Synthesis of Morphology Processable α‐AlPO4 Nanoparticles,Nanowires, and Multi‐strand Nano‐ropes

In this paper we present aluminum phosphate nanocrystals, prepared by a hydrothermal reaction, using amphiphilic triblock copolymer F127 [(EO)₁₀₆(PO)₇₀(EO)₁₀₆] as a morphology‐directing template. By verifying the pH from 10 to 12, the morphology progression of AlPO₄ nanocrystals from nanoparticles to nanoparticle‐aggregated nanowires, and finally to multi‐strand nano‐ropes, was successfully demonstrated. The most influential factors in the morphology process were the initial pH level, the participation of surfactant‐template F127, and the change in pH during the reaction. We proposed a pH‐dependent model to illustrate both the growth of AlPO₄ nanocrystals inside F127 amphiphilic domains and the chemical driving force that aggregated the nanoparticles into chain‐shaped nanowires. The incorporation of water molecules as H‐bonding linkers, to combine single nanowires into multi‐strand nano‐ropes, is also discussed in this model. Powder X‐ray diffraction (XRD) patterns of the nanoparticle‐aggregated nanowires and multi‐strand nano‐ropes were consistent with a mixed phase of berlinite and cristobalite structures, corresponding to the low‐temperature form (a‐form), while the AlPO₄ nanoparticles showed a pure berlinite phase only.     

Nanocomposite Incorporating V2O5 Nanowires and Gold Nanoparticles for Mimicking an Enzyme Cascade Reaction and Its Application in the Detection of Biomolecules

Artificial enzyme mimics are a current research interest, and many nanomaterials have been found to display enzyme‐mimicking activity. However, to the best of our knowledge, there have not hitherto been any reports on the use of pure nanomaterials to construct a system capable of mimicking an enzyme cascade reaction. Herein, we describe the construction of a novel nanocomposite consisting of V₂O₅ nanowires and gold nanoparticles (AuNPs) through a simple and facile chemical method, in which V₂O₅ and AuNPs possess intrinsic peroxidase and glucose oxidase (GOx)‐like activity, respectively. Results suggest that this material can mimic the enzyme cascade reaction of horseradish peroxidase (HRP) and GOx. Based on this mechanism, a direct and selective colorimetric method for the detection of glucose has been successfully designed. Because single‐strand and double‐strand DNA (ssDNA and dsDNA) have different deactivating effects on the GOx‐like activity of AuNPs, the sensing of target complementary DNA can also be realized and disease‐associated single‐nucleotide polymorphism of DNA can be easily distinguished. Our study opens a new avenue for the use of nanomaterials in enzyme mimetics, and holds promise for the further exploration of nanomaterials in creating alternative catalytic systems to natural enzymes.     

Circular dichroism study of enzymatic manipulation on magnetic and metallic DNA template nanowires

Circular dichroism spectroscopy (CD) was used to examine the mechanism of endonuclease clipping and ligation of the DNA template nanowires. The biomolecular manipulation of the DNA template is compared for both metallic (Au) and magnetic (Fe₂O₃ and CoFe₂O₄) nanowires. The dependence of nanoparticle (NP) concentration on enzymatic clipping and DNA ligation was studied, in addition to performing absorbance and thermal melting experiments. Low-NP concentration preserved and digested the DNA template structure. Yet, at higher NP concentrations, the DNA template began to denature before enzyme addition. It was also observed that ligation of the digested DNA occurred more efficiently at low-NP concentrations. These results provide significant information on structural alteration and biorecognition effectiveness of the DNA template after enzymatic manipulation.     

Circular dichroism study of enzymatic manipulation on magnetic and metallic DNA template nanowires

Circular dichroism spectroscopy (CD) was used to examine the mechanism of endonuclease clipping and ligation of the DNA template nanowires. The biomolecular manipulation of the DNA template is compared for both metallic (Au) and magnetic (Fe₂O₃ and CoFe₂O₄) nanowires. The dependence of nanoparticle (NP) concentration on enzymatic clipping and DNA ligation was studied, in addition to performing absorbance and thermal melting experiments. Low-NP concentration preserved and digested the DNA template structure. Yet, at higher NP concentrations, the DNA template began to denature before enzyme addition. It was also observed that ligation of the digested DNA occurred more efficiently at low-NP concentrations. These results provide significant information on structural alteration and biorecognition effectiveness of the DNA template after enzymatic manipulation.     

6‐TIPS‐β‐Cyclodextrin‐Modified Fe3O4 for Facile Enantioseparation of 1‐(1‐Naphthyl)ethylamine

A new type of chiral magnetic nanoparticle was prepared from covalently linked magnetic nanoparticles (Fe₃O₄) and heptakis‐(6‐O‐triisopropylsilyl)‐β‐cyclodextrin (6‐TIPS‐β‐CD). The resulting selectors (TIPS‐β‐CD‐MNPs) combined the good magnetic properties Fe₃O₄ and efficient chiral recognition ability of 6‐TIPS‐β‐CD. The enantioselectivity of TIPS‐β‐CD‐MNPs towards 1‐(1‐naphthyl)ethylamine was six times higher than that of the parent β‐CD modified Fe₃O₄ particles.     

Supramolecular Fluorescent Nanoparticles Constructed via Multiple Non‐Covalent Interactions for the Detection of Hydrogen Peroxide in Cancer Cells

Overabundance of hydrogen peroxide originating from environmental stress and/or genetic mutation can lead to pathological conditions. Thus, the highly sensitive detection of H₂O₂ is important. Herein, supramolecular fluorescent nanoparticles self‐assembled from fluorescein isothiocyanate modified β‐cyclodextrin (FITC‐β‐CD)/rhodamine B modified ferrocene (Fc‐RB) amphiphile were prepared through host–guest interaction between FITC‐β‐CD host and Fc‐RB guest for H₂O₂ detection in cancer cells. The self‐assembled nanoparticles based on a combination of multiple non‐covalent interactions in aqueous medium showed high sensitivity to H₂O₂ while maintaining stability under physiological condition. Owing to the fluorescence resonance energy transfer (FRET) effect, addition of H₂O₂ led to obvious fluorescence change of nanoparticles from red (RB) to green (FITC) in fluorescent experiments. In vitro study showed the fluorescent nanoparticles could be efficiently internalized by cancer cells and then disrupted by endogenous H₂O₂, accompanying with FRET from “on” to “off”. These supramolecular fluorescent nanoparticles constructed via multiple non‐covalent interactions are expected to have potential applications in diagnosis and imaging of diseases caused by oxidative stresses.     

Vertically Aligned CuO Nanowires Based Electrode for Amperometric Detection of Hydrogen Peroxide

Vertically aligned copper oxide (CuO) nanowires were synthesized by directly heating copper foil on a hotplate under ambient conditions. The as‐grown CuO nanowires film is mechanically stable and was facilely attached to a glassy carbon (GC) electrode, offering an excellent electrochemical sensing platform. The CuO nanowires electrode shows excellent electrocatalytic response to H₂O₂ with significantly lower overpotentials for its oxidation and reduction and also exhibits a fast response and high sensitivity for the amperometric detection of H₂O₂. The novel vertically aligned CuO nanowires electrode is readily applicable to other analytes and has great potential applications in the electrochemical detection.     

Protease Immobilization on γ‐Fe2O3/Fe3O4 Magnetic Nanoparticles for the Synthesis of Oligopeptides in Organic Solvents

The use of nanobiocatalysts, with the combination of nanotechnology and biotechnology, is considered as an exciting and rapidly emerging area. The use of iron oxide magnetic nanoparticles, as enzyme immobilization carriers, has drawn great attention because of their unique properties, such as controllable particle size, large surface area, modifiable surface, and easy recovery. In this study, various γ‐Fe₂O₃/Fe₃O₄ magnetic nanoparticles with immobilized proteases were successfully prepared by three different immobilization strategies including A) direct binding, B) with thiophene as a linker, and C) with triazole as a linker. The oligopeptides syntheses catalyzed by these magnetic nanoparticles (MNPs) with immobilized proteases were systematically studied. Our results show that i) for magnetic nanoparticles immobilized α‐chymotrypsin, both immobilization strategies A and B furnished good reusability for the Z‐Tyr‐Gly‐Gly‐OEt synthesis, the MNPs enzymes can be readily used at least five times without significant loss of its catalytic performance: ii) In the case of Z‐Asp‐Phe‐OMe synthesis catalyzed by magnetic nanoparticles immobilized thermolysin, immobilization Strategy B provided the best recyclability: iii) For the immobilized papain, although Strategy A or B afforded an immobilized enzyme for the first cycle of Z‐Ala‐Leu‐NHNHPh synthesis in good yield, their subsequent catalytic activity decreased rapidly. In general, the γ‐Fe₂O₃ MNPs were better for use as an immobilization matrix, rather than the Fe₃O₄ MNPs, owing to their smaller particle size and higher surface area.     

Decoration of Fe3O4 nanoparticles on the surface of poly(acrylic acid) functionalized multi‐walled carbon nanotubes by covalent bonding

Fe₃O₄ nanoparticles were indirectly implanted onto functionalized multi‐walled carbon nanotubes (MWCNTs) leading to a nanocomposite with stronger magnetic performance. Poly(acrylic acid) (PAA) oligomer was first reacted with hydroxyl‐functionalized MWCNTs (MWCNTs‐OH) forming PAA‐grafted MWCNTs (PAA‐g‐MWCNTs). Subsequently, Fe₃O₄ nanoparticles were attached onto the surface of PAA‐g‐MWCNTs through an amidation reaction between the amino groups on the surface of Fe₃O₄ nanoparticles and the carboxyl groups of PAA. Fourier transform infrared spectra confirmed that the Fe₃O₄ nanoparticles and PAA‐g‐MWCNTs were indeed chemically linked. The morphology of the nanocomposites was characterized using transmission electron microscope (TEM). The surface and bulk structure of the nanocomposites were examined using X‐ray diffraction, X‐ray photoelectron spectrometer (XPS), and thermogravimetric analysis (TGA). The magnetic performance was characterized by vibrating sample magnetometer (VSM) and the magnetic saturation value of the magnetic nanocomposites was 47 emu g^?1. The resulting products could be separated from deionized water under an external magnetic field within about 15 s. Finally, the magnetorheological (MR) performances of the synthesized magnetic nanocomposites and pure Fe₃O₄ nanoparticles were examined using a rotational rheometer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Bacitracin‐Conjugated Superparamagnetic Iron Oxide Nanoparticles: Synthesis,Characterization and Antibacterial Activity

Bacitracin‐conjugated superparamagnetic iron oxide (Fe₃O₄) nanoparticles were prepared by click chemistry and their antibacterial activity was investigated. After functionalization with hydrophilic and biocompatible poly(acrylic acid), water‐soluble Fe₃O₄ nanoparticles were obtained. Propargylated Fe₃O₄ nanoparticles were then synthesized by carbodiimide reaction of propargylamine with the carboxyl groups on the surface of the iron oxide nanoparticles. By further reaction with N₃‐bacitracin in a Cu^I‐catalyzed azide–alkyne cycloaddition, the magnetic Fe₃O₄ nanoparticles were modified with the peptide bacitracin. The functionalized magnetic nanoparticles were characterized by powder X‐ray diffraction, X‐ray photoelectron spectroscopy, TEM, zeta‐potential analysis, FTIR spectroscopy and vibrating‐sample magnetometry. Cell cytotoxicity tests indicate that bacitracin‐conjugated Fe₃O₄ nanoparticles show very low cytotoxicity to human fibroblast cells, even at relatively high concentrations. In view of the antibacterial activity of bacitracin, the biofunctionalized Fe₃O₄ nanoparticles exhibit an antibacterial effect against both Gram‐positive and Gram‐negative organisms, which is even higher than that of bacitracin itself. The enhanced antibacterial activity of the magnetic nanocomposites allows the dosage and the side effects of the antibiotic to be reduced. Due to the antibacterial effect and magnetism, the bacitracin‐functionalized magnetic nanoparticles have potential application in magnetic‐targeting biomedical applications.     

Synthesis and Characterization of Iron Nanowires

The iron nanowires can be fabricated via the process in which sodium borohydride reduces iron salts in external magnetic field. The iron nanowires are found to be covered by passivated layers of iron oxide which prevent the oxidation of iron nanowires. In this process, the boron will include in iron nanowires. The average length and diameter of iron nanowires is around 1.2 micrometers and 60 nanometers, respectively. According to ICP results, the contents of B and Fe are about 1.98 wt% and 87.04 wt%, respectively, in iron nanowires. A wide variety of equipment is used to investigate the morphological, microchemical, and structural characteristics of the newly synthesized iron nanowires ––– e.g., XRD, FE‐SEM, HR‐TEM, VSM and XANES. XANES analysis indicates the boron in iron nanowires exists in the form of B₂O₃. The saturation magnetization and the coercive force of iron nanowires are 157.93 emu/g and 9.74 Oe, respectively. In‐situ images of synthesized iron nanowires during reduction process in magnetic field are observed by NSRRC transmission X‐ray microscope. Thus, this study develop a novel process to produce iron nanowires with large quantitates and can control its length and diameter by various the concentration of precursors for various applications.     

Effect of polyol structure on the properties of the resultant magnetic polyurethane elastomer nanocomposites

In this study, two types of magnetic polyurethane (PU) elastomer nanocomposites using polycaprolactone (PCL) and polytetramethylene glycol (PTMG) as polyols were synthesized by incorporating thiodiglycolic acid surface modified Fe₃O₄ nanoparticles (TSM‐Fe₃O₄) into PU matrices through in situ polymerization method. TSM‐Fe₃O₄ nanoparticles were prepared using in situ coprecipitation method in alkali media and were characterized by X‐ray diffraction, Fourier Transform Infrared Spectrophotometer, Transmission Electron Microscopy, and Vibrating Sample Magnetometer. The effects of PCL and PTMG polyols on the properties of the resultant PUs were studied. The morphology and dispersion of the nanoparticles in the magnetic nanocomposites were studied by Scanning Electron Microscope. It was observed that dispersion of nanoparticles in PTMG‐based magnetic nanocomposite was better than PCL‐based magnetic nanocomposite. Furthermore, the effect of polyol structure on thermal and mechanical properties of nanocomposite was investigated by Thermogravimetric Analysis and Dynamic Mechanical Thermal Analysis. A decrease in the thermal stability of magnetic nanocomposites was found compared to pure PUs. Furthermore, DMTA results showed that increase in glass transition temperature of PTMG‐based magnetic nanocomposite is higher than PCL‐based magnetic nanocomposite, which is attributed to better dispersion of TSM‐Fe₃O₄ nanoparticles in PTMG‐based PU matrix. Additionally, magnetic nanocomposites exhibited a lower level of hydrophilicity compared to pure PUs. These observations were attributed to the hydrophobic behavior of TSM‐Fe₃O₄ nanoparticles. Moreover, study of fibroblast cells interaction with magnetic nanocomposites showed that the products can be a good candidate for biomedical application. Copyright © 2013 John Wiley & Sons, Ltd.     

Cu (II)‐β‐cyclodextrin complex stabilized on magnetic nanoparticles: A retrievable hybrid promoter for green synthesis of spiropyrans

The magnetic core of manganese ferrite (MnFe₂O₄) nanoparticles has a significant stability in comparison with ferrite (Fe₃O₄) nanoparticles. The unique supramolecular properties of β‐cyclodextrin (β‐CD), such as hydrophobic cavity, hydrophilic exterior and ‐OH functional groups, make it a good candidate for functionalization and catalytic application. So, a surface‐modified magnetic solid support with the Cu (II)‐β‐CD complex was prepared. The structure of nanoparticles was characterized by Fourier transform‐infrared spectroscopy, X‐ray powder diffraction, thermogravimetric analysis, vibrating‐sample magnetometry, inductively coupled plasma‐optical emission spectrometry and scanning electron microscope analyses. The catalytic activity of these nanoparticles was investigated in the synthesis of spiropyrans and high yields of desired products obtained under green media. Some advantages of this novel catalyst for this reaction are high yields, short reaction times, green solvent and conditions, easy workup procedure, negligible copper leaching, reusability without a significant diminish in catalytic efficiency, and simple separation of nanocatalyst by using an external magnet alongside the environmental compatibility and sustainability.     

Controlled Synthesis of Fe3O4/ZIF‐8 Nanoparticles for Magnetically Separable Nanocatalysts

Fe₃O₄/ZIF‐8 nanoparticles were synthesized through a room‐temperature reaction between 2‐methylimidazolate and zinc nitrate in the presence of Fe₃O₄ nanocrystals. The particle size, surface charge, and magnetic loading can be conveniently controlled by the dosage of Zn(NO₃)₂ and Fe₃O₄ nanocrystals. The as‐prepared particles show both good thermal stability (stable to 550 °C) and large surface area (1174 m²g^?1). The nanoparticles also have a superparamagnetic response, so that they can strongly respond to an external field during magnetic separation and disperse back into the solution after withdrawal of the magnetic field. For the Knoevenagel reaction, which is catalyzed by alkaline active sites on external surface of catalyst, small Fe₃O₄/ZIF‐8 nanoparticles show a higher catalytic activity. At the same time, the nanocatalysts can be continuously used in multiple catalytic reactions through magnetic separation, activation, and redispersion with little loss of activity.     

Development of a New Label‐free,Indicator‐free Strategy toward Ultrasensitive Electrochemical DNA Biosensing Based on Fe3O4 Nanoparticles/Reduced Graphene Oxide Composite

Electrochemistry offers sensitivity, selectivity and low cost for fabrication of sensors capable of detection of selected DNA targets or mutated genes associated with human disease. In this work, we have developed a novel label‐free, indicator‐free strategy of electrochemical DNA sensor based on Fe₃O₄ nanoparticles/reduced graphene oxide (Fe₃O₄/r‐GO) nanocomposite modified electrode. By using Fe₃O₄/r‐GO nanocomposite as a substrate to immobilize probe DNA and subsequent hybridization with target sequence to form dsDNA, a great signal amplification was achieved through measuring changes in DPV peak current of underlying Fe(II)/Fe(III) redox system. With the remarkable attomolar sensitivity and high specificity and at the same time, great simplicity, the proposed strategy may find great applications in different DNA assay fields.     

Graphene‐Based Composite with γ‐Fe2O3 Nanoparticle for the High‐Performance Removal of Endocrine‐Disrupting Compounds from Water

Graphene is a 2D sp²‐hybridized carbon sheet and an ideal material for the adsorption‐based separation of organic pollutants. However, such potential applications of graphene are largely limited, owing to their poor solubility and extensive aggregation properties through graphene? graphene interactions. Herein, we report the synthesis of graphene‐based composites with γ‐Fe₂O₃ nanoparticle for the high‐performance removal of endocrine‐disrupting compounds (EDC) from water. The γ‐Fe₂O₃ nanoparticles partially inhibit these graphene? graphene interactions and offer water dispersibility of the composite without compromising much of the high surface area of graphene. In their dispersed form, the graphene component offers the efficient adsorption of EDC, whilst the magnetic iron‐oxide component offers easier magnetic separation of adsorbed EDC.     

Magnetic solid‐phase extraction based on a polydopamine‐coated Fe3O4 nanoparticles absorbent for the determination of bisphenol A,tetrabromobisphenol A, 2,4,6‐tribromophenol,and (S)‐1,1’‐bi‐2‐naphthol in environmental waters by HPLC

Polydopamine‐coated Fe₃O₄ magnetic nanoparticles synthesized through a facile solvothermal reaction and the self‐polymerization of dopamine have been employed as a magnetic solid‐phase extraction sorbent to enrich four phenolic compounds, bisphenol A, tetrabromobisphenol A, (S)‐1,1′‐bi‐2‐naphthol and 2,4,6‐tribromophenol, from environmental waters followed by high‐performance liquid chromatographic detection. Various parameters of the extraction were optimized, including the pH of the sample matrix, the amount of polydopamine‐coated Fe₃O₄ sorbent, the adsorption time, the enrichment factor of analytes, the elution solvent, and the reusability of the nanoparticles sorbent. The recoveries of these phenols in spiked water samples were 62.0–112.0% with relative standard deviations of 0.8–7.7%, indicating the good reliability of the magnetic solid‐phase extraction with high‐performance liquid chromatography method. In addition, the extraction characteristics of the magnetic polydopamine‐coated Fe₃O₄ nanoparticles were elucidated comprehensively. It is found that there are hydrophobic, π–π stacking and hydrogen bonding interactions between phenols and more dispersible polydopamine‐coated Fe₃O₄ in water, among which hydrophobic interaction dominates the magnetic solid‐phase extraction performance.     

The Synthesis of Magnetic Lysozyme‐Imprinted Polymers by Means of Distillation–Precipitation Polymerization for Selective Protein Enrichment

A protein imprinting approach for the synthesis of core–shell structure nanoparticles with a magnetic core and molecularly imprinted polymer (MIP) shell was developed using a simple distillation–precipitation polymerization method. In this work, Fe₃O₄ magnetic nanoparticles were first synthesized through a solvothermal method and then were conveniently surface‐modified with 3‐(methacryloyloxy)propyltrimethoxylsilane as anchor molecules to donate vinyl groups. Next a high‐density MIP shell was coated onto the surface of the magnetic nanoparticles by the copolymerization of functional monomer acrylamide (AAm), cross‐linking agent N,N′‐methylenebisacrylamide (MBA), the initiator azodiisobutyronitrile (AIBN), and protein in acetonitrile heated at reflux. The morphology, adsorption, and recognition properties of the magnetic molecularly imprinted nanoparticles were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), and rebinding experiments. The resulting MIP showed a high adsorption capacity (104.8 mg g^?1) and specific recognition (imprinting factor=7.6) to lysozyme (Lyz). The as‐prepared Fe₃O₄@Lyz‐MIP nanoparticles with a mean diameter of 320 nm were coated with an MIP shell that was 20 nm thick, which enabled Fe₃O₄@Lyz‐MIP to easily reach adsorption equilibrium. The high magnetization saturation (40.35 emu g^?1) endows the materials with the convenience of magnetic separation under an external magnetic field and allows them to be subsequently reused. Furthermore, Fe₃O₄@Lyz‐MIP could selectively extract a target protein from real egg‐white samples under an external magnetic field.     

Synthesis of Imatinib‐loaded chitosan‐modified magnetic nanoparticles as an anti‐cancer agent for pH responsive targeted drug delivery

Targeted drug delivery is a promising approach to overcome the limitations of classical chemotherapy. In this respect, Imatinib‐loaded chitosan‐modified magnetic nanoparticles were prepared as a pH sensitive system for targeted delivery of drug to tumor sites by applying a magnetic field. The proposed magnetic nanoparticles were prepared through modification of magnetic Fe₃O₄ nanoparticles with chitosan and Imatinib. The structural, morphological and physicochemical properties of the synthesized nanoparticles were determined by different analytical techniques including energy‐dispersive X‐ray spectroscopy (EDS), field emission scanning electron microscopy (FESEM), Fourier‐transform infrared (FTIR) spectroscopy, high resolution transmission electron microscopy (HR‐TEM), vibrating sample magnetometry (VSM), X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS). UV/visible spectrophotometry was used to measure the Imatinib contents. Thermal stability of the prepared particles was investigated and their efficiency of drug loading and release profile were evaluated. The results demonstrated that Fe₃O₄@CS acts as a pH responsive nanocarrier in releasing the loaded Imatinib molecules. Furthermore, the Fe₃O₄@CS/Imatinib nanoparticles displayed cytotoxic effect against MCF‐7 breast cancer cells. Results of this study can provide new insights in the development of pH responsive targeted drug delivery systems to overcome the side effects of conventional chemotherapy.     

Dispersive admicelle solid‐phase extraction based on sodium dodecyl sulfate coated Fe3O4 nanoparticles for the selective adsorption of three alkaloids in Gegen‐Qinlian oral liquid before high‐performance liquid chromatography

A novel dispersive admicelle solid‐phase extraction method based on sodium dodecyl sulfate‐coated Fe₃O₄ nanoparticles was developed for the selective adsorption of berberine, coptisine, and palmatine in Gegen‐Qinlian oral liquid before high‐performance liquid chromatography. Fe₃O₄ nanoparticles were synthesized by a chemical coprecipitation method and characterized by using transmission electron microscopy. Under acidic conditions, the surface of Fe₃O₄ nanoparticles was coated with sodium dodecyl sulfate to form a nano‐sized admicelle magnetic sorbent. Owing to electrostatic interaction, the alkaloids were adsorbed onto the oppositely charged admicelle magnetic nanoparticles. The quick separation of the analyte‐adsorbed nanoparticles from the sample solution was performed by using Nd‐Fe‐B magnet. Best extraction efficiency was achieved under the following conditions: 800 μL Fe₃O₄ nanoparticles suspension (20 mg/mL), 150 μL sodium dodecyl sulfate solution (10 mg/mL), pH 2, and vortexing time 2 min for the extraction of alkaloids from 10 mL of diluted sample. Four hundred microliters of methanol was used to desorb the alkaloids by vortexing for 1 min. Satisfactory extraction recoveries were obtained in the range of 85.9–120.3%, relative standard deviations for intra‐ and interday precisions were less than 6.3 and 10.0%, respectively. Finally, the established method was successfully applied to analyze the alkaloids in two batches of Gegen‐Qinlian oral liquids.