensive review, the paper offers a large collection of references, particularly useful for newcomers in the research area.

Concentration of hepatitis A virus in milk using protamine-coated iron oxide (Fe3O4) magnetic nanoparticles

Hepatitis A virus (HAV) continues to be the leading cause of viral hepatitis. HAV outbreaks have been linked to the consumption of milk, but methods for HAV detection in milk are very limited. We developed a method to concentrate HAV in milk using protamine-coated iron oxide (Fe₃O₄) magnetic nanoparticles (PMNPs). In this study, protamine was covalently coated on the surface of the MNPs (20-30 nm) by a three-step chemical reaction. The successful linkage of protamine to the MNPs was confirmed by Fourier transform infrared spectroscopy (FTIR), zeta potential, and transmission electron microscopy (TEM). When used for concentrating HAV from 40 mL of milk, 50 μL of PMNPs were added to the sample and mixed for 20 min by gentle rotation, followed by a magnet capture for 30 min. The captured PMNPs were washed with glycine buffer (0.05 M glycine, 0.14 M NaCl, 0.2% (v/v) Tween 20, pH 9.0) and HAV RNA was extracted using the QIAamp MinElute Virus Spin Kit and quantified by real-time RT-PCR. The method showed a detection limit of 8.3 × 10⁰ PFU of HAV in milk. The whole concentration procedure could be completed in approximately 50 min. The developed method was simple, inexpensive, and easy-to-perform.

Development of sustainable and reusable silver nanoparticle-coated glass for the treatment of contaminated water

Water contaminants like pathogenic microbes and organic pollutants pose a serious threat to human and aquatic life forms; thus, there is an urgent need to develop a sustainable and affordable water treatment technology. Nanomaterials especially metal nanoparticles have extensive applications in wastewater treatment, but the recovery and aggregation of nanoparticles in solution is a major limitation. In the present work, green synthesized silver nanoparticles were covalently immobilized on a glass surface to prevent aggregation of nanoparticles and to enhance their applicability. Fourier transform infrared (FTIR) of silver nanoparticle (AgNP)-coated glass shows peaks of Si-O-Si, Si-O-C, and Ag-O at 1075 cm^-1, 780 cm^-1, and 608 cm^-1 respectively which confirms the immobilization/conjugation of nanomaterial on glass surface. The surface morphology of immobilized AgNP was studied using scanning electron microscopy (SEM) which reveals nanoparticles are spherical and uniformly distributed on glass surface. The AgNP-coated glass was used for the removal of textile dyes in solution; the result indicates approximately 95% of textile dyes were removed after 5 h of treatment. Removal of microbial contaminants from Yamuna River was studied by optical density analysis and confirmed by fluorescence dye staining. The AgNP-coated glass was also studied for their reusability and the data indicates 50% removal of microbes up to the 5th cycle. To further enhance the applicability, the inhibition of bacterial biofilms were analyzed by dark-field illumination with a fluorescence microscope. Thus AgNP-coated glass can be used in the development of food/water storage containers and in textile industries.

One-step separation of the recombinant protein by using the amine-functionalized magnetic mesoporous silica nanoparticles; an efficient and facile approach

The separation process is the main stage of recombinant production. With the advancement of nanotechnology and the development of magnetic nanoparticles, these structures are increasingly used in different applications. In the present study, we produced the recombinant human growth hormone from Pichia pastoris and for protein separation provided the surfaces similar to chromatographic columns on the surface of magnetic nanoparticles. For this purpose, using a co-precipitation method, the core of Fe₃O₄ was prepared and coated by silica. To increase the protein availability, silica mesoporous formation and its amine functionalization were performed. The specific surface area and the pore size were determined 78.3189 m²/g and 7.44 nm. After the magnetic separation, the sample loading in SDS gel shows a reduction in protein band and the protein absorption at a wavelength of 280 nm. Finally, we evaluate the ability of amine functionalized nanoparticles for protein separation that demonstrate the adsorption capacity significantly increased compare with silica-coated nanoparticles. The amine functionalized nanoparticles provide the maximum adsorption capacity of 235.21 μg/mg and after the elution, protein concentration determined 476 mg/L. This work indicates the functionalized magnetic mesoporous silica nanoparticles can be used as the best candidate for the separation of different biological macromolecules.

Suitability of Recombinant Lipase Immobilised on Functionalised Magnetic Nanoparticles for Fish Oil Hydrolysis

Recombinant Bacillus subtilis lipase was immobilised on magnetic nanoparticles by a facile covalent method and applied to fish oil hydrolysis. High loading of enzyme to the functionalised nanoparticle was achieved with a protein binding efficiency of 95%. Structural changes of the confined enzyme on the surface of the nanoparticles was investigated using transmission electron microscopy and spectroscopic techniques (attenuated total reflectance-Fourier transform infrared and circular dichroism). The biocatalytic potential of immobilised lipase was compared with that of free enzyme and biochemically characterised with respect to different parameters such as pH, temperature, substrate concentrations and substrate specificity. The thermal stability of functionalised nanoparticle bound enzyme was doubled that of free enzyme. Immobilised lipase retained more than 50% of its initial biocatalytic activity after recyclability for twenty cycles. The ability to the immobilised thermostable lipase to concentrate omega-3 fatty acids from fish oil was investigated. Using synthetic substrate, the immobilised enzyme showed 1.5 times higher selectivity for docosahexaenoic acid (DHA), and retained the same degree of selectivity for eicosapentaenoic acid (EPA), when compared to the free enzyme.