Core-shell Magnetic Nanoparticles Research Articles

A comparative analysis of antimicrobial agents in artificial saliva: Scoping review

Background: Artificial saliva should be formulated to mimic the physical properties and composition of the natural saliva. In addition to its moisturizing effects, artificial saliva should also include buffering and antimicrobial properties to adequately substitute the physiological functions of natural saliva. Most artificial saliva products focus on lubrication and moisture retention, with limited exploration of antimicrobial components. The optimal antimicrobial agents in artificial saliva have yet to be determined. Purpose: To identify antimicrobial agents used in artificial saliva. Methods: Article searches were conducted using the PRISMA flow chart in October 2024 using three databases: Scopus, Pubmed, and ScienceDirect. Selected articles were then evaluated for risk of bias using the JBI critical appraisal checklist. Results: Six quasi-experimental studies met the inclusion criteria and included in this review. Conclusion: Antimicrobial agents used in artificial saliva are xylitol, sorbitol, lysozyme, lactoferrin, lactoperoxidase with potassium thiocyanate, hinokitiol, protamine, whey protein, dried egg yolk, system of enzymes, fluoride ions, hydroxyethylcellulose, and core-shell magnetic nanoparticles. Various other active ingredients may also serve as antimicrobial agents.

Sensitive metal-enhanced photoluminescence and Raman scattering magnetic core–shell nano-particles with tunable size for the detection of methylene blue

The distance between the probe molecule and the metal nano-particle affects photoluminescence (PL) enhancement and surface-enhanced Raman scattering (SERS). On the one hand, magnetic Fe3O4 is introduced into the core–shell structure as a spacer, and the luminous molecules are separated from silver nano-particles (AgNPs) to prevent PL quenching. On the other hand, they are wrapped on the surface of AgNPs to weaken the effect of aggregation on Raman signals. Herein, magnetic core–shell nano-particles (Ag@Fe3O4) were successfully synthesised in one step; their size can be controlled by changing the added amount of Fe3+. In a series of experiments and comparisons, core–shell nano-particles that can be utilised for PL enhancement and SERS were obtained, and the enhancement factors of particles prepared in different batches were all above 20. In addition, the excellent time stability of Ag@Fe3O4 particles was confirmed, that is, the PL intensity only decreased by 8.6 % within 14 days. Therefore, the core–shell structure can detect methylene blue in aqueous solution by measuring emission spectrum, with a detection concentration as low as 0.1 μM.

Revolutionizing acridine synthesis: novel core-shell magnetic nanoparticles and Co-Zn zeolitic imidazolate framework with 1-aza-18-crown-6-ether-Ni catalysts

Nanoparticles have emerged as a critical catalyst substrate due to their exceptional features, such as catalytic efficiency, high stability, and easy recovery. In our research, we have developed an innovative and environmentally friendly magnetic mesoporous nanocatalyst. Using the co-precipitation method, we produced magnetic nanoparticles (Fe3O4) and coated them with Zeolitic imidazolate frameworks (ZIFs) to enhance their surface area and chemical stability. The resulting substrate was functionalized with 1-aza-18-crown-6-ether and nickel metal. Our prepared catalyst has been rigorously evaluated using advanced techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmet-Teller (BET), vibrating sample magnetometry (VSM), scanning electron microscopy and energy dispersive X-ray (SEM-EDS), inductively coupled plasma (ICP), elemental mapping analysis (EMA), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). By synthesizing acridine derivatives, we have demonstrated the exceptional efficiency of our catalyst in organic compound synthesis. Through optimization, we have established the ideal parameters for catalytic processes, including catalyst amount, temperature, time, and ultrasonic use. Our catalyst has been proven to exhibit remarkable physical and chemical properties, such as porosity, temperature resistance, and recyclability. Notably, our heterogeneous nanocatalyst has shown outstanding performance and can be recycled six times without any loss in efficiency, affirming its potential in acridine.

Porous polymeric materials prepared via pickering emulsion templating targeted as a bronsted acid catalyst in room-temperature biodiesel production

The present work is about preparing a set of magnetic macroporous polymers using the Pickering high internal phase w/o emulsions (HIPEs) templating method. The octyl-modified core-shell magnetic nanoparticles (Fe3O4@SiO2-Octyl) were used as a solid stabilizer and Span 80 surfactant to stabilize the HIPEs. The effect of Fe3O4@SiO2-Octyl content, Span 80 content, and molar ratio of styrene/divinylbenzene (St/DVB) on physical properties, morphology, pore size, and void size of the macroporous polyHIPEs was precisely evaluated. The optimized polyHIPE prepared by 2 wt% of Fe3O4@SiO2-Octyl nanoparticles, 9 wt% of Span 80, and St/DVB molar ratio of 8 with the porosity of 86±1.1 % and an average pore size of 4.1 µm was selected as catalyst support to functionalize with sulfonic acid groups. The resulting catalyst (polyHIPE–SO3H) showed excellent performance in reacting long-chain free fatty acids (FFA) with methanol to give fatty acid monoalkyl esters (FAMEs) at room temperature. In this way, the polyHIPE–SO3H was found to be very active and reusable in the mentioned process, giving high yields (∼92–98 %) of various biodiesel compounds under very mild reaction conditions and recycling in the next subsequent runs without significant loss of activity.

Highly sensitive detection of organophosphorus pesticides in water using a carboxyl-functionalized magnetic covalent organic framework

The development of novel methods for the precise quantification of organophosphate pesticides (OPPs), with enhanced accuracy, sensitivity, and efficiency, is crucial for environmental monitoring and human health risk assessment. In this study, Fe3O4@SiO2@COF-COOH magnetic core–shell nanoparticles were synthesized by coating a carboxyl-functionalized covalent organic framework (COF-COOH) onto the surface of amino-modified silica-coated iron(III) oxide particles (Fe3O4@SiO2-NH2). The incorporation of carboxyl groups, covalent organic framework and magnetic properties imparted superior performance to the adsorbent in magnetic solid-phase extraction (MSPE) of polar compounds from complex sample matrices. An analytical method based on Fe3O4@SiO2@COF-COOH coupled with GC–MS/MS was developed for the determination of eight organophosphate pesticide residues in river water near farmland. The established method displays good linearity in the range of 0.1–500 ng/mL for four OPPs and 1–2000 ng/mL for the other four, with correlation coefficients between 0.9903–0.9983. The LODs (S/N = 3) and LOQs (S/N = 10) were determined to be in the ranges of 0.53–9.6 ng/L and 1.8–31.9 ng/L, respectively. The adsorption mechanism was characterized by density functional theory calculations. Furthermore, the established method was successfully applied to analyze the distribution of trace OPPs in real river water samples collected from various cities in Henan Province. Its rapid, straightforward, and efficient ability to enrich trace levels of OPPs from complex real-world samples makes it a valuable tool for environmental monitoring, food safety, and human health management.

Investigating the effect of coating and synthesis parameters on La1-xSrxMnO3 based core-shell magnetic nanoparticles

Magnetic nanoparticles are an important class of functional materials that have unique magnetic properties due to their reduced size (<100 nm) and have the potential for use in many fields. In the preparation of magnetic nanoparticles, factors such as intrinsic magnetic properties, surface coating, size and shape of the particles, surface charge and stability are very important. In this regard, carefully determining the synthesis parameters of magnetic nanoparticles and particle coating materials is of critical importance in the application area chosen for the material. In this study, La1-xSrxMnO3 (x = 0.27, 0.30, 0.33) magnetic nanoparticles (MNPs), carbon-coated magnetic nanoparticles in core–shell structure (C@MNP) and their derivatives integrated into graphene oxide (GO-C@MNP) were synthesized and their properties were investigated in detail for their use in possible future application studies. The crystal structure of perovskite compounds with Pbnm symmetry remains unchanged after carbon coating but shrinks in volume due to its amorphous structure. The magnetic behavior of the uncoated and coated materials is almost identical, but the Curie temperature of the compounds shifts to a higher temperature. In the specific absorption ratio (SAR) measurements performed, it was found that the best SAR value for carbon-coated MNPs was 12.9 W/g at x = 0.27. By integrating the MNPs into graphene oxide, heat is easily distributed regionally, and this shows that the structures can be ideal candidates for applications such as hyperthermia, drug carriers, tissue repair, and cellular therapy including cell labeling and targeting.Perovskite-structured manganite materials were selected for their suitability in controlled production, where the Curie temperature can be tuned near the therapeutic temperature by adjusting the doping levels, making them ideal for magnetic hyperthermia applications. In this study, for the first time, the nanoparticle surfaces were coated with carbon, which was chosen not only due to carbon’s non-magnetic nature but also because it provides an ideal platform for future combined biomedical applications such as drug delivery systems.

Ferrocene-functionalized magnetic core-shell nanoparticles based on hydrosilylation reaction for pH-responsive doxorubicin delivery system

This study describes the development of an innovative pH-sensitive drug delivery system (DDS) utilizing ferrocene (Fc) and magnetic nanoparticles (MNPs) for cancer therapy. One potential method for generating a diverse range of functional NPs involves attaching functional substances to MNPs. In this investigation, we display the successful modification of Fe3O4 NPs by an Fc derivative (4-Ferrocenylbutyl)dimethylsilane through a hydrosilylation reaction toward the synthesis of the Fe3O4@SiO2@VTES@Fc nanocarrier (NC). The doxorubicin (DOX) drug was loaded onto Fe3O4@SiO2@VTES@Fc NC with a drug loading capacity of about 80 % via π-π stacking interactions. Also, the prepared materials were thoroughly characterized using FT-IR, XRD, FE-SEM, EDX-MAP, VSM, DAPI, MTT, antioxidants, and CV techniques. In vitro studies on the release of DOX from Fe3O4@SiO2@VTES@Fc NC indicated a pH-responsive behavior with a lower release rate (< 10 %) at pH 7.4 compared to pH 5 (approximately 70 %) over a period of 96 h. Moreover, cytotoxicity assessments demonstrated notable cytotoxic effects of DOX-loaded Fe3O4@SiO2@VTES@Fc on MCF-7 cells (IC50 value: ∼8 µg/mL). The study findings suggest that the fabricated magnetic core-shell NC (Fe3O4@SiO2@VTES@Fc/DOX) exhibits stimulus-responsive behavior and holds promise as a sophisticated approach to specifically transport therapeutic agents into tumor sites while minimizing exposure to healthy tissues.

A self-floating and windproof Janus biomass composite hydrogel with magnetic controllability and salt rejection for polluted seawater desalination

To alleviate the global freshwater crisis, a self-floating magnetic Janus biomass composite hydrogel has been fabricated through a rational asymmetric bilayer structure design, which exhibits many merits such as remarkable light-absorption, photothermal conversion, water-evaporation, salt rejection, wind-resistant, etc. Specifically, sodium alginate, cellulose nanofibrils (from corn straw), and acrylic acid were crosslinked by triple interpenetrating networks (chemical cross-linking, ionic cross-linking and hydrogen bonding). Janus hydrogel evaporator was constructed by incorporating the top layer containing light-absorbing core–shell magnetic nanoparticles (Fe3O4@PDA NPs), and the bottom layer composed of self-floating foam gel due to the addition of foaming agent. Under one solar irradiation, the average evaporation rate and photothermal conversion efficiency of Janus biomass composite hydrogel reached 2.89 ± 0.09 kg·m−2·h−1 and 95.66 ± 2.68 %, respectively. Its evaporation stability and salt tolerance capability have been demonstrated by extended period of simulated desalination. Furthermore, Janus biomass composite hydrogel also had excellent mechanical property (ultimate stress of 1.6 MPa) and magnetic performance, which can not only effectively resist the stress induced by wind and waves, but also enable the magnetic maneuvering and wind-resistance floating on the sea. When the input voltage of electromagnet was 24 V, the furtherest response displacement and maximum resisted wind speed were 9 cm and 7.2 m/s, respectively. Therefore, such magnetic self-floating Janus biomass composite hydrogel serving as interfacial solar-driven evaporator system offers a green, efficient and sustainable solution for clean freshwater production.

Efficient Adsorptive Removal of Cationic Dyes from Aqueous Solution by Magnetic Silica Core-Shell Nanoparticles

Efficient Adsorptive Removal of Cationic Dyes from Aqueous Solution by Magnetic Silica Core-Shell Nanoparticles

A comparative study of glutathione-coated iron oxide and glutathione-coated core-shell magnetic nanoparticles for their antiviral activities

A comparative study of glutathione-coated iron oxide and glutathione-coated core-shell magnetic nanoparticles for their antiviral activities

Anti-OTC antibody-conjugated fluorescent magnetic/silica and fluorescent hybrid silica nanoparticles for oxytetracycline detection

Abstract This study presents two alternative fluorescent nanoparticle-based oxytetracycline (OTC) detection methods in milk samples. Rhodamine 6G-coated fluorescent hybrid silica nanoparticles and fluorescent magnetic/silica nanoparticles functionalized with anti-OTC antibodies were used in this test. The sandwich test format was utilized to compare anti-OTC antibody-conjugated fluorescent magnetic/silica nanoparticles with OTC/OTC antibody-conjugated fluorescent hybrid silica nanoparticles in an Eppendorf tube with magnetic separators. The magnetic separator helps to quickly retain all of the OTC captured by fluorescent magnetic core–shell nanoparticles in the milk sample. As a result, the assay time was dramatically shortened. The obtained linear range was 1.34 × 10−6 to 2.10 × 10−8 (M) (R 2 = 0.9954), the detection limit was 4.76 ng/mL, and the total assay time was 90 min. This approach was used to determine the OTC concentration in milk samples, and the maximum percentage (%) of interference was less than 3.0%, with a recovery rate of greater than 97.0%. This approach offers a high potential for residue detection in milk samples. With a total analysis period of less than 90 min, this approach provided the best way to determine the capture and detector nanoparticles’ response.

Bi-magnetic Mn3O4@Ni core–shell binary superparticles: Self-assembly preparation and magnetic behaviors

Binary superparticles formed by self-assembling two different types of nanoparticles may utilize the synergistic interactions and create advanced multifunctional materials. Bi-magnetic superparticles with a core–shell structure have unique properties due to their specific spatial configurations. Herein, we built Mn3O4@Ni core–shell binary superparticles via an emulsion self-assembly technique. The superparticles are generated with a spherical morphology, and have a typical average size of about 240 nm. By altering the ratio of the two magnetic nanoparticles, the thickness of Ni shells can be adjusted. Oleic acid ligands are crucial for the formation of core–shell structure. Magnetic analysis suggests that core–shell superparticles display dual-phase magnetic interactions, contrasting with the single-phase magnetic behaviors of commonly core–shell magnetic nanoparticles. The calculation on the effective magnetic anisotropy constants indicates that the presence of Ni shell layers reduces the dipole interactions among the Mn3O4 core particles. Due to the presence of Ni nanoparticle shells, the blocking temperature of Mn3O4 is reduced, while the Curie temperature of Mn3O4 is independent on Ni content. Tunable magnetic properties can be achieved by modulating the Ni nanoparticle shell thickness. This study offers insights for the development of core–shell superparticles with varied magnetic characteristics.

Magnetic alginate core-shell nanoparticles based on Schiff-base imine bonding for pH-responsive doxorubicin delivery system

This research describes the development of a novel pH-responsive drug delivery system (DDS) based on sodium alginate (SA) and magnetic nanoparticles (MNPs) for cancer treatments. One possible approach to creating a wide variety of functional nanoparticles is to graft functional materials onto magnetite nanoparticles. In this study, we demonstrate the effective alteration of Fe3O4 nanoparticles using the alginate dialdehyde (ADA) group through a Schiff-Base imine reaction toward synthesizing Fe3O4@SiO2@APTMS@ADA (FSA@ADA) nanocarrier (NC). doxorubicin (DOX) as an anticancer drug was loaded (about 93 % drug loading capacities) on the FSA@ADA NC through chemical and physical interactions. doxorubicin (DOX) as an anticancer drug was loaded (about 93 % drug loading capacities) on the FSA@ADA NC through chemical and physical interactions. The synthesized nanocarriers were thoroughly characterized by various techniques, including FT-IR, FE-SEM, EDX-MAP, TEM, XRD, VSM, TGA, and 1HNMR. In vitro DOX release studies showed a pH-dependent manner and its release rate is lower (< 15 %) at 7.4 than pH 5 (about 75 %) over 25 days. Cytotoxicity results showed good biocompatibility for blank FSA@ADA (over about 85 % cell viability), whereas DOX-loaded FSA@ADA NCs had higher cytotoxic effects (IC50 value: ∼6 µg/mL) as a result of the controlled release of DOX into HeLa cells. Results showed that the magnetic core-shell FSA@ADA/DOX NC has the potential to be used as a targeted stimuli-responsive drug for cancer treatment.

Toxicity and magnetometry evaluation of the uptake of core-shell maghemite-silica nanoparticles by neuroblastoma cells.

Nanoparticle uptake by cells is a key parameter in their performance in biomedical applications. However, the use of quantitative, non-destructive techniques to obtain the amount of nanoparticles internalized by cells is still uncommon. We have studied the cellular uptake and the toxicity of core-shell maghemite-silica magnetic nanoparticles (MNPs), with a core diameter of 9 nm and a shell thickness of 3 nm. The internalization of the nanoparticles by mouse neuroblastoma 2a cells was evaluated by sensitive and non-destructive Superconducting Quantum Interference Device (SQUID) magnetometry and corroborated by graphite furnace atomic absorption spectroscopy. We were thus able to study the toxicity of the nanoparticles for well-quantified MNP uptake in terms of nanoparticle density within the cell. No significant variation in cell viability or growth rate was detected for any tested exposure. Yet, an increase in both the amount of mitochondrial superoxide and in the lysosomal activity was detected for the highest concentration (100 μg ml-1) and incubation time (24 h), suggesting the onset of a disruption in ROS homeostasis, which may lead to an impairment in antioxidant responses. Our results validate SQUID magnetometry as a sensitive technique to quantify MNP uptake and demonstrate the non-toxic nature of these core-shell MNPs under our culture conditions.

New 3D Vortex Microfluidic System Tested for Magnetic Core-Shell Fe3O4-SA Nanoparticle Synthesis.

This study's main objective was to fabricate an innovative three-dimensional microfluidic platform suitable for well-controlled chemical syntheses required for producing fine-tuned nanostructured materials. This work proposes using vortex mixing principles confined within a 3D multilayered microreactor to synthesize magnetic core-shell nanoparticles with tailored dimensions and polydispersity. The newly designed microfluidic platform allowed the simultaneous obtainment of Fe3O4 cores and their functionalization with a salicylic acid shell in a short reaction time and under a high flow rate. Synthesis optimization was also performed, employing the variation in the reagents ratio to highlight the concentration domains in which magnetite is mainly produced, the formation of nanoparticles with different diameters and low polydispersity, and the stability of colloidal dispersions in water. The obtained materials were further characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM), with the experimental results confirming the production of salicylic acid-functionalized iron oxide (Fe3O4-SA) nanoparticles adapted for different further applications.

Novel magnetic bimetallic AuCu catalyst for reduction of nitroarenes and degradation of organic dyes.

Herein, core-shell magnetic nanoparticles are modified with imidazolium-tagged phosphine and propylene glycol moieties and used for the stabilization of bimetallic AuCu nanoparticles. The structure and morphology of the prepared material are identified with SEM, TEM, XRD, XPS, atomic absorption spectroscopy, Fourier translation infrared spectroscopy, and a vibrating sample magnetometer. This hydrophilic magnetic bimetallic catalyst is applied in the reduction of toxic nitroarenes and reductive degradation of hazardous organic dyes such as methyl orange (MO), methyl red (MR), and rhodamine B (RhB), as well as in the degradation of tetracycline (TC). This magnetic AuCu catalyst indicated superior activity in all three mentioned reactions in comparison with its single metal Au and Cu analogs. This catalyst is recycled for 17 consecutive runs in the reduction of 4-nitrophenol to 4-aminophenol without a significant decrease in catalytic activity and recycled catalyst is characterized.

Enhancing biocatalyst performance through immobilization of lipase (Eversa® Transform 2.0) on hybrid amine-epoxy core-shell magnetic nanoparticles

Magnetic nanoparticles were functionalized with polyethylenimine (PEI) and activated with epoxy. This support was used to immobilize Lipase (Eversa® Transform 2.0) (EVS), optimization using the Taguchi method. XRF, SEM, TEM, XRD, FTIR, TGA, and VSM performed the characterizations. The optimal conditions were immobilization yield (I.Y.) of 95.04 ± 0.79 %, time of 15 h, ionic load of 95 mM, protein load of 5 mg/g, and temperature of 25 °C. The maximum loading capacity was 25 mg/g, and its stability in 60 days of storage showed a negligible loss of only 9.53 % of its activity. The biocatalyst demonstrated better stability at varying temperatures than free EVS, maintaining 28 % of its activity at 70 °C. It was feasible to esterify free fatty acids (FFA) from babassu oil with the best reaction of 97.91 % and ten cycles having an efficiency above 50 %. The esterification of produced biolubricant was confirmed by NMR, and it displayed kinematic viscosity and density of 6.052 mm2/s and 0.832 g/cm3, respectively, at 40 °C. The in-silico study showed a binding affinity of −5.8 kcal/mol between EVS and oleic acid, suggesting a stable substrate-lipase combination suitable for esterification.

Development of magnetic La doped Al2O3 core-shell nanoparticle loaded hydrogel for selective recovery of fluoride from aquatic medium

The selective removal of pollutants from water bodies is regarded as a conciliation between the rapid expansion of industrial activities and need of clean water for sustainability. Fluoride is one such geogenic pollutant, and various materials have already been reported. Developing an efficient field employable material is however a challenge. Herein, we report the synthesis and competencies of strategically designed magnetic La-doped Al2O3 core-shell nanoparticle loaded polymeric nanohybrid as a benchmark fluoride sorbent. A facile synthesis strategy involved fabrication of Fe3O4 magnetic core followed by growth of La doped Al2O3 shell using sol-gel method. Doping of La2O3 into Al2O3 structure was optimised (6%), resulting in Fe3O4-Al0.94 La0.06O1.5 core-shell particles which provided exceptional fluoride affinity. The obtained magnetic Fe3O4-Al0.94La0.06O1.5 core-shell nanoparticles were then loaded (22%) into alginate to form cross-linked hydrogel beads (Fe3O4-Al0.94 La0.06 O1.5-Ca-ALG). These prepared hydrogel beads were characterised and utilized for selective recovery of fluoride under different ambient conditions. Driving forces for enhanced fluoride uptake by La doped Al2O3 were investigated and explained with the help of both experimental observation and theoretical simulation. Density functional theory calculations indicated significant expansion in the cell volume of Al2O3 due to La doping which favoured the fluoride sorption. The calculated defect formation energy for the incorporation of F into Al2O3 was found to decrease in the presence of La. XPS analysis suggested direct interaction of fluoride with Al, forming Al-F bond and breaking Al-O bond. Different vital parameters for uptake were optimised. Also, kinetics, isotherm and diffusion models were evaluated. Developed hydrogel beads attained record sorption capacity of 132.3mgg-1 for fluoride. Overall, excellent stability, no leaching of constituents, effectiveness for selective fluoride recovery from groundwater, brand it a perfect epitome of sustainable water treatment application.

Production and immobilization of pectinases from Penicillium crustosum in magnetic core-shell nanostructures for juice clarification

Global market of food enzymes is held by pectinases, mostly sourced from filamentous fungi via submerged fermentation. Given the one-time use nature of enzymes to clarify juices and wines, there is a crucial need to explore alternatives for enzyme immobilization, enabling their reuse in food applications. In this research, an isolated fungal strain (Penicillium crustosum OR889307) was evaluated as a new potential pectinase producer in submerged fermentation. Additionally, the enzyme was immobilized in magnetic core-shell nanostructures for juice clarification. Findings revealed that Penicillium crustosum exhibited enzymatic activities higher than other Penicillium species, and pectinase production was enhanced with lemon peel as a cosubstrate in submerged fermentation. The enzyme production (548.93 U/mL) was optimized by response surface methodology, determining the optimal conditions at 35 °C and pH 6.0. Subsequently, the enzyme was covalently immobilized on synthesized magnetic core-shell nanoparticles. The immobilized enzyme exhibited superior stability at higher temperatures (50 °C) and acidic conditions (pH 4.5). Finally, the immobilized pectinases decreased 30 % the orange juice turbidity and maintained 84 % of the enzymatic activity after five consecutive cycles. In conclusion, Penicillium crustosum is a proven pectinase producer and these enzymes immobilized on functionalized nanoparticles improve the stability and reusability of pectinase for juice clarification.

Quantitative detection of chloramphenicol residue in fish based on SERS aptasensor coupled with magnetic separation

Chloramphenicol (CAP) is a widely used antibiotic in aquaculture. However, its improper use and the resulting residues in fish have become a significant concern for human health. Conventional methods for quantifying CAP are complex and expensive, leading to the need for more efficient and sensitive techniques. In this study, both CAP aptamer and sulfhydryl (SH) complementary DNA strand (SH-cDNA) were bound to gold and silver core–shell nanoparticles (Ag@Au CSNPs) and core–shell magnetic nanoparticles (Fe3O4@Au MNPs) via Au-S covalent bonding and were used as SERS signal probes and capture probes, respectively. The principle of aptamer competitive recognition was applied to achieve the quantitative detection of CAP in fish. The capture probe and the signal probe generated strong signals by complementary hybridization in the absence of CAP in the detection system. In the presence of CAP, the CAP aptamer bonded to the CAP, and the signal probe was separated from the capture probe, resulting in a linear decrease in SERS signal intensity. Consequently, there was a strong inverse relationship between SERS intensity and the logarithm of CAP concentration, ranging from 10-5 to 10-1 µg·mL−1 (R2 = 0.9974). The limit of detection (LOD) was as low as 16 pg·mL−1. The established method exhibited strong selectivity, anti-interference, reproducibility, and stability.