Food related applications of magnetic iron oxide nanoparticles: Enzyme immobilization, protein purification, and food analysis

Advancements in enzyme immobilization on magnetic nanomaterials: toward sustainable industrial applications

Enzymes are widely used in biofuels, food, and pharmaceuticals. The immobilization of enzymes on solid supports, particularly magnetic nanomaterials, enhances their stability and catalytic activity. Magnetic nanomaterials are chosen for their versatility, large surface area, and superparamagnetic properties, which allow for easy separation and reuse in industrial processes. Researchers focus on the synthesis of appropriate nanomaterials tailored for specific purposes. Immobilization protocols are predefined and adapted to both enzymes and support requirements for optimal efficiency. This review provides a detailed exploration of the application of magnetic nanomaterials in enzyme immobilization protocols. It covers methods, challenges, advantages, and future perspectives, starting with general aspects of magnetic nanomaterials, their synthesis, and applications as matrices for solid enzyme stabilization. The discussion then delves into existing enzymatic immobilization methods on magnetic nanomaterials, highlighting advantages, challenges, and potential applications. Further sections explore the industrial use of various enzymes immobilized on these materials, the development of enzyme-based bioreactors, and prospects for these biocatalysts. In summary, this review provides a concise comparison of the use of magnetic nanomaterials for enzyme stabilization, highlighting potential industrial applications and contributing to manufacturing optimization.

Break oily water emulsion during petroleum enhancing production processes using green approach for the synthesis of SnCuO@FeO nanocomposite from microorganisms

The aim of this work was to synthesize a green nanoparticle SnCuO@FeO nanocomposite core-shell to break oily water emulsions during petroleum-enhancing production processes as an alternative to chemical and physical processes. In this study, eight bacterial isolates (MHB1-MHB8) have been isolated from tree leaves, giant reeds, and soil samples. The investigation involved testing bacterial isolates for their ability to make FeO nanoparticles and choosing the best producers. The selected isolate (MHB5) was identified by amplification and sequencing of the 16S rRNA gene as Bacillus paramycoides strain OQ878685. MHB5 produced the FeO nanoparticles with the smallest particle size (78.7 nm) using DLS. XRD, FTIR, and TEM were used to characterize the biosynthesized nanoparticles. The jar experiment used SnCuO@FeO with different ratios of Sn to CuO (1:1, 2:1, and 3:1) to study the effect of oil concentration, retention time, and temperature. The most effective performance was observed with a 1:1 ratio of Sn to CuO, achieving an 85% separation efficiency at a concentration of 5 mg/L, for a duration of 5 min, and at a temperature of 373 K. Analysis using kinetic models indicates that the adsorption process can be accurately described by both the pseudo-first-order and pseudo-second-order models. This suggests that the adsorption mechanism likely involves a combination of film diffusion and intraparticle diffusion. Regarding the adsorption isotherm, the Langmuir model provides a strong fit for the data, while the D-R model indicates that physical interactions primarily govern the adsorption mechanism. Thermodynamic analysis reveals a ∆H value of 18.62 kJ/mol, indicating an exothermic adsorption process. This suggests that the adsorption is a favorable process, as energy is released during the process. Finally, the synthesized green SnCuO@FeO nanocomposite has potential for use in advanced applications in the oil and gas industry to help the industry meet regulatory compliance, lower operation costs, reduce environmental impact, and enhance production efficiency.

Carboxyethylsilanetriol-Coated Magnetic Nanoparticles as an Ultrasensitive Immunoplatform for Electrochemical Magnetosensing of Cotinine

In the present study, an innovative and simple electrochemical magneto biosensor based on carboxyethylsilanetriol-modified iron oxide (Fe3O4) magnetic nanoparticles was designed for ultrasensitive and specific analysis of cotinine, an important marker of smoking. Anticotinine antibodies were covalently immobilized on carboxylic acid-modified magnetic nanoparticles, and the cotinine-specific magnetic nanoparticles created a specific surface on the working electrode surface. The use of magnetic nanoparticles as an immobilization platform for antibodies provided a large surface area for antibody attachment and increased sensitivity. In addition, the advantages of the new immobilization platform were reusing the working electrode numerous times, recording repeatable and reproducible signals, and reducing the necessary volume of biomolecules. The specific interaction between cotinine and cotinine-specific antibody-attached magnetic nanoparticles restricted the electron transfer of the redox probe and changed the impedimetric response of the electrode correlated to the concentration of cotinine. The magneto biosensor had a wide detection range (2-300 pg/mL), a low LOD (606 fg/mL), and an acceptable recovery (97.24-105.31%) in real samples. In addition, the current biosensor's measurement results were in good agreement with those found by the standard liquid chromatography (HPLC) and enzyme-linked immunosorbent assay (ELISA) methods. These results showed that a simple impedimetric immunosensing platform was generated for the cotinine analysis.

A poly(o-phenylenediamine) coated aluminum garter spring micro-solid phase extractor for pyrethroids in chili

An aluminum garter spring coated with poly(o-phenylenediamine) (PoPD) was developed as a sorbent for the micro-solid phase extraction of seven pyrethroids, bifenthrin, fenpropathrin, lambda-cyhalothrin, cyfluthrin, permethrin, cypermethrin and deltamethrin from fresh chili, chili flakes, and curry pastes. The extraction was qualified and quantified by a gas chromatograph coupled with an electron capture detector. Under optimum conditions, the linearity was at a concentration range of 10-3000 µg kg-1. The limits of detection and limits of quantitation of 9.3 to 34.2 μg kg-1, and 11.8 to 48.6 μg kg-1, respectively, were obtained with good sorbent-to-sorbent reproducibility, and outstanding reusability. When applied to determine the seven pyrethroids in chili samples, some pyrethroids were detected up to 30.3 ± 1.2 μg kg-1. This proposed method is simple, with potential applications in the trace analysis of other compounds.

Selection of DNA aptamers for the aptamer-assisted magnetic capture of the purified xylanase from Aspergillus niger

Xylanases are a group of enzymes that catalyze the hydrolysis of xylan. Xylanases have wide industrial applications, and they can produced by various organisms. In this study, we aimed to develop aptamers for the capture of xylanase produced by a wild-type Aspergillus niger strain. Xylanase was produced by Aspergillus niger in a 5-liter stirred-tank bioreactor and then purified by column chromatography. Magnetic bead-based SELEX (Systematic Evolution of Ligands by Exponential Enrichment) was performed to select DNA aptamers specific to the purified xylanase. After nine rounds of selection, next-generation sequencing (NGS) analysis was performed. Four aptamers, namely AXYL-1, AXYL-2, AXYL-3, and AXYL-4, were identified for further characterization. The binding properties of the selected aptamers were characterized by fluorescence quenching (FQ) analysis and an enzyme-linked aptamer assay (ELAA). The Kd values were found to be in the low μM range. Then, each aptamer was immobilized on streptavidin-coated magnetic particles, and the recovery ratio of xylanase was determined. Although AXYL-1 wasn't effective, AXYL-2, AXYL-3, and AXYL-4 were proven to capture the xylanase. The maximum recovery rate of xylanase was found to be approximately 54 %.

Magnetic hydrogel applications in articular cartilage tissue engineering

Articular cartilage defects afflict millions of individuals worldwide, presenting a significant challenge due to the tissue's limited self-repair capability and anisotropic nature. Hydrogel-based biomaterials have emerged as promising candidates for scaffold production in artificial cartilage construction, owing to their water-rich composition, biocompatibility, and tunable properties. Nevertheless, conventional hydrogels typically lack the anisotropic structure inherent to natural cartilage, impeding their clinical and preclinical applications. Recent advancements in tissue engineering (TE) have introduced magnetically responsive hydrogels, a type of intelligent hydrogel that can be remotely controlled using an external magnetic field. These innovative materials offer a means to create the desired anisotropic architecture required for successful cartilage TE. In this review, we first explore conventional techniques employed for cartilage repair and subsequently delve into recent breakthroughs in the application and utilization of magnetic hydrogels across various aspects of articular cartilage TE.

Recent advances on the preparation conditions, structural characteristics, physicochemical properties, functional properties and potential applications of dialdehyde starch: A review

Starch, a natural storage polysaccharide of plant kingdom, has many industrial applications. However, native starch has some inherent shortages, which can be overcome by structural modification. Dialdehyde starch, one kind of oxidized starch produced by periodate oxidation, has good physical properties and bioactivities with wide applications in different fields. Dialdehyde starch is typically achieved by oxidizing native starch slurry through periodate oxidation under controlled reaction conditions. Several factors including the source of starch, the type of oxidant, the molar ratio of oxidant to starch, reaction temperature, reaction time and solution pH value can influence the synthesis of dialdehyde starch. Dialdehyde starch shows different spectroscopic/chromatographic characters and physicochemical properties from native starch. Moreover, dialdehyde starch exhibits good antioxidant activity, antimicrobial activity and cross-linking property. Based on these functional properties, dialdehyde starch has shown application potentials in food packaging, thermoplastic production, enzyme immobilization, heavy metal ion adsorption, drug delivery, wood adhesion and leather tanning. In this review, the preparation conditions, structural characteristics, physicochemical properties, functional properties and potential applications of dialdehyde starch are summarized for the first time. The future research and development prospects of dialdehyde starch are also discussed.

Green synthesis of iron nanoparticles: Sources and multifarious biotechnological applications

Green synthesis of iron nanoparticles is a highly fascinating research area and has gained importance due to reliable, sustainable and ecofriendly protocol for synthesizing nanoparticles, along with the easy availability of plant materials and their pharmacological significance. As an alternate to physical and chemical synthesis, the biological materials, like microorganisms and plants are considered to be less costly and environment-friendly. Iron nanoparticles with diverse morphology and size have been synthesized using biological extracts. Microbial (bacteria, fungi, algae etc.) and plant extracts have been employed in green synthesis of iron nanoparticles due to the presence of various metabolites and biomolecules. Physical and biochemical properties of biologically synthesized iron nanoparticles are superior to that are synthesized using physical and chemical agents. Iron nanoparticles have magnetic property with thermal and electrical conductivity. Iron nanoparticles below a certain size (generally 10-20 nm), can exhibit a unique form of magnetism called superparamagnetism. They are non-toxic and highly dispersible with targeted delivery, which are suitable for efficient drug delivery to the target. Green synthesized iron nanoparticles have been explored for multifarious biotechnological applications. These iron nanoparticles exhibited antimicrobial and anticancerous properties. Iron nanoparticles adversely affect the cell viability, division and metabolic activity. Iron nanoparticles have been used in the purification and immobilization of various enzymes/proteins. Iron nanoparticles have shown potential in bioremediation of various organic and inorganic pollutants. This review describes various biological sources used in the green synthesis of iron nanoparticles and their potential applications in biotechnology, diagnostics and mitigation of environmental pollutants.

Nanoparticles-assisted aptamer biosensing for the detection of environmental pathogens

Given the importance of public health, it is crucial to develop quick, targeted, highly sensitive, and accurate technologies to monitor pathogenic microbes in response to the growing concerns of food and environmental safety. Although conventional approaches for microbiological detection are available, they are laborious, and often skill demanding. Therefore, such approaches are incompetent in the on-site or high-throughput assessment of pathogenic microbes. Numerous efforts have been made to develop biosensors that use nucleic acid aptamer as the biorecognition element, which would avoid the abovementioned limitations. Incorporating nanomaterials (NMs) into aptamer-based biosensors (aptasensors) improves their sensitivity and specificity, opening exciting possibilities for various applications, such as bioanalysis of food and environmental samples. Over the last decade, nanomaterial-conjugated aptasensors have seen a steadily rising demand. To this end, the main goal of this study is to demonstrate the novelty in the design of nanomaterial-conjugated aptasensors and how they can be used to detect different pathogenic microbes in water and food. The intent of this paper is to evaluate the cutting-edge techniques that have appeared in nano-aptasensors throughout the past few years, such as manufacturing procedures, analytical credibility, and sensing mechanisms. Additionally, the fundamental performance parameters of aptasensing techniques (such as detection limits, and sensing ranges response) were also used to evaluate their practical applicability. Finally, it is anticipated that this study will inspire innovative ideas and techniques for the construction and use of aptasensors for monitoring pathogenic microorganisms in food, drinks, recreational water, and wastewater.

In-vivo anticoccidial efficacy of green synthesized iron-oxide nanoparticles using Ficus racemosa Linn leaf extract. (Moraceae) against Emeria tenella infection in broiler chicks

Coccidiosis is an acute gastrointestinal parasitic disease and causes approximately $2.80 to $3.27 per m2 loss in a broiler farm of a 33-day-old flock. In this study, iron oxide nanoparticles (IONPs) were green synthesized using the aqueous leaf extract of Ficus racemosa as a reducing and capping agent to reduce the emerging resistance in coccidia spores against conventional treatments and boost the immune level in broilers. These IONPs were evaluated for their impacts on the growth performance, biochemistry, blood profile, and histology in the coccidiodized broiler chicken with Emeria tenella under in vivo conditions. The characteristics and stability of particles were obtained using UV-Vis spectroscopy, Fourier transforms infrared (FTIR), X-Ray diffraction (XRD), energy dispersive X-ray absorption (EDX), scanning electron microscopy (SEM), zeta potential and zeta size. The results indicated that IONPs at the moderate dose of 15 mg/kg (p = 0.001) reduced the coccidial impacts by eliminating oocyst shedding per gram feces (up to 91%) and reducing clinical symptoms (lesions (LS = 0), bloody diarrhea (No), and mortality (0%) in chicken at day 10 of treatment as compared to the negative control group-B (infected & non-treated). A dose-dependent and time-dependent trend were observed during treatments (10, 15, and 20 mg/kg) of 1-3 weeks using IONPs against the coccidial impacts on the growth parameters (body weight gain, mean feed consumption, feed conversion ratio) and biochemistry (plasma glucose, total protein, uric acid, ALT, AST, and ALP) in chickens. Additionally, F. racemosa IONPs at a dose of 15 and 20 mg/kg significantly recovered the parasitized and highly damaged hepatocytes, liver tissues, and ceca tissues after 1-3 weeks of treatment in broiler chickens. Overall, the 15 mg/kg concentration of IONPs exhibited fast recovery and growth enhancement in coccidiodized broilers. Therefore, the 15 mg/kg dose of green synthesized IONPs using leaf extract of F. racemosa could be a potential and safe anticoccidial agent with targeted implications in the poultry industry.

Microperoxidase-11 functionalized nanozyme with enhanced peroxidase-mimicking activities for visual detection of cysteine

Various nanomaterials with peroxidase activity (nanozyme) have been designed for bio catalysis and biosensing, however, most of them need further design and modification of probe molecules for the specific binding reaction with targets. This results in a decrease in catalysis activity and hinders them to be perfect alternatives to natural enzyme in biosensing. In this work, an enhanced nanozyme was synthesized by functionalizing natural microperoxidase-11 (MP-11) on a hybrid graphene oxide-gold (GO-Au) material. The designed nanozyme showed an enhanced catalysis activity and realized a robust and efficient colorimetric detection of cysteine based on specific binding reaction between active iron center from MP-11 and thiol in cysteine. The enhanced properties show promising applications of complex nanozyme and provides a great opportunity for developing efficient sensing systems.

Biocompatible green technology principles for the fabrication of food packaging material with noteworthy mechanical and antimicrobial properties A sustainable developmental goal towards the effective, safe food preservation strategy

Biocompatible, eco-friendly, highly economical packaging methods should be needed as conventional packaging is known to cause undesirable effects. As food packaging is the major determining factor of food safety, the selection or methods of packaging materials plays a pioneering role. With this scope, modern food technology seeks unique sustainable approaches for the fabrication of package materials with notable desired properties. The principles, features, and fabrication methodology of modern food packaging are briefly covered in this review. We extensively revealed improved packaging (nanocoating, nanolaminates, and nano clay), active packaging (antimicrobial, oxygen scavenging, and UV barrier packaging), and intelligent/smart packaging (O2 indicator, CO2 indicator, Time Temperature Indicator, freshness indicator, and pH indicator). In particular, we described the role of nanomaterials in the fabrication of packaging material. Methods for the evaluation of mechanical, barrier properties, and anti-microbial assays have been featured. The present studies suggest the possible utilization of materials in the fabrication of food packaging for the production, utilization, and distribution of safe foods without affecting nutritional values.

Immobilized short-chain dehydrogenase/reductase on Fe3O4 particles acts as a magnetically recoverable biocatalyst component in patulin bio-detoxification system

Patulin is one of the most important mycotoxins that contaminates fruit-derived products and causes acute or chronic toxicity in humans. In the present study, a novel patulin-degrading enzyme preparation was developed by taking a short-chain dehydrogenase/reductase and covalently linking it to dopamine/polyethyleneimine co-deposited magnetic Fe₃O₄ particles. Optimum immobilization provided 63% immobilization efficiency and 62% activity recovery. Moreover, the immobilization protocol substantially improved thermal and storage stabilities, proteolysis resistance, and reusability. Using reduced nicotinamide adenine dinucleotide phosphate as a cofactor, the immobilized enzyme exhibited a detoxification rate of 100% in phosphate-buffered saline and a detoxification rate of more than 80% in apple juice. The immobilized enzyme did not cause adverse effects on juice quality and could be magnetically separated quickly after detoxification to ensure convenient recycling. Moreover, it did not exhibit cytotoxicity against a human gastric mucosal epithelial cell line at a concentration of 100 mg/L. Consequently, the immobilized enzyme as a biocatalyst had the characteristics of high efficiency, stability, safety, and easy separation, establishing the first step in building a bio-detoxification system to control patulin contamination in juice and beverage products.

Application of Iron Nanoparticle-Based Materials in the Food Industry

Due to their different properties compared to other materials, nanoparticles of iron and iron oxides are increasingly used in the food industry. Food technologists have especially paid attention to their ease of separation by magnetic fields and biocompatibility. Unfortunately, the consumption of increasing amounts of nanoparticles has raised concerns about their biotoxicity. Hence, knowledge about the applicability of iron nanoparticle-based materials in the food industry is needed not only among scientists, but also among all individuals who are involved in food production. The first part of this article describes typical methods of obtaining iron nanoparticles using chemical synthesis and so-called green chemistry. The second part of this article describes the use of iron nanoparticles and iron nanoparticle-based materials for active packaging, including the ability to eliminate oxygen and antimicrobial activity. Then, the possibilities of using the magnetic properties of iron nano-oxides for enzyme immobilization, food analysis, protein purification and mycotoxin and histamine removal from food are described. Other described applications of materials based on iron nanoparticles are the production of artificial enzymes, process control, food fortification and preserving food in a supercooled state. The third part of the article analyzes the biocompatibility of iron nanoparticles, their impact on the human body and the safety of their use.

Biocatalysis as a Green Approach for Synthesis of Iron Nanoparticles—Batch and Microflow Process Comparison

There is a growing need for production of iron particles due to their possible use in numerous systems (e.g., electrical, magnetic, catalytic, biological and others). Although severe reaction conditions and heavy solvents are frequently used in production of nanoparticles, green synthesis has arisen as an eco-friendly method that uses biological catalysts. Various precursors are combined with biological material (such as enzymes, herbal extracts, biomass, bacteria or yeasts) that contain chemicals from the main or secondary metabolism that can function as catalysts for production of nanoparticles. In this work, batch (“one-pot”) biosynthesis of iron nanoparticles is reviewed, as well as the possibilities of using microfluidic systems for continuous biosynthesis of iron nanoparticles, which could overcome the limitations of batch synthesis.

Design and Development of Magnetic Iron Core Gold Nanoparticle-Based Fluorescent Multiplex Assay to Detect Salmonella

Salmonella is a bacterial pathogen which is one of the leading causes of severe illnesses in humans. The current study involved the design and development of two methods, respectively using iron oxide nanoparticle (IONP) and iron core gold nanoparticle (ICGNP), conjugated with the Salmonella antibody and the fluorophore, 4-Methylumbelliferyl Caprylate (4-MUCAP), used as an indicator, for its selective and sensitive detection in contaminated food products. Twenty double-blind beverage samples, spiked with Salmonella enteritidis, Staphylococcus aureus, and Escherichia coli, were prepared in sterile Eppendorf^® tubes at room temperature. The gold layer and spikes of ICGNPs increased the surface areas. The ratio of the surface area is 0.76 (IONPs/ICGNPs). The comparative sensitivity and specificity of the IONP-based and the ICGNP-based methods to detect Salmonella were determined. The ICGNP method shows the limit of detection is 32 Salmonella per mL. The ICGNPs had an 83.3% sensitivity and a 92.9% specificity value for the presence and detection of Salmonella. The IONP method resulted in a limit of detection of 150 Salmonella per mL, and a 66.7% sensitivity and 83.3% specificity for the presence and detection of Salmonella. The higher surface area of ICGNPs increases the efficiency of detection. The monitoring of Salmonella can thus be achieved by a rapid magnetic fluorescent assay using a smartphone for image capture and analyze, providing quantitative results. The findings from the present study would help to detect Salmonella rapidly in water. It can improve the microbial quality of water and food safety due to the presence of Salmonella in the water environment.

Characterization of Carboxylic Acid Reductase from Mycobacterium phlei Immobilized onto Seplite LX120

A multi-domain oxidoreductase, carboxylic acid reductase (CAR), can catalyze the one-step reduction of carboxylic acid to aldehyde. This study aimed to immobilize bacterial CAR from a moderate thermophile Mycobacterium phlei (MpCAR). It was the first work reported on immobilizing bacterial CAR onto a polymeric support, Seplite LX120, via simple adsorption. Immobilization time and protein load were optimized for MpCAR immobilization. The immobilized MpCAR showed optimal activity at 60 °C and pH 9. It was stable over a wide range of temperatures (10 to 100 °C) and pHs (4–11), retaining more than 50% of its activity. The immobilized MpCAR also showed stability in polar solvents. The adsorption of MpCAR onto the support was confirmed by Scanning Electron Microscopy (SEM), Fourier-Transform Infrared (FTIR) spectroscopy, and Brunauer–Emmett–Teller (BET) analysis. The immobilized MpCAR could be stored for up to 6 weeks at 4 °C and 3 weeks at 25 °C. Immobilized MpCAR showed great operational stability, as 59.68% of its activity was preserved after 10 assay cycles. The immobilized MpCAR could also convert approximately 2.6 mM of benzoic acid to benzaldehyde at 60 °C. The successfully immobilized MpCAR on Seplite LX120 exhibited improved properties that benefit green industrial processes.

Assessment of the potential toxic effect of magnetite nanoparticles on the male reproductive system based on immunological and molecular studies

Magnetite nanoparticles (MNPs) are the most conventional type of iron oxide nanoparticles used in the food industrial processes, removal of heavy metals, and biomedical applications in vivo or in vitro. Until now, there is no sufficient information that can confirm its effect on the body's immune system and reproductive health in males. The purpose of this research is to estimate the immunotoxic and reproductive toxic effects of MNPs in male rats. This study included 36 adult male albino rats divided into three groups. The experimental groups were intraperitoneally injected with MNPs at doses of 5 and 10 mg/kg body weight 3 times/week for 60 days, while the control group was injected with saline solution. MNPs caused a significant decrease in the body weight change of the high-treated group. MNPs produced changes in the lymphocyte proliferation rate which referred to a significant immunotoxic effect measured by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-di-phenyltetrazolium bromide reduction method. The testicular tissue of male-treated rats showed some moderate and severe degenerative changes. The sperm parameters of count, motility, and viability were significantly decreased. Sperm morphological abnormalities were detected in all treated animals. MNPs produced a significant decrease in testosterone levels, increased the level of malondialdehyde, impaired the activity of the antioxidant enzymes and induced testicular DNA damage. In conclusion, MNPs affected the normal immune state in male rats and facilitated the generation of reactive oxygen species subsequently triggering testicular oxidative stress damages. All these consequences had a negative impact on male reproductive health.

A review on recent advances in the applications of composite Fe3O4 magnetic nanoparticles in the food industry

Fe3O4 magnetic nanoparticles (MNPs) have attracted tremendous attention due to their superparamagnetic properties, large specific surface area, high biocompatibility, non-toxicity, large-scale production, and recyclability. More importantly, numerous hydroxyl groups (-OH) on the surface of Fe3O4 MNPs can provide coupling sites for various modifiers, forming versatile nanocomposites for applications in the energy, biomedicine, and environmental fields. With the development of science and technology, the potential of nanotechnology in the food industry has also gradually become prominent. However, the application of composite Fe3O4 MNPs in the food industry has not been systematically summarized. Herein, this article reviews composite Fe3O4 MNPs, including their properties, modifications, and physical functions, as well as their applications in the entire food industry from production to processing, storage, and detection. This review lays a solid foundation for promoting food innovation and improving food quality and safety.

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.

Immobilization of fibrinolytic protease from Mucor subtilissimus UCP 1262 in magnetic nanoparticles

This work reports the immobilization of a fibrinolytic protease (FP) from Mucor subtilissimus UCP 1262 on Fe₃O₄ magnetic nanoparticles (MNPs) produced by precipitation of FeCl₃·6H₂O and FeCl₂·4H₂O, coated with polyaniline and activated with glutaraldehyde. The FP was obtained by solid state fermentation, precipitated with 40-60% ammonium sulfate, and purified by DEAE-Sephadex A50 ion exchange chromatography. The FP immobilization procedure allowed for an enzyme retention of 52.13%. The fibrinolytic protease immobilized on magnetic nanoparticles (MNPs/FP) maintained more than 60% of activity at a temperature of 40 to 60 °C and at pH 7 to 10, when compared to the non-immobilized enzyme. MNPs and MNPs/FP did not show any cytotoxicity against HEK-293 and J774A.1 cells. MNPs/FP was not hemolytic and reduced the hemolysis induced by MNPs from 2.07% to 1.37%. Thrombus degradation by MNPs/FP demonstrated that the immobilization process guaranteed the thrombolytic activity of the enzyme. MNPs/FP showed a total degradation of the γ chain of human fibrinogen within 90 min. These results suggest that MNPs/FP may be used as an alternative strategy to treat cardiovascular diseases with a targeted release through an external magnetic field.

Immobilization of papain: A review

Papain is a cysteine protease from papaya, with many applications due to its broad specificity. This paper reviews for first time the immobilization of papain on different supports (organic, inorganic or hybrid supports) presenting some of the features of the utilized immobilization strategies (e.g., epoxide, glutaraldehyde, genipin, glyoxyl for covalent immobilization). Special focus is placed on the preparation of magnetic biocatalysts, which will permit the simple recovery of the biocatalyst even if the medium is a suspension. Problems specific to the immobilization of proteases (e.g., steric problems when hydrolyzing large proteins) are also defined. The benefits of a proper immobilization (enzyme stabilization, widening of the operation window) are discussed, together with some artifacts that may suggest an enzyme stabilization that may be unrelated to enzyme rigidification.

The untapped potential of magnetic nanoparticles for forensic investigations: A comprehensive review

With a growing interest in precise and sensitive diagnosis for criminal investigations, nanoparticles (NPs) have intrigued scientific minds working in the field of forensic science due to their exceptional properties. Magnetic nanoparticles (MNPs) have emerged as a powerful tool for improving forensic analysis due to their super magnetic behavior combined with smaller dimensions. MNP-based applications can benefit criminologists to solve criminal mysteries with greater precision and pace. This review highlights the different types of MNP-based applications and their developmental and implicational aspects of forensic science. It also renders insight into the future prospects of a splendid blend of nanotechnology and forensic science, leading to a better scientific analysis.

Development of a High-Efficiency Immunomagnetic Enrichment Method for Detection of Human Norovirus via PAMAM Dendrimer/SA-Biotin Mediated Cascade-Amplification

Human norovirus is a common cause of acute gastroenteritis worldwide, and oysters have been found to be the main carriers for its spread. The lack of efficient pre-treatment methods has been a major bottleneck limiting the detection of viruses in oysters. In this study, we established a novel immunomagnetic enrichment method using polyamidoamine (PAMAM) dendrimer/SA-biotin-mediated cascade amplification for reverse transcriptase quantitative real-time polymerase chain reaction (RT-qPCR) detection. We compared the capture efficiency of traditional immunomagnetic enrichment, biotin-amplified immunomagnetic enrichment, and PAMAM dendrimer/SA-biotin-mediated cascade-amplification immunomagnetic enrichment. The optimal capture efficiency of the novel method was 44.26 ± 1.45%, which increased by 183.17% (P < 0.01) and 18.09% (P < 0.05) compared with the first two methods, respectively. Three methods were all applied in detecting norovirus in 44 retail oysters, the detection rate of the PAMAM dendrimer/SA-biotin-mediated method was 25.0%, which was higher than those of traditional IME (15.90%) and SA-biotin-amplified IME (18.80%) by 9.1 and 6.2%, respectively. In conclusion, the novel method can be applied for the rapid detection of norovirus in oysters, which can help reduce the cost and time of detection and improve detection rates.

Current Applications of Magnetic Nanomaterials for Extraction of Mycotoxins, Pesticides, and Pharmaceuticals in Food Commodities

Environmental pollutants, such as mycotoxins, pesticides, and pharmaceuticals, are a group of contaminates that occur naturally, while others are produced from anthropogenic sources. With increased research on the adverse ecological and human health effects of these pollutants, there is an increasing need to regularly monitor their levels in food and the environment in order to ensure food safety and public health. The application of magnetic nanomaterials in the analyses of these pollutants could be promising and offers numerous advantages relative to conventional techniques. Due to their ability for the selective adsorption, and ease of separation as a result of magnetic susceptibility, surface modification, stability, cost-effectiveness, availability, and biodegradability, these unique magnetic nanomaterials exhibit great achievement in the improvement of the extraction of different analytes in food. On the other hand, conventional methods involve longer extraction procedures and utilize large quantities of environmentally unfriendly organic solvents. This review centers its attention on current applications of magnetic nanomaterials and their modifications in the extraction of pollutants in food commodities.

Bio-nano interactions: binding proteins, polysaccharides, lipids and nucleic acids onto magnetic nanoparticles

The major interest in nanoparticles as an application platform for biotechnology arises from their high surface-to-volume ratio. Iron oxide nanoparticles (IONPs) are particularly appealing due to their superparamagnetic behavior, which enables bioseparation using external magnetic fields. In order to design advanced biomaterials, improve binding capacities and develop innovative processing solutions, a thorough understanding of the factors governing organic-inorganic binding in solution is critical but has not yet been achieved, given the wide variety of chemical and physical influences. This paper offers a critical review of experimental studies of the interactions between low cost IONPs (bare iron oxides, silica-coated or easily-functionalized surfaces) and the main groups of biomolecules: proteins, lipids, nucleic acids and carbohydrates. Special attention is devoted to the driving forces and interdependencies responsible of interactions at the solid-liquid interface, to the unique structural characteristics of each biomolecular class, and to environmental conditions influencing adsorption. Furthermore, studies focusing on mixtures, which are still rare, but absolutely necessary to understand the biocorona, are also included. This review concludes with a discussion of future work needed to fill the gaps in knowledge of bio-nano interactions, seeking to improve nanoparticles' targeting capabilities in complex systems, and to open the door for multipurpose recognition and bioseparation processes.

Nanoparticles in the Food Industry and Their Impact on Human Gut Microbiome and Diseases

The use of inorganic nanoparticles (NPs) has expanded into various industries including food manufacturing, agriculture, cosmetics, and construction. This has allowed NPs access to the human gastrointestinal tract, yet little is known about how they may impact human health. As the gut microbiome continues to be increasingly implicated in various diseases of unknown etiology, researchers have begun studying the potentially toxic effects of these NPs on the gut microbiome. Unfortunately, conflicting results have limited researcher’s ability to evaluate the true impact of NPs on the gut microbiome in relation to health. This review focuses on the impact of five inorganic NPs (silver, iron oxide, zinc oxide, titanium dioxide, and silicon dioxide) on the gut microbiome and gastrointestinal tract with consideration for various methodological differences within the literature. This is important as NP-induced changes to the gut could lead to various gut-related diseases. These include irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), celiac disease, and colorectal cancer. Research in this area is necessary as the use of NPs in various industries continues to grow along with the number of people suffering from chronic gastrointestinal diseases.

Magnetic micro-macro biocatalysts applied to industrial bioprocesses

The use of magnetic biocatalysts is highly beneficial in bioprocesses technology, as it allows their easy recovering and enhances biocatalyst lifetime. Thus, it simplifies operational processing and increases efficiency, leading to more cost-effective processes. The use of small-size matrices as carriers for enzyme immobilization enables to maximize surface area and catalysts loading, also reducing diffusion limitations. As highly expensive nanoparticles (nm size) usually aggregate, their application at large scale is not recommended. In contrast, the use of magnetic micro-macro (µm-mm size) matrices leads to more homogeneous biocatalysts with null or very low aggregation, which facilitates an easy handling and recovery. The present review aims to highlight recent trends in the application of medium-to-high size magnetic biocatalysts in different areas (biodiesel production, food and pharma industries, protein purification or removal of environmental contaminants). The advantages and disadvantages of these above-mentioned magnetic biocatalysts in bioprocess technology will be also discussed.

Green synthesis of iron-based nanoparticles using Chlorophytum comosum leaf extract: methyl orange dye degradation and antimicrobial properties

Nowadays, green synthesis methods have gained growing attention in nanotechnology owning to their versatile features including high efficiency, cost-effectiveness, and eco-friendliness. Here, the aqueous extract of Chlorophytum comosum leaf was applied for the preparation of iron nanoparticles (INPs) to obtain spherical and amorphous INPs with a particle size below 100 nm as confirmed by TEM. The synthesized INPs managed to eliminate methyl orange (MO) from the aqueous solution. The concentration of MO can be easily checked via ultraviolet-visible (UV-Vis) spectroscopy throughout the usage of INPs at the presence of H2O2. The synthesized INPs exhibited MO degradation efficiency of 77% after 6 h. Furthermore, the synthesized INPs exhibited antibacterial activity against both Gram-negative and Gram-positive bacteria. The prepared INPs have an impressive effect on Staphylococcus aureus at concentrations below 6 μg/ml. Overall, the synthesized INPs could considerably contribute to our combat against organic dyes and bacteria.

Inactivation of Bacteria Using Bioactive Nanoparticles and Alternating Magnetic Fields

Foodborne pathogens are frequently associated with risks and outbreaks of many diseases; therefore, food safety and processing remain a priority to control and minimize these risks. In this work, nisin-loaded magnetic nanoparticles were used and activated by alternating 10 and 125 mT (peak to peak) magnetic fields (AMFs) for biocontrol of bacteria Listeria innocua, a suitable model to study the inactivation of common foodborne pathogen L. monocytogenes. It was shown that L. innocua features high resistance to nisin-based bioactive nanoparticles, however, application of AMFs (15 and 30 min exposure) significantly potentiates the treatment resulting in considerable log reduction of viable cells. The morphological changes and the resulting cellular damage, which was induced by the synergistic treatment, was confirmed using scanning electron microscopy. The thermal effects were also estimated in the study. The results are useful for the development of new methods for treatment of the drug-resistant foodborne pathogens to minimize the risks of invasive infections. The proposed methodology is a contactless alternative to the currently established pulsed-electric field-based treatment in food processing.

Risk assessment of iron oxide nanoparticles in an aquatic ecosystem: A case study on Biomphalaria glabrata

Iron oxide nanoparticles (IONPs) have been applied in several sectors in the environmental field, such as aquatic nanoremediation, due to their unique superparamagnetic and nanospecific properties. However, the knowledge of chronic toxicity of IONPs on aquatic invertebrate remains limited. Thus, the present study aimed to analyze the chronic toxicity of gluconic acid-functionalized IONPs (GLA-IONPs) and their dissolved counterpart (FeCl₃) to freshwater snail Biomphalaria glabrata. GLA-IONPs were synthesized and characterized by multiple techniques, and the snails were exposed to both Fe forms at environmentally relevant concentrations (1.0-15.6 mg L^-1) for 28 days. The bioaccumulation, mortality rate, behavior impairments, morphological alterations, fecundity and fertility of snails were analyzed. Results showed that GLA-IONPs induced high iron bioaccumulation in the entire soft tissue portion. Chronic exposure to GLA-IONP increased the behavioral impairments of snails compared to iron ions and control groups. Both Fe forms reduced the fecundity, while the mortality and reduced fertility were observed only after the exposure to GLA-IONPs at 15.6 mg L^-1. Overall results indicated the behavioral impairments and reproductive toxicity associated, possibly, to bioaccumulation of GLA-IONPs in the B. glabrata. These results can be useful for the development of eco-friendly nanotechnologies.

Magnetite (Fe3O4) Nanoparticles in Biomedical Application: From Synthesis to Surface Functionalisation

Nanotechnology has gained much attention for its potential application in medical science. Iron oxide nanoparticles have demonstrated a promising effect in various biomedical applications. In particular, magnetite (Fe3O4) nanoparticles are widely applied due to their biocompatibility, high magnetic susceptibility, chemical stability, innocuousness, high saturation magnetisation, and inexpensiveness. Magnetite (Fe3O4) exhibits superparamagnetism as its size shrinks in the single-domain region to around 20 nm, which is an essential property for use in biomedical applications. In this review, the application of magnetite nanoparticles (MNPs) in the biomedical field based on different synthesis approaches and various surface functionalisation materials was discussed. Firstly, a brief introduction on the MNP properties, such as physical, thermal, magnetic, and optical properties, is provided. Considering that the surface chemistry of MNPs plays an important role in the practical implementation of in vitro and in vivo applications, this review then focuses on several predominant synthesis methods and variations in the synthesis parameters of MNPs. The encapsulation of MNPs with organic and inorganic materials is also discussed. Finally, the most common in vivo and in vitro applications in the biomedical world are elucidated. This review aims to deliver concise information to new researchers in this field, guide them in selecting appropriate synthesis techniques for MNPs, and to enhance the surface chemistry of MNPs for their interests.

Detection of food spoilage and adulteration by novel nanomaterial-based sensors

Food industry is always looking for more innovative and accurate ways to monitor the food safety and quality control of final products. Current detection techniques of analytes are costly and time-consuming, and occasionally require professional experts and specialized tools. The usage of nanomaterials in sensory systems has eliminated not only these drawbacks but also has advantages such as higher sensitivity and selectivity. This article first presents a general overview of the current studies conducted on the detection of spoilage and adulteration in foods from 2015 to 2020. Then, the sensory properties of nanomaterials including metal and magnetic nanoparticles, carbon nanostructures (nanotubes, graphene and its derivatives, and nanofibers), nanowires, and electrospun nanofibers are presented. The latest investigations and advancements in the application of nanomaterial-based sensors in detecting spoilage (food spoilage pathogens, toxins, pH changes, and gases) and adulterants (food additives, glucose, melamine, and urea) have also been discussed in the following sections. To conclude, these sensors can be applied in the smart packaging of food products to meet the demand of consumers in the new era.

Recent developments in enzyme immobilization technology for high-throughput processing in food industries

The demand for food and beverage markets has increased as a result of population increase and in view of health awareness. The quality of products from food processing industry has to be improved economically by incorporating greener methodologies that enhances the safety and shelf life via the enzymes application while maintaining the essential nutritional qualities. The utilization of enzymes is rendered more favorable in industrial practices via the modification of their characteristics as attested by studies on enzyme immobilization pertaining to different stages of food and beverage processing; these studies have enhanced the catalytic activity, stability of enzymes and lowered the overall cost. However, the harsh conditions of industrial processes continue to increase the propensity of enzyme destabilization thus shortening their industrial lifespan namely enzyme leaching, recoverability, uncontrollable orientation and the lack of a general procedure. Innovative studies have strived to provide new tools and materials for the development of systems offering new possibilities for industrial applications of enzymes. Herein, an effort has been made to present up-to-date developments on enzyme immobilization and current challenges in the food and beverage industries in terms of enhancing the enzyme stability.

Immobilization of Naringinase from Aspergillus Niger on a Magnetic Polysaccharide Carrier

Naringinase is an enzymatic complex used in the deglycosylation of compounds with a high application potential in the food and pharmaceutical industries. The aim of the study was to immobilize naringinase from Aspergillus niger KMS on a magnetic carrier obtained on the basis of carob gum activated by polyethyleneimine. Response surface methodology was used to optimize naringinase immobilization taking into account the following factors: pH, immobilization time, initial concentration of naringinase and immobilization temperature. The adsorption of the enzyme on a magnetic carrier was a reversible process. The binding force of naringinase was increased by crosslinking the enzyme with the carrier using dextran aldehyde. The crosslinked enzyme had better stability in an acidic environment and at a higher temperature compared to the free form. The immobilization and stabilization of naringinase by dextran aldehyde on the magnetic polysaccharide carrier lowered the activation energy, thus increasing the catalytic capacity of the investigated enzyme and increasing the activation energy of the thermal deactivation process, which confirms higher stability of the immobilized enzyme in comparison with free naringinase. The preparation of crosslinked naringinase retained over 80% of its initial activity after 10 runs of naringin hydrolysis from fresh and model grapefruit juice.

Recovery of immunoglobulin G from rabbit serum using κ-carrageenan-modified hybrid magnetic nanoparticles

Immunoglobulin G (IgG) has been used in the treatment of cancer, autoimmune diseases and neurological disorders, however, the current technologies to purify and recover IgG from biological media are of high-cost and time-consuming, resulting in high-cost products. In this sense, the search for cost-effective technologies to obtain highly pure and active IgG is highly required. The present work proposes a simple and efficient method for the purification and recovery of IgG from rabbit serum using magnetic iron oxide nanoparticles (magnetite, Fe₃O₄) coated with hybrid shells of a siliceous material modified with the anionic polysaccharide κ-carrageenan. Experimental parameters such as pH, contact time between the hybrid magnetic nanoparticles (HMNPs) and rabbit serum, and total protein concentration or dilution factor of serum were evaluated. The best results were achieved at pH 5.0, with a contact time of 60 min and using a rabbit serum with a total protein concentration of 4.8 mg·mL^-1. Under these conditions, it was obtained an IgG purification factor and adsorption yield onto the HMNPs of 3.0 and 90%, respectively. The desorption of IgG from the HMNPs was evaluated using two strategies: a KCl aqueous solution and buffered aqueous solutions. Comparing to the initial rabbit serum, an IgG purification factor of 2.7 with a recovery yield of 74% were obtained using a buffered aqueous solution at pH 7.0. After desorption, the secondary structure of IgG and other proteins was evaluated by circular dichroism and no changes in the secondary structure were observed, meaning that the IgG integrity is kept after the adsorption and desorption steps. In summary, the application of HMNPs in the purification of IgG from serum samples has a high potential as a new downstream platform.

Single-Crystalline Metal Oxide Nanostructures Synthesized by Plasma-Enhanced Thermal Oxidation

To unravel the influence of the temperature and plasma species on the growth of single-crystalline metal oxide nanostructures, zinc, iron, and copper foils were used as substrates for the study of nanostructure synthesis in the glow discharge of the mixture of oxygen and argon gases by a custom-made plasma-enhanced horizontal tube furnace deposition system. The morphology and microstructure of the resulting metal oxide nanomaterials were controlled by changing the reaction temperature from 300 to 600 °C. Experimentally, we confirmed that single-crystalline zinc oxide, copper oxide, and iron oxide nanostructures with tunable morphologies (including nanowires, nanobelts, etc.) can be successfully synthesized via such procedure. A plausible growth mechanism for the synthesis of metal oxide nanostructures under the plasma-based process is proposed and supported by the nanostructure growth modelling. The results of this work are generic, confirmed on three different types of materials, and can be applied for the synthesis of a broader range of metal oxide nanostructures.

Manipulation of Magnetic Beads with Thin Film Microelectromagnet Traps

Integration of point-of-care assays can be facilitated with the use of actuated magnetic beads (MB) to perform testing in less expensive settings to enable the delivery of cost-effective care. In this paper we present six different designs of planar microelectromagnets traps (MEMT) with four external coils in series and one central coil connected for an opposite direction of manipulation of MB in microfluidic flows. The development of a simulation tool facilitated the rapid and efficient optimization of designs by presenting the influence of system variables on real time concentrations of MB. Real time experiments are in good agreement with the simulations and showed that the design enabled synchronous concentration and dispersion of MB on the same MEMT. The yield of local concentration is seen to be highly dependent on coil design. Additional coil turns between the central and external coils (inter-windings) doubled magnetic concentration and repulsion with no significant electrical resistance increase. The assemblage of a copper microchannel closed loop cooling system to the coils successfully eliminated the thermal drift promoted by joule heating generated by applied current.