Enantiomeric separation by microchip electrophoresis using bovine serum albumin conjugated magnetic core-shell Fe3 O4 @Au nanocomposites as stationary phase

Green Synthesis of Au Magnetic Nanocomposites Using Waste Chestnut Skins and Their Application as a Peroxidase Mimic Nanozyme Electrochemical Sensing Platform for Sodium Nitrite

An electrochemical sensor with high sensitivity for the detection of sodium nitrite was constructed based on the peroxidase-like activity of Au magnetic nanocomposites (Au@Fe3O4). The Au@Fe3O4 composite nanoparticles were green-synthesized via the reduction of gold nanoparticles (AuNPs) from waste chestnut skins combined with the sonochemical method. The nanoparticles have both the recoverability of Fe3O4 and the advantage of being able to amplify electrical signals. Furthermore, the synergistic effect of green reduction and sonochemical synthesis provides a functional approach for the preparation of Au@Fe3O4 with significant peroxidase-like activities. The physicochemical properties were characterized using transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), the Brunauer-Emmett-Teller (BET) method, and Fourier transform infrared spectroscopy (FT-IR). The electrochemical properties of sodium nitrite were determined with cyclic voltammetry (CV) and chronoamperometry (i-t). The results revealed that Au@Fe3O4 acted as a peroxidase mimic to decompose hydrogen peroxide to produce free radicals, while ·OH was the primary free radical that promoted the oxidation of sodium nitrite. With the optimal detection system, the constructed electrochemical sensor had a high sensitivity for sodium nitrite detection. In addition, the current response had a good linear relationship with the sodium nitrite concentration in the range of 0.01-100 mmol/L. The regression equation of the working curve was y = 1.0752x + 4.4728 (R2 = 0.9949), and the LOD was 0.867 μmol/L (S/N = 3). Meanwhile, the constructed detection system was outstanding in terms of recovery and anti-interference and had a good detection stability of more than 96.59%. The sensor has been successfully applied to a variety of real samples. In view of this, the proposed novel electrochemical analysis method has great prospects for application in the fields of food quality and environmental testing.

From capillaries to microchips, green electrophoretic features for enantiomeric separations: A decade review (2013-2022)

Enantioseparation by the electromigration-based method is well-established and widely discussed in the literature. Electrophoretic strategies have been used to baseline resolve complex enantiomeric mixtures, typically using a selector substance into the background electrolyte (BGE) from capillaries to microchips. Along with developing new materials/substances for enantioseparations, it is the concern about the green analytical chemistry (GAC) principles for method development and application. This review article brings a last decade's update on the publications involving enantioseparation by electrophoresis for capillary and microchip systems. It also brings a critical discussion on GAC principles and new green metrics in the context of developing an enantioseparation method. Chemical and green features of native and modified cyclodextrins are discussed. Still, given the employment of greener substances, ionic liquids and deep-eutectic solvents are highlighted, and some new selectors are proposed. For all the mentioned selectors, green features about their production, application, and disposal are considered. Sample preparation and BGE composition in GAC perspective, as well as greener derivatization possibilities, were also addressed. Therefore, one of the goals of this review is to aid the electrophoretic researchers to look where they have not.

Surface modified nanoparticles and their applications for enantioselective detection, analysis, and separation of various chiral compounds

The development of efficient enantioselective detection, analysis, and separation relies significantly on molecular interaction. In the scale of molecular interaction, nanomaterials have a significant influence on the performance of enantioselective recognitions. The use of nanomaterials for enantioselective recognition involved synthesizing new materials and immobilization techniques to produce various surface-modified nanoparticles that are either encapsulated or attached to surfaces, as well as layers and coatings. The combination of surface-modified nanomaterials and chiral selectors can improve enantioselective recognition. This review aims to offer engagement insights into the production and application of surface-modified nanomaterials to achieve sensitive and selective detection, better chiral analysis, and separation of numerous chiral compounds.

Enantioseparation/Recognition based on nano techniques/materials

Enantiomers show different behaviors in interaction with the chiral environment. Due to their identical chemical structure and their wide application in various industries, such as agriculture, medicine, pesticide, food, and so forth, their separation is of great importance. Today, the term "nano" is frequently encountered in all fields. Technology and measuring devices are moving towards miniaturization, and the usage of nanomaterials in all sectors is expanding substantially. Given that scientists have recently attempted to apply miniaturized techniques known as nano-liquid chromatography/capillary-liquid chromatography, which were originally accomplished in 1988, as well as the widespread usage of nanomaterials for chiral resolution (back in 1989), this comprehensive study was developed. Searching the terms "nano" and "enantiomer separation" on scientific websites such as Scopus, Google Scholar, and Web of Science yields articles that either use miniaturized instruments or apply nanomaterials as chiral selectors with a variety of chemical and electrochemical detection techniques, which are discussed in this article.

Chiral magnetic hybrid materials constructed from macromolecules and their chiral applications

Chirality is a fundamental and ubiquitous feature of living organisms in nature. Magnetic materials, in particular magnetic nanoparticles (MNPs), show some interesting properties such as large specific surface area, easy surface modification, magnetic responsivity and separation ability. Integrating MNPs with chirality in a single material will undoubtedly create a large number of advanced multi-functional materials. Despite the great advancements made in this area, there have been no review articles to summarize the relevant studies. The present work reviews the major progress recently made in constructing chiral magnetic hybrid materials (CMHMs) using macromolecules, which are classified based on the primary chiral macromolecular organic components, namely, biological polymers and synthetic polymers, and the applications of the resulting chiral hybrids in chiral research fields, including asymmetric catalysis, enzymatic resolution, chromatographic separation, enantioselective crystallization and enantioselective adsorption, are also summarized. The challenges and prospects of related research fields are proposed in the last section.

Recent Advances in Inorganic Nanomaterials Synthesis Using Sonochemistry: A Comprehensive Review on Iron Oxide, Gold and Iron Oxide Coated Gold Nanoparticles

Sonochemistry uses ultrasound to improve or modify chemical reactions. Sonochemistry occurs when the ultrasound causes chemical effects on the reaction system, such as the formation of free radicals, that intensify the reaction. Many studies have investigated the synthesis of nanomaterials by the sonochemical method, but there is still very limited information on the detailed characterization of these physicochemical and morphological nanoparticles. In this comprehensive review, recent advances in the sonochemical synthesis of nanomaterials based on iron oxide nanoparticles (Fe3O4NP), gold nanoparticles (AuNP) and iron oxide-coated gold nanoparticles (Fe3O4@Au NP) are discussed. These materials are the most studied materials for various applications, such as medical and commercial uses. This review will: (1) address the simple processing and observations on the principles of sonochemistry as a starting point for understanding the fundamental mechanisms, (2) summarize and review the most relevant publications and (3) describe the typical shape of the products provided in sonochemistry. All in all, this review's main outcome will provide a comprehensive overview of the available literature knowledge that promotes and encourages future sonochemical work.

Recent advances in microchip enantioseparation and analysis

This review summarizes recent developments (over the past decade) in the field of microfluidics-based solutions for enantiomeric separation and detection. The progress in various formats of microchip electrodriven separations, such as MCE, microchip electrochromatography, and multidimensional separation techniques, is discussed. Innovations covering chiral stationary phases, surface coatings, and modification strategies to improve resolution, as well as integration with detection systems, are reported. Finally, combinations with other microfluidic functional units are also presented and highlighted.

Mechanisms of effective gold shell on Fe3O4 core nanoparticles formation using sonochemistry method

Sonochemical synthesis (sonochemistry) is one of the most effective techniques of breaking down large clusters of nanoparticles (NPs) into smaller clusters or even individual NPs, which ensures their dispersibility (stability) in a solution over a long duration. This paper demonstrates the potential of sonochemistry becoming a valuable tool for the deposition of gold (Au) shell on iron oxide nanoparticles (Fe₃O₄ NPs) by explaining the underlying complex processes that control the deposition mechanism. This review summarizes the principles of the sonochemistry method and highlights the resulting phenomenon of acoustic cavitation and its associated physical, chemical and thermal effects. The effect of sonochemistry on the deposition of Au NPs on the Fe₃O₄ surface of various sizes is presented and discussed. A Vibra-Cell ultrasonic solid horn with tip size, frequency, power output of ½ inch, 20 kHz and 750 W respectively was used in core@shell synthesis. The sonochemical process was shown to affect the surface and structure of Fe₃O₄ NPs via acoustic cavitation, which prevents the agglomeration of clusters in a solution, resulting in a more stable dispersion. Deciphering the mechanism that governs the formation of Au shell on Fe₃O₄ core NPs has emphasized the potential of sonication in enhancing the chemical activity in solutions.

Open-tubular Capillary Electrochromatography with Janus Structured Au-Fe3O4 Nanoparticles Coating as Stationary Phase

A novel Au-Fe₃O₄ nanoparticles-based capillary column was fabricated by magnetic approach for open-tubular capillary electrochromatography (OT-CEC). The bifunctional dumbbell-like Janus Au-Fe₃O₄ nanoparticles (Au-Fe₃O₄ NPs) were prepared through a hydrothermal synthesis strategy, and the morphology was characterized by transmission electron microscopy (TEM). Multilayers Au-Fe₃O₄ NPs were easily coated onto the inner surface of silica capillary by an external magnetic field to generate an Au-Fe₃O₄ NPs-based column. Compared with a bare capillary, the modified surface exhibited more stable and suppressed electroosmotic mobility. The column showed good separation efficiency for neutral analytes in the OT-CEC separation mode, with theoretical plate numbers of up to 79705 per meter for naphthalene. The successful separation of dihydroxy benzene isomers and proteins demonstrated that the column exhibits a reasonable separation performance. The reproducibility of the Au-Fe₃O₄ NPs capillary was studied, with relative standard deviations (RSD) for day-to-day and column-to-column less than 1 and 1.75%, respectively.

Open-tubular capillary electrochromatography with β-cyclodextrin-functionalized magnetic nanoparticles as stationary phase for enantioseparation of dansylated amino acids

Magnetic nanoparticles (MNPs) modified with β-cyclodextrin and mono-6-deoxy-6-(1-methylimidazolium)-β-cyclodextrin tosylate (an ionic liquid), which called MNP-β-CD and MNP-β-CD-IL, were coated into the capillary inner wall. Compared to an uncoated capillary, the new systems show good reproducibility and durability. The systems based on the use of MNP-β-CD or MNP-β-CD-IL as stationary phases were established for enantioseparation of Dns-modified amino acids. Improved resolutions were obtained for both CEC systems. Primary parameters such as running buffer pH value and applied voltage were systematically optimized in order to obtain optimal enantioseparations. Under the optimized conditions, the capillaries exhibited excellent chiral recognition ability for six Dns-amino acids (the DL-forms of alanine, leucine, lsoleucine, valine, methionine, glutamic acid) and provided a promising way for the preparation of chiral column. Graphical Abstract Schematic presentation of the open-tubular capillary electrochromatography systems with MNP-β-CD and MNP-β-CD-IL as stationary phases for enantioseparation of dansylated amino acids.

Novel approaches for biomolecule immobilization in microscale systems

This manuscript reviews novel approaches applied for biomolecule immobilization in microscale systems.

Synthesis and characterization of magnetite nanoparticles having different cover layer and investigation of cover layer effect on the adsorption of lysozyme and bovine serum albumin

In this study, differently coated superparamagnetic Fe₃O₄ (magnetite) nanoparticles were synthesized, characterized and used for lysozyme (Ly) and bovine serum albumin (BSA) adsorption. SiO₂, carbon nanotubes (CNTs) and graphene were used for covering the readily synthesized magnetite nanoparticles to elucidate the effect of cover layer on the protein adsorption kinetics and capacities of nanostructure. XRD, FTIR, AFM, SEM, VSM and fluorescence measurements were used for the characterization of the samples and investigating the adsorption kinetics of Ly and BSA by these nanoparticles. The average particle size of the Fe₃O₄ nanoparticles are approximately found as 10nm and VSM measurement shows that the Fe₃O₄ particles have superparamagnetic behavior with no hysteresis and remnant. The adsorption kinetic of proteins on nanosized material is followed via fluorescence method. All the nanostructures with different cover layers obey pseudo first order kinetics and SiO₂ coated nanoparticles show the fastest kinetics and capabilities for Ly and BSA adsorption.

Block copolymer conjugated Au-coated Fe3O4 nanoparticles as vectors for enhancing colloidal stability and cellular uptake

BACKGROUND

Polymer surface-modified inorganic nanoparticles (NPs) provide a multifunctional platform for assisting gene delivery. Rational structure design for enhancing colloidal stability and cellular uptake is an important strategy in the development of safe and highly efficient gene vectors.

RESULTS

Heterogeneous Au-coated Fe3O4 (Fe3O4@Au) NPs capped by polyethylene glycol-b-poly1-(3-aminopropyl)-3-(2-methacryloyloxy propylimidazolium bromine) (PEG-b-PAMPImB-Fe3O4@Au) were prepared for DNA loading and magnetofection assays. The Au outer shell of the NPs is an effective platform for maintaining the superparamagnetism of Fe3O4 and for PEG-b-PAMPImB binding via Au-S covalent bonds. By forming an electrostatic complex with DNA at the inner PAMPImB shell, the magnetic nanoplexes offer steric protection from the outer corona PEG, thereby promoting high colloidal stability. Transfection efficiency assays in human esophageal cancer cells (EC109) show that the nanoplexes have high transfection efficiency at a short incubation time in the presence of an external magnetic field, due to increased cellular internalization via magnetic acceleration. Finally, after transfection with the magnetic nanoplexes EC109 cells acquire magnetic properties, thus allowing for selective separation of transfected cells.

CONCLUSION

Precisely engineered architectures based on neutral-cationic block copolymer-conjugated heterogeneous NPs provide a valuable strategy for improving the applicability and efficacy of synthesized vectors.

Enantioseparations in open-tubular capillary electrochromatography: Recent advances and applications

This review highlights recent advances and applications in open-tubular capillary electrochromatography (OT-CEC) for enantioseparations during the last decade. Although extensive research has been conducted in the area of separations by use of CEC, and a big number of reviews have been published, there is not a review on exclusively the use of chiral stationary phases (CSPs) in OT-CEC for enantioseparations. Therefore, in this review, the design and synthesis of different CSPs are presented, and their potential applications in OT-CEC for enantioseparations are discussed. The different approaches to CSP development include chiral nanomaterials, porous layers, molecular imprinting, sol-gel technique, polyelectrolyte multilayer coating, polymeric coating and others.

Improving the sensitivity in chiral capillary electrophoresis

CE is known for being one of the most powerful analytical techniques when performing enantioseparations due to its numerous advantages such as excellent separation efficiency and extremely low solvents and reagents consumption, all of them derived from the capillary small dimensions. Moreover, it is worth highlighting that unlike in chromatographic techniques, in CE the chiral selector is generally within the separation medium instead of being attached to the separation column which makes the method optimization a more versatile task. Despite its numerous advantages, when using UV-Vis detection, CE lacks of sensitivity detection due to its short optical path length derived from the narrow separation capillary. This issue can be overcome by means of different approaches, either by sample treatment procedures or by in-capillary preconcentration techniques or even by employing detection systems more sensitive than UV-Vis, such as LIF or MS. The present review assembles the latest contributions regarding improvements of sensitivity in chiral CE published from June 2013 until May 2015, which follows the works included in a previous review reported by Sánchez-Hernández et al. [Electrophoresis 2014, 35, 12-27].