Magnetic nanomaterials for the removal,separation and preconcentration of organic and inorganic pollutants at trace levels and their practical applications: A review

The presence of organic and inorganic pollutants in nature even in very small concentrations threatens human and other living bodies health and makes it significant to remove, separate and preconcentrate these pollutants. Recently magnetic nano sorbents has been used frequently in the separation and preconcentration of these pollutants. The use of magnetic nano sorbents modified with inorganic and organic species has widespread applications in the solid phase extraction (SPE) studies due to its many unique properties. These modified nano sorbents are preferred due to their advantages such as high adsorption capacities and large surface areas. This review examined different types of magnetic materials such as magnetic carbon-based nano sorbents, inorganic nano sorbents with magnetic properties, magnetized biosorbents, magnetic metal-organic frameworks, and magnetized ionic liquids used in SPE studies. In this study, a comprehensive and systematic review of the separation and preconcentration of analytes such as heavy metal ions, drug active substances, pesticides, dyes, hormone disruptors, etc with SPE methods using magnetic nanomaterials has been revealed. Future aspects and challenges that may be encountered are discussed.     

功能化磁性纳米材料在样品前处理中的应用研究进展

随着分析化学所面临的样品性质的复杂程度越来越高,被检测物质的浓度要求越来越低,在色谱及质谱分析前进行准确、高效的样品前处理过程就显得尤为重要。磁性固相萃取法由于其合成方法简单、易于分离、萃取效率高等优点,被认为是一种高效的样品预处理方法。Fe₃O₄磁性纳米材料由于分离速度快,分散性、生物相容性好等特点,近年来被广泛用于分离分析等各个领域。为了提高Fe₃O₄磁性纳米材料的物理和化学的稳定性,使其具备更高效的吸附分离能力,需要对其进行功能化的修饰。本文综述了近年来由碳基纳米材料、分子印迹聚合物、离子液体、硼酸亲和配体、金属有机骨架、共价有机骨架、量子点、金属氧化物等功能化磁性纳米材料的制备及其在生物、环境污染物、食品样品等样品前处理中的应用,并对这一领域发展进行了展望。     

磁性纳米材料在样品前处理中的应用进展与展望

在样品前处理技术中,吸附剂材料起关键作用。随着纳米材料的发展,越来越多的纳米材料被用作吸附剂以提高对目标物的萃取效率。磁性纳米材料因其具有易于分离、表面可修饰、吸附能力强和良好的生物相容性等优异性能,已广泛应用于分析方法的样品前处理技术中。该文通过对磁性纳米材料在磁性固相萃取和在其他样品前处理技术中的研究与应用展开总结和论述,对磁性纳米材料的稳定性、作用力、比表面积及孔径调控的制备进行了阐述,展望了磁性纳米材料在分离科学中的应用前景,为进一步研究磁性纳米材料的应用提供了参考。     

石墨烯应用于样品前处理的研究进展

样品前处理技术在样品分析中发挥着越来越重要的作用,而对分析物的富集能力和对样品基体的净化程度主要取决于高效的样品前处理材料,所以发展高性能的样品前处理材料一直是该领域的前沿研究方向。近年来,各类先进材料已经被引入样品前处理领域,发展了多种高性能的萃取材料。由于独特的物理化学性质,石墨烯已在各个研究领域获得广泛关注,在样品前处理领域也发挥着重要作用。基于高的比表面积、大的π电子结构、优异的吸附性能、丰富的官能团和易于化学改性等优点,石墨烯和氧化石墨烯基萃取材料被成功应用于各种样品的前处理,对不同领域中多种类型分析物表现出优异的萃取性能。该论文总结和讨论了近3年来石墨烯材料(石墨烯、氧化石墨烯及其功能化材料)在柱固相萃取、分散固相萃取、磁性固相萃取、搅拌棒萃取、纤维固相微萃取和管内固相微萃取等方面的研究进展。基于多种萃取机理如π-π、静电、疏水、亲水、氢键等相互作用,石墨烯萃取材料能够高效萃取和选择性富集不同类别的目标分析物,如重金属离子、多环芳烃、塑化剂、雌激素、药物分子、农药残留、兽药残留等。基于新型石墨烯萃取材料的各种样品前处理技术与多种检测技术如色谱、质谱、原子吸收光谱等联用,广泛应用于环境监测、食品安全和生化分析等领域。最后,总结了石墨烯在样品前处理领域中存在的问题,并展望了未来的发展趋势。     

Modification and application of Fe3O4 nanozymes in analytical chemistry: A review

In recent years, Fe₃O₄ nanomaterials have received much attention in analytical chemistry due to their excellent magnetic and peroxidase-like activity. As the catalytic characteristics of Fe₃O₄ nanomaterials is similar to those of horseradish peroxidase (HRP), Fe₃O₄ nanomaterials are also used as peroxidase mimics and have achieved a certain development in many fields based on latest research results. To improve the stability and catalytic ability of simple Fe₃O₄ nanomaterials, various modification strategies of Fe₃O₄ nanomaterials have been developed. The recent advances of these strategies have been presented and discussed. In addition, this paper introduces the application of Fe₃O₄ nanozymes in the detection of food and industrial pollutants, as well as in the field of biosafety.     

用于食品安全分析样品前处理的共价有机聚合物的制备及应用进展

食品安全关系身体健康和生命安全,是全球关注的热点之一。食品基质复杂,痕量有毒有害物质分析之前必须经过有效的前处理。目前发展的前处理技术如固相萃取、磁固相萃取、固相微萃取等,其关键是吸附介质。共价有机聚合物是一类通过共价键连接而成的有机多孔材料,具有质轻、稳定性好、比表面积大、结构可控、易于修饰等特性,是一类优异的新型吸附材料。该文综述了近年来共价有机聚合物(COPs)在食品安全分析前处理中的应用进展。共价有机聚合物及其功能化复合材料通过简单的装填、聚合反应或化学键合固定到小柱或毛细管柱中用作固相萃取的吸附介质;通过一锅法、原位还原法、原位生长法或共沉淀法生成具有磁性的固相萃取吸附介质;或者通过物理涂覆、化学键合、溶胶凝胶法及原位生长法制备固相微萃取纤维。基于以上高吸附容量共价有机聚合物的样品前处理技术,食品中农残兽残、添加剂、环境污染物及生物毒素等得到了有效富集。最后,展望了COPs在食品分析样品前处理应用中的发展方向:简单高效绿色制备方法的开发,功能化COPs的设计合成;萃取机理的研究;高通量、高灵敏度分析方法研究。这些研究将促进COPs在样品前处理领域获得更广泛的应用。     

Nanoantioxidants: Pioneer Types,Advantages, Limitations,and Future Insights

Free radicals are generated as byproducts of normal metabolic processes as well as due to exposure to several environmental pollutants. They are highly reactive species, causing cellular damage and are associated with a plethora of oxidative stress-related diseases and disorders. Antioxidants can control autoxidation by interfering with free radical propagation or inhibiting free radical formation, reducing oxidative stress, improving immune function, and increasing health longevity. Antioxidant functionalized metal nanoparticles, transition metal oxides, and nanocomposites have been identified as potent nanoantioxidants. They can be formulated in monometallic, bimetallic, and multi-metallic combinations via chemical and green synthesis techniques. The intrinsic antioxidant properties of nanomaterials are dependent on their tunable configuration, physico-chemical properties, crystallinity, surface charge, particle size, surface-to-volume ratio, and surface coating. Nanoantioxidants have several advantages over conventional antioxidants, involving increased bioavailability, controlled release, and targeted delivery to the site of action. This review emphasizes the most pioneering types of nanoantioxidants such as nanoceria, silica nanoparticles, polydopamine nanoparticles, and nanocomposite-, polysaccharide-, and protein-based nanoantioxidants. This review overviews the antioxidant potential of biologically synthesized nanomaterials, which have emerged as significant alternatives due to their biocompatibility and high stability. The promising nanoencapsulation nanosystems such as solid lipid nanoparticles, nanostructured lipid carriers, and liposome nanoparticles are highlighted. The advantages, limitations, and future insights of nanoantioxidant applications are discussed.     

Emerging food contaminants: a review

Governments throughout the world are intensifying their efforts to improve food safety. These efforts come as a response to an increasing number of food-safety problems and increasing consumer concerns. In addition, the variety of toxic residues in food is continuously increasing as a consequence of industrial development, new agricultural practices, environmental pollution, and climate change. This paper reviews a selection of emerging contaminants in food, including the industrial organic pollutants perfluorinated compounds (PFCs), polybrominated diphenyl ethers (PBDEs), and nanomaterials; the pharmaceutical residues antibiotics and coccidiostats; and emerging groups of marine biotoxins. The main analytical approaches for their detection and quantification in food will be presented and discussed with special emphasis on biological techniques, when these are feasible. In the last section, a summary of recent publications reporting the concentrations of these compounds in food will be presented and discussed.     

New advances in electrochemical biosensors for the detection of toxins: Nanomaterials,magnetic beads and microfluidics systems. A review

The use of nanotechnology in bioanalytical devices has special advantages in the detection of toxins of interest in food safety and environmental applications. The low levels to be detected and the small size of toxins justify the increasing number of publications dealing with electrochemical biosensors, due to their high sensitivity and design versatility. The incorporation of nanomaterials in their development has been exploited to further increase their sensitivity, providing simple and fast devices, with multiplexed capabilities. This paper gives an overview of the electrochemical biosensors that have incorporated carbon and metal nanomaterials in their configurations for the detection of toxins. Biosensing systems based on magnetic beads or integrated into microfluidics systems have also been considered because of their contribution to the development of compact analytical devices. The roles of these materials, the methods used for their incorporation in the biosensor configurations as well as the advantages they provide to the analyses are summarised.     

Anthocyanins Recovered from Agri-Food By-Products Using Innovative Processes: Trends,Challenges, and Perspectives for Their Application in Food Systems

Anthocyanins are naturally occurring phytochemicals that have attracted growing interest from consumers and the food industry due to their multiple biological properties and technological applications. Nevertheless, conventional extraction techniques based on thermal technologies can compromise both the recovery and stability of anthocyanins, reducing their global yield and/or limiting their application in food systems. The current review provides an overview of the main innovative processes (e.g., pulsed electric field, microwave, and ultrasound) used to recover anthocyanins from agri-food waste/by-products and the mechanisms involved in anthocyanin extraction and their impacts on the stability of these compounds. Moreover, trends and perspectives of anthocyanins’ applications in food systems, such as antioxidants, natural colorants, preservatives, and active and smart packaging components, are addressed. Challenges behind anthocyanin implementation in food systems are displayed and potential solutions to overcome these drawbacks are proposed.     

Micro-extraction of Xenobiotics and Biomolecules from Different Matrices on Nanostructures

Sample preparation is the backbone of any analytical procedure; it involves extraction and pre-concentration of the desired analytes; often at trace levels. The present article describes the applications of nanomaterials (carbon-based inorganic and polymeric materials) in miniaturized extraction such as solid phase micro-extraction, stir-bar sorptive extraction, liquid phase micro-extraction, and dispersive liquid phase micro-extraction in the analyses of aqueous samples. The nanoparticles used for micro-extractions are discussed on the basis of their chemical natures. The synthetic route and the preparation of nanomaterials are described along with the optimization strategies for micro-extraction. A comparison between the conventional materials and nanomaterials for micro-extraction is proposed. The key roles of the nanomaterials for the micro-extraction of different analytes such as drugs, pesticides, polycyclic aromatic hydrocarbons, proteins and peptides from aqueous samples are reported. The use of nanomaterials, combined with miniaturized micro-extraction techniques, proved to be highly promising for sample preparation of various matrices with analytes at trace levels.     

Application of derivatized magnetic materials to the separation and the preconcentration of pollutants in water samples

Monitoring pollutants in water samples is a challenge to analysts. In recent years, separation technology based on magnetic materials has received considerable attention. This article reviews the literature dealing with the application of magnetic materials, combined with other materials (e.g., silica, octadecylsilane, polymers and surfactants), to the separation and the preconcentration of pollutants in water samples. The magnetic extraction method is not only convenient, economical and highly efficient, but it also overcomes problems with conventional solid-phase extraction, (e.g., packing of sorbent into the column and time-consuming loading of large-volume samples).     

离子液体基磁性固相萃取技术的研究进展

磁性固相萃取(Magnetic solid-phase extraction,MSPE)是一种采用磁性材料作为吸附剂的新型样品前处理技术,发展新型的磁性材料作为吸附剂是MSPE领域的研究热点。用离子液体(Ionic liquid,IL)修饰磁性材料作为吸附剂既具有MSPE操作简单、萃取快速、基质干扰小的优点,又兼具IL结构的可设计性和易功能化的优点,在样品前处理领域引起了广泛关注。该文综述了IL修饰磁性吸附剂的制备方法(物理涂敷、化学键合和包埋法),IL-MSPE的萃取方式(传统的MSPE,混合半胶束-MSPE和分散液液微萃取-MSPE),以及IL-MSPE在有机污染物、金属离子和生物活性物质萃取分离中的应用,并对该技术的发展趋势进行了展望。     

Environmentally Friendly Techniques and Their Comparison in the Extraction of Natural Antioxidants from Green Tea,Rosemary, Clove,and Oregano

Many current food and health trends demand the use of more ecological, sustainable, and environmentally friendly techniques for the extraction of bioactive compounds, including antioxidants. However, extraction yields and final antioxidant activities vary between sources and are highly influenced by the given extraction method and nature and ratio of the employed solvent, especially for total polyphenols, flavonoids, and anthocyanins, which are well recognized as natural antioxidants with food applications. This review focused on the most common extraction techniques and potential antioxidant activity in the food industry for various natural antioxidant sources, such as green tea, rosemary, clove, and oregano. Green extraction techniques have been proven to be far more efficient, environmentally friendly, and economical. In general, these techniques include the use of microwaves, ultrasound, high hydrostatic pressure, pulsed electric fields, enzymes, and deep eutectic solvents, among others. These extraction methods are described here, including their advantages, disadvantages, and applications.     

Antibacterial Nanomaterials: Mechanisms,Impacts on Antimicrobial Resistance and Design Principles

Antimicrobial resistance (AMR) is one of the biggest threats to the environment and health. AMR rapidly invalidates conventional antibiotics, and antimicrobial nanomaterials have been increasingly explored as alternatives. Interestingly, several antimicrobial nanomaterials show AMR-independent antimicrobial effects without detectable new resistance and have therefore been suggested to prevent AMR evolution. In contrast, some are found to trigger the evolution of AMR. Given these seemingly conflicting findings, a timely discussion of the two faces of antimicrobial nanomaterials is urgently needed. This review systematically compares the killing mechanisms and structure-activity relationships of antibiotics and antimicrobial nanomaterials. We then focus on nano-microbe interactions to elucidate the impacts of molecular initiating events on AMR evolution. Finally, we provide an outlook on future antimicrobial nanomaterials and propose design principles for the prevention of AMR evolution.     

Water treatment: functional nanomaterials and applications from adsorption to photodegradation

Global efforts for engineering desired materials which are able to treat the water sources still are ongoing in the bench level methods. Considering adsorbent and photocatalytic materials as the main reliable candidates still are encountering with struggles because of many challenges that restrict their large-scale application. This review comprehensively considered the recent advanced materials water treatment methods which involve to magnetic, activated carbon, carbon nanotubes (CNTs), graphene (G), graphene oxide (GO), (Graphene) quantum dots, carbon nanorods, carbon nano-onions, and reduced graphene oxide (RGO), zeolite, silica and clay-based nanomaterials. The adsorption and photocatalytic properties of these nanomaterials introduced them as highly potent option for heavy metal ions and organic dyes removal and photocatalytic degradation. High specific surface area in conjugation with presenting higher kinetics of adsorption and decomposition are the main characteristics of these materials which make them appropriate to treat wastewater even in ultralow concentration of the pollutants. Considering the mechanistic aspects of the adsorption and photocatalytic decomposition process, challenges and opportunities were other subjects that have been highlighted for the discussed nanomaterials. In term of the adsorption approaches, the mechanism of adsorptions and their influence on the maximum adsorption capacity were discussed and also for photocatalyst approach the radical active spices and their role in kinetic and efficiency of the organic pollutant decomposition were provided a deep discussion.     

Nanoparticle-based immunosensors and immunoassays for aflatoxins

Aflatoxins are naturally existing mycotoxins produced mainly by Aspergillus flavus and Aspergillus parasiticus, present in a wide range of food and feed products. Because of their extremely high toxicity and carcinogenicity, strict control of maximum residue levels of aflatoxins in foodstuff is set by many countries. In daily routine, different chromatographic methods are used almost exclusively. As supplement, in several companies enzyme immunoassay-based sample testing as primary screening is performed. Recently, nanomaterials such as noble metal nanoparticles, magnetic particles, carbon nanomaterials, quantum dots, and silica nanomaterials are increasingly utilized for aflatoxin determination to improve the sensitivity and simplify the detection. They are employed either as supports for the immobilization of biomolecules or as electroactive or optical labels for signal transduction and amplification. Several nanoparticle-based electrochemical, piezoelectric, optical, and immunodipstick assays for aflatoxins have been developed. In this review, we summarize these recent advances and illustrate novel concepts and promising applications in the field of food safety.     

Synthesis and Applications of Functionalized Magnetic Nanomaterials in Enantioseparation

Efficient enantioselective separation is a challenging task due to the identical physical and chemical properties of enantiomers. Functionalized magnetic nanomaterials modified with chiral ligands on their surface possess both magnetic property and chiral recognition ability, and have demonstrated great potential in chiral discrimination. This review summarizes the applications of magnetic nanomaterials modified with various chiral selectors (e.g., β-cyclodextrins, polymers, proteins, amino acids and cellulose) in enantioselective separation. After proper preparation and modification, these functionalized magnetic nanomaterials are effective for enantioseparation. Therefore, enantioseparations based on functionalized magnetic nanomaterials are convenient, economical and effective.     

Advantages of Carbon Nanomaterials in Electrochemical Aptasensors for Food Analysis

Electrochemical aptasensors appear as promising tools in food analysis, able to provide sensitive, fast and cost‐effective analysis, with the added advantage of portability. Carbon nanomaterials and in particular carbon nanotubes and graphene are among the nanomaterials most often used to build electrochemical aptasensors due to their good electrical conductivity, large surface area and multiple functionalisation possibilities. This review aims to give an overview of the types of carbon nanomaterials and their composites which have been used to enhance the performance of electrochemical aptasensors. Examples are detailed for the biosensors which were tested with real food samples. In these aptasensors, carbon nanomaterials have played different roles, from facilitating the immobilization of high amounts of aptamer and enhancing the electroactive area of the sensors to roles as nanocarrier for signaling probes in amplification schemes or even as electroactive probes generating the output signal. The survey of recent literature shows a positive evolution towards increased aptasensor testing with food samples. However, many challenges remain related to the better characterization of nanomaterials used, clarifying the roles of specific components in multi‐component nanocomposites and widening the types of food matrices and analytes tested with the aptasensors. Although we are still far from knowing when these novel tools will replace classic analytical methods in food analysis, carbon nanomaterials will certainly continue to play an important role in the design of future electrochemical aptasensors for food analysis.     

Recent Progress in Two-Dimensional Antimicrobial Nanomaterials

Nowadays, microorganisms, including bacteria and viruses, are regarded as new environmental pollutants and pose serious threats to public health. Yet, traditional disinfection approaches for bacteria and viruses are generally ineffective. Furthermore, they exhibit the disadvantages of high-energy consumption, environmental pollution, high cost, and toxic byproduct generation. In this respect, nanomaterials display promising antimicrobial capabilities due to their unique properties and provide solutions to the abovementioned issues. Herein, recent progress in the development of 2D nanomaterials displaying antimicrobial capabilities is highlighted. The structures, morphologies, and performances of essential metal, graphene, and nitride-based 2D antibacterial nanomaterials are summarized in detail. In addition, possible antimicrobial mechanisms and the relationship between structure and antimicrobial efficiency are elaborated.