Detection Of Aflatoxin B1 Research Articles

A toluidine blue/porous organic polymer/2D MoSe2 nanocomposite as an electrochemical signaling platform for a sensitive label-free aflatoxin B1 bioassay in some crops

A label-free electrochemical immunosensor using a toluidine blue (TB)/porous organic polymer (POP)/two-dimensional molybdenum diselenide (2D MoSe2) nanocomposite is developed for highly sensitive detection of aflatoxin B1 (AFB1) in selected crops. A POP/2D MoSe2 composite material is employed to modify the surface of a screen-printed carbon electrode (SPCE). Subsequently, TB is adsorbed on the modified SPCE surface, and the resulting TB/POP/2D MoSe2 composite is then used to construct a biosensor. The new POP/2D MoSe2 nanocomposite offers a high surface-to-volume area and is a good electroactive and biocompatible adsorbent for loading TB probe and capture antibodies. Adsorbed TB onto the POP/2D MoSe2 nanocomposite is utilized as a redox probe for the signal amplification unit. This TB/POP/2D MoSe2 nanocomposite provides good electron transfer properties of TB redox probe, good electrical conductivity, good biocompatibility, and likable adsorption ability, thus obtaining a sufficient immobilization quantity of antibodies for the sensor construction. After immobilization of the anti-AFB1 antibody and blocking with BSA on the composite surface, the immunosensor is obtained for the detection of AFB1. Under optimum conditions, the sensor shows a linear logarithmic range of 2.5–40 ng mL−1 with a limit of detection (LOD) of 0.40 ng mL−1. The developed sensor provides several advantages in terms of simplicity, low cost, short analysis time, high selectivity, stability, and reproducibility. Additionally, the proposed immunosensor is successfully validated by the detection of AFB1 in rice, corn, and peanut samples. Utilizing the TB/POP/2D MoSe2 nanocomposite, this label-free electrochemical immunosensor demonstrates outstanding sensitivity and selectivity in detecting AFB1, making it a valuable tool for ensuring the safety of agricultural products and enhancing food security.

Simultaneous detection of AFB1 and aflD gene by "Y" shaped aptamer fluorescent biosensor based on double quantum dots.

The developed method for simultaneous detection of aflatoxin B1 (AFB1) and aflD genes can effectively monitor from the source and reduce the safety problems and economic losses caused by the production of aflatoxin, which can be of great significance for food safety regulations. In this paper, we constructed a sensitive and convenient fluorescent biosensor to detect AFB1 and aflD genes simultaneously based on fluorescence resonance energy transfer (FRET) between quantum dots (QDs) and a black hole quenching agent. A stable "Y" shaped aptasensor was employed as the detection platform and a double quantum dot labeled DNA fragment was utilized to be the sensing element in this work. When the targets of AFB1 and aflD genes were presented in the solution, the aptamer in the "Y" shaped probe is specifically recognized by the target. At this time, both Si-carbon quantum dots (Si-CDs) and CdTe QDs are far away from the BHQ1 and BHQ3 to recover the fluorescence. The linear range of the prepared fluorescence simultaneous detection method was as wide as 0.5-500ng·mL-1 with detection lines of 0.64ng·mL-1 for AFB1 and 0.5-500nM with detection lines of 0.75nM for aflD genes (3σ/k). This fabricated fluorescent biosensor was further validated in real rice flour and corn flour samples, which also achieved good results. The recoveries were calculated by comparing the known and found amounts of AFB1 which ranged from 88.4 to approximately 115.32% in the rice flour samples and 90.7 ~ 102.58% in the corn flour samples. The recoveries of aflD genes ranged from 84.32 to approximately 109.3% in the rice flour samples and 89.48 ~ 100.99% in the corn flour samples. Therefore, the proposed biosensor can significantly improve food safety and quality control through a simple, fast, and sensitive agricultural product monitoring and detection system.

A versatile CuCo@PDA nanozyme-based aptamer-mediated lateral flow assay for highly sensitive, on-site and dual-readout detection of Aflatoxin B1

Mycotoxin contaminations in food and environment seriously harms human health. Constructing sensitive and point-of-test early-warning tools for mycotoxin determination is in high demand. In this study, a CuCo@PDA nanozyme-based aptamer-mediated lateral flow assay (Apt-LFA) has been elaborately designed for on-site and sensitive determination of mycotoxin Aflatoxin B1 (AFB1). Benefiting from the rich functional groups and excellent peroxidase-like activity, the CuCo@PDA with original dark color can be conjugated with the specific recognition probe (i.e., aptamer), generating colorimetric signal on the test lines of Apt-LFA via a competitive sensing strategy. The signal can further be amplified in-situ by catalytic chromogenic reaction. Therefore, a visual and dual-readout detection of AFB1 has been realized. The developed Apt-LFA provides a flexible detection mode for qualitative and quantitative analysis of AFB1 by naked-eyes observation or smartphone readout. The smartphone-based LFA platform shows a reliable and ultrasensitive determination of AFB1 with the limit of detection (LOD) of 2.2 pg/mL. The recoveries in the real samples are in the range of 95.11–113.77% with coefficients of variations less than 9.84%. This study provides a new approach to realize point-of-test and sensitive detection of mycotoxins in food and environment using nanozyme-based Apt-LFAs.

Self-assembled programmable DNA nanoflower for in situ synthesis of gold nanoclusters and integration with Mn-MOF to sensitively detect AFB1

Aflatoxin B1 (AFB1) is a potent carcinogenic mycotoxin that is susceptible to contamination of agricultural products and can cause chronic effects on humans. Thus, the establishment of highly sensitive and efficient AFB1 detection method is crucial to ensure food safety and human health. Here, we developed programmable DNA nanoflowers (DNF) with dual functionality for in situ synthesis of gold nanoclusters (AuNCs) and DNA recognition. The AuNCs synthesized using DNF as template (DNF@AuNCs) possessed good fluorescence properties and stability, and were applied as stable signal probes for constructing sensitive aptasensor. DNF completed the transition from bud to blooming flower, shifting its morphology from 3D to 2D structure during the in-situ synthesis of AuNCs, leading to the exposure of more template sequences. The designed hairpins DNA were subsequently used for local catalytic hairpin assembly (LCHA) on the surface of Mn-MOF. A substantial number of amplified products H2-H3 was obtained by conformational conversion, which was complementary to the sequence of DNF. Upon hybridization of H2-H3 with DNF@AuNCs, the fluorescence of AuNCs is quenched by adjacent guanine-rich (G-rich) base at the 3′ end of H3. The switch of LCHA is controlled by the conformational change of H1 which contains the AFB1 aptamer sequence, thus enabling precise detection of AFB1. The DNF@AuNCs and Mn-MOF-based fluorescence aptasensor achieved a detection limit of 7 pg/mL for AFB1, with a detection range of 0.01–200 ng/mL. The aptasensor also exhibits high selectivity, reproducibility, and stability, making it prospective for food safety monitoring.

Ratiometric fluorescence and absorbance dual-model immunoassay based on 2,3-diaminophenazine and carbon dots for detecting Aflatoxin B1

In this work, a dual-model immunoassay for detecting Aflatoxin B1 (AFB1) was developed based on 2,3-diaminophenazine (DAP) and carbon dots (CDs). Under the catalysis of horseradish peroxidase (HRP), the o-phthalylenediamine (OPD) was oxidized to DAP which had a yellow color and intense fluorescence. The color changes form colorless to yellow was used to design absorbance model immunoassay. Meanwhile, the absorption spectrum of DAP overlapped with the emission spectrum of CDs which caused the fluorescence of CDs to be quenched. The fluorescence changes of DAP and CDs were used to develop ratiometric fluorescence immunoassay. The dual-model immunoassay showed excellent sensitivity with the limits of detection (LODs) of 0.013 ng/mL for fluorescence mode and 0.062 ng/mL for absorbance mode. Meanwhile, both models exhibited great selectivity for AFB1. Additionally, the recovery rates suggested the proposed dual-model immunoassay had great potential in actual samples detection.

A Label-Free Aptasensor for Turn-On Fluorescent Detection of Aflatoxin B1 Based on an Aggregation-Induced-Emission-Active Probe and Single-Walled Carbon Nanohorns.

The determination of the aflatoxin B1 (AFB1) content has received widespread attention in the context of food safety, which is a global public health issue. Accordingly, a label-free and turn-on fluorescent AFB1 determination method is developed herein with an ss-DNA aptamer as the recognition element, 4, 4-(1E,1E)-2, 2-(anthracene-9, 10-diyl) bis(ethene-2, 1-diyl) bis(N, N, N-trimethylbenzenaminium iodide) (DSAI) as the aggregation-induced emission (AIE) fluorescent probe, and single-walled carbon nanohorns (SWCNHs) as the selective part with a fluorescence quenching effect. In the presence of AFB1, the AFB1-specific aptamer undergoes a structural transformation and switches from being a random helix to a folded structure. DSAI's fluorescence is protected as a result of the resistance of the transformed aptamer adsorbed on the SWCNHs' surface. Because DSAI's fluorescence is not quenchable, the fluorescence intensity is calculated as a function of the AFB1 concentration. By simply mixing DSAI, aptamer, AFB1 samples, and SWCNHs, the method can be carried out in 2 h, with a limit of detection (LOD) of 1.83 ng/mL. It has a high selectivity in the presence of other mycotoxins, and its performance is confirmed in soybean sauce with a known concentration of AFB1. The LOD was 1.92 ng/mL in the soy sauce samples and the recovery ranged from 95 to 106%, implying that the presented aptasensor has great potential for food analysis.

A Fluorescence Resonance Energy Transfer Aptasensor for Aflatoxin B1 Based on Ligand-Induced ssDNA Displacement

In this study, a fluorescence resonance energy transfer (FRET)-based aptasensor for the detection of aflatoxin B1 (AFB1) was designed using a carboxyfluorescein (FAM)-labeled aptamer and short complementary DNA (cDNA) labeled with low molecular quencher RTQ1. The sensing principle was based on the detection of restored FAM-aptamer fluorescence due to the ligand-induced displacement of cDNA in the presence of AFB1, leading to the destruction of the aptamer/cDNA duplex and preventing the convergence of FAM and RTQ1 at the effective FRET distance. Under optimal sensing conditions, a linear correlation was obtained between the fluorescence intensity of the FAM-aptamer and the AFB1 concentration in the range of 2.5–208.3 ng/mL with the detection limit of the assay equal to 0.2 ng/mL. The assay time was 30 min. The proposed FRET aptasensor has been successfully validated by analyzing white wine and corn flour samples, with recovery ranging from 76.7% to 91.9% and 84.0% to 86.5%, respectively. This work demonstrates the possibilities of labeled cDNA as an effective and easily accessible tool for sensitive AFB1 detection. The homogeneous FRET aptasensor is an appropriate choice for contaminant screening in complex matrices.

UiOL@AIEgens-assisted lateral flow immunosensor for the ultrasensitive dual-modal point-of-care detection of aflatoxin B1

Aflatoxin B1 (AFB1) contamination in food has attracted worldwide attention. The sensitive detection of AFB1 is vital for ensuring food quality and safety. This study developed an ultrasensitive signal-enhanced lateral flow immunosensor (LFIS) based on the functionalized zirconium metal-organic framework (MOF) of a UiO linker enriched with abundant aggregation-induced emission luminogen (UiOL@AIEgens) probes for the rapid dual-modal point-of-care (POC) determination of AFB1. Using UiO MOFs with numerous active sites as the carrier facilitated abundant AIEgens enrichment on the surface. After coupling with enough anti-AFB1 monoclonal antibodies (mAbs), the green-emissive UiOL@AIEgens-mAbs probes with high specificity and remarkably-enhanced fluorescence responses were obtained to competitively capture target AFB1 in the standard or sample solution and AFB1 antigen immobilized on the test (T) line of the POC LFIS. Under optimum conditions, the LFIS was capable of visual qualitative and smartphone-assisted dual-modal determination of target AFB1 within 7 min. Detection occurred in a range of 0.01–5 ng/mL at an ultra-low detection limit of 0.003 ng/mL, which was 300- and 600-fold lower than traditional immunoassays and the maximum limit set by the European Union, respectively. Moreover, the feasibility and robustness of the LFIS platform were assessed by detecting AFB1 in maize and lotus seed samples with average recoveries of 94.3–109.0%. The developed UiOL@AIEgens-based POC LFIS can be used for ultrasensitive, reliable, on-site detection in food. This study provides a new method for the real-time monitoring of AFB1 and other harmful contaminants in food and more complex matrices.

Multiple Isothermal Amplification Coupled with CRISPR-Cas14a for the Naked-eye and Colorimetric Detection of Aflatoxin B1.

Aflatoxin B1 (AFB1) is highly toxic and challenging to remove, posing significant risks to both human health and economic development. Therefore, there is an urgent need to develop rapid, simple, and sensitive detection technologies. In this study, we introduce a naked-eye and colorimetric method based on multiple isothermal amplifications coupled with CRISPR-Cas14a and investigate its biosensing properties. This technique utilizes composite nanoprobes (MAPs) comprising magnetic nanoparticles and gold nanoparticles. AFB1 is efficiently identified through an aptamer competition process facilitated by magnetic nanoparticles , which triggers multiple isothermal amplification. This converts trace amounts of the toxin into a large quantity of DNA signal. Upon specific activation of the CRISPR-Cas14a complex, the MAPs are cleaved, resulting in significant changes in both color and colorimetric signal. The method demonstrates acceptable sensitivity, with a detection limit of 31.90 pg mL-1 and a wide detection range from 0.05 to 10 ng mL-1. Furthermore, the assay exhibits satisfactory specificity and high accuracy when it is applied to practical samples. Our approach offers a universal sensing platform with potential applications in food safety, environmental monitoring, and clinical diagnostics.

Study on CdSe/ZnS Quantum Dot Fluorescence Immunoprobe for Detection of Aflatoxin B1 in 5 Traditional Chinese Medicines.

Aflatoxin is a highly toxic substance, of which aflatoxin B1 is the most toxic and carcinogenic among aflatoxins. In this paper, the team used homemade CdSe/Zns quantum dots to construct a fluorescent immunoprobe and all-antigen coupling with aflatoxin B1. It used a self-developed fluorescence intensity detector to detect aflatoxin B1 in five traditional Chinese medicines, namely, ginseng, Panax ginseng, Chuanxiong rhizome, rhubarb, and yam. The recoveries were 80.0-102.0%; the relative standard deviations (RSD)were from 2.4 to 9.2.

Nitrogen-doped carbon dot and DNA tetrahedron nanostructure based electrochemiluminescence aptasensor for AFB1 detection

An electrochemiluminescence (ECL) aptasensor with aptamer as recognition element, N-doped carbon dots (N-CDs) as luminophore, and DNA tetrahedral nanostructure (DTN) as carrier to loading abundant N-CDs for signal amplification was developed for ultra-sensitive aflatoxin B1 (AFB1) detection. The complementary DNA (cDNA) was firstly immobilized on the Au electrode (AuE) surface to hybridize with the AFB1 aptamer. In the presence of AFB1, it would competitively with cDNA for binding the aptamer, causing the exposure of cDNA. DTN modified with AFB1 aptamer on top and N-CDs on the four vertices would combine with cDNA onto the AuE surface to generate ECL signals due to electron transfer between co-reactants (K2S2O8) and N-CDs, which was positively related to the concentration of AFB1. Due to the high specificity of aptamer, the outstanding ECL performance of N-CDs and the enhanced signal output of DTN/N-CDs probes, the as-constructed ECL aptasensor realized excellent sensitivity with a low detection limit of 77 pg/mL and a wide linear concentration of 1.0 × 10−1-1.0 × 104 ng/mL for AFB1, as well as fascinating accuracy with acceptable recoveries of 89.54–111.0% in the spiked Coix seed matrices. Successful application for AFB1 detection in actual samples confirmed the extensive practicability of the ECL aptasensor, providing a universal platform for more trace contaminants by altering the corresponding aptamers.

Electrohydrodynamic-printed ultrathin Ti3C2Tx-MXene field-effect transistor for probing aflatoxin B1

Microarray patterns fabricated using printing technology have attracted significant research interest for the production of portable, implantable, feasible, wearable, and flexible electronics. Electrohydrodynamic (EHD) printing is an emerging, simple, and rapid electrode-patterning technology for academic and industrial applications. The development of devices composed of MXenes, 2D hexagonal crystals, which demonstrate great potential for electronic and energy storage applications, is one of the main focuses of current research efforts. Herein, we report the EHD-printed Ti3C2Tx MXene-based field-effect transistors (FET) as promising biosensors for aflatoxin B1 (AFB1) detection. The printing cycles and ink concentration were considered as the optimization objectives, and the optimized FET was validated using the output and transfer characteristics of the device. The optimized EHD-printed FET exhibited good adhesion to the substrate, high electrical conductivity, and an ideal range of resistance. The biosensor was created by functionalizing the EHD-printed MXene layers with a specific antibody against AFB1. This FET biosensor could detect the AFB1 at a concentration of 0.01 ppb with a linearity range of 0.7–20 ppb in a water medium (limit of detection = 5.689 ppb). In addition, the FET biosensor successfully detected AFB1 in food samples, such as peanut butter and meju. Thus, we have successfully demonstrated a promising EHD-printed FET biosensor for AFB1. The device is a highly selective and sensitive immunoanalytical method for AFB1 that requires no complex sample preparation steps compared with high-performance liquid chromatography.

Quantitative SERS detection of aflatoxin B1 in edible crude palm oil using QuEChERS combined with chemometrics

Aflatoxin B1 (AFB1) is a potent carcinogen whose presence in food threatens consumers. This study aimed to develop a rapid method for the quantitative detection of AFB1 in crude palm oil (CPO) using novel gold nanoparticles (AuNPs) and the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) technique, combined with chemometrics. The bootstrapping soft shrinkage-partial least squares (BOSS-PLS) algorithm yielded the most favorable results, with an Rc of 0.9929, RMSECV of 0.204 ng/g, and an RPD of 3.93. The results demonstrated that the developed method is highly accurate, sensitive, and specific for detecting AFB1 in CPO, with a low limit of detection (LOD) of 0.00092 ng/g. The results underscore the potential of employing a combination of AuNPs, QuEChERS extraction, and chemometrics for detecting AFB1 in CPO. The developed method can be employed to monitor and ensure the quality of CPO, thereby preventing the spread of AFB1 contamination in the food industry.

A Dynamic and Pseudo-Homogeneous MBs-icELISA for the Early Detection of Aflatoxin B1 in Food and Feed.

Aflatoxin B1 (AFB1) is one of the most toxic and harmful fungal toxins to humans and animals, and the fundamental way to prevent its entry into humans is to detect its presence in advance. In this paper, the monoclonal antibody mAbA2-2 was obtained via three-step sample amplification and multi-concentration standard detection using a subcloning method based on the limited dilution method with AFB1 as the target. A dynamic and pseucdo-homogeneous magnetic beads enzyme-linked immunosorbent assay (MBs-icELISA) was established using the prepared antibody as the recognition element and immunomagnetic beads as the antigen carrier. The MBs-icELISA showed good linear correlation in the concentration range of 0.004-10 ng/mL with R2 = 0.99396. The limit of detection (LOD) of the MBs-icELISA for AFB1 was 0.0013 ng/mL. This new ELISA strategy significantly shortened AFB1 detection time through improved sensitivity compared to the conventional ELISA method.

A novel Recjf Exo signal amplification strategy based on bioinformatics-assisted truncated aptamer for efficient fluorescence detection of AFB1

Aflatoxin B1 (AFB1) is a typical mycotoxin that signifacntly endangers public health and economy. In this study, we systematically studied the interaction of aptamers with AFB1 using circular dichroism, molecular dynamics, molecular docking, and fluorescence analysis. The truncated sequence aptamers were screened using molecular docking. We successfully obtained the AFB1 aptamer with higher affinity and its truncated form was enhanced by 5.2-fold compared to the initial AFB1 aptamer. In addition, for rapid detection of AFB1, we designed a fluorescent nano-adaptor sensing platform using RecJf exonuclease signal amplification strategy based on the optimal aptamer. The aptasensor showed satisfactory sensitivity towards AFB1 with a linear detection range of 1–400 ng/mL and a detection limit of 0.57 ng/mL. The aptasensor was successfully applied to the determination of AFB1 in soybean oil and corn oil with recoveries of 91.02 %–106.59 % and 87.39 %–110.61 %, respectively. The successful application of the AFB1 aptasensor, developed through bioinformatics truncation of the aptamer, provides a novel approach to creating a cost-effective, eco-friendly, and rapid aptamer sensing platform.

A novel MB-tagged aptasensor for Aflatoxin B1 detection in food using Fe3O4 nanoparticles substantiated with in silico modelling

Aspergillus fungi species found in wheat, maize, rice, and other agricultural products produce the carcinogenic mycotoxin known as Aflatoxin B1 (AFB1), which can cause cancer in animals and humans. Consequently, recent interest has surged regarding the need for inexpensive, selective, and sensitive sensors to detect AFB1 in food. An ultrasensitive electrochemical aptasensor for AFB1 analysis was constructed using carboxylated multiwalled carbon nanotubes (cMWCNTs) and iron oxide (Fe3O4) nanoparticles (NP) on a glassy carbon electrode (GCE). The peptide bond formation by EDC coupling between the aptamer and cMWCNTs-Fe3O4 NP composite exhibited a strong anodic redox response from AFB1 using cyclic voltammetry (CV) in this study. Applying differential pulse voltammetry (DPV), the GCE/cMWCNTs-Fe3O4 NP aptasensor exhibited very low limits of detection (LOD) and quantification (LOQ) of 0.43 fg mL−1 and 1.44 fg mL−1 respectively over a calibration ranging from 0.50 fg mL−1 to 5.00 fg mL−1. For actual sample analysis, excellent spike recoveries from 95 to 105% were obtained for corn and rice flour. Single particle ICP-MS (spICP-MS) confirmed the average mass-based diameter of the synthesized Fe3O4 NPs to be in the nano-range (d ≈ 20 nm), the properties of which are essential for the facilitation of strong electron transfer in DPV sensing. Finally, density functional theory and molecular docking studies predicted the sensing mechanism and supported deductions based on the AFB1 capture by the employed aptamer respectively. As part of South Africa’s quality control and regulatory frameworks, this study aims to contribute toward the prevention of AFB1 exposure in foods.

Target-Induced Electrochemical Sensor Based on Foldable Aptamer and MoS2@MWCNTs-PEI for Enhanced Detection of AFB1 in Peanuts.

Herein, a sensitive and selective electrochemical sensor based on aptamer folding was constructed to detect aflatoxin B1 (AFB1) in peanuts. Specifically, polyethylenimine-functionalized multiwalled carbon nanotubes modified with molybdenum disulfide (MoS2@MWCNTs-PEI) were used as the electrode matrix to enable a large specific surface area, which were characterized by the Randles-Sevcik equation. Additionally, AuNPs were used to immobilize the aptamer via the Au-S covalent bond and provide a favorable microenvironment for signal enhancement. Methylene blue (MB) was modified at the proximal 3' termini of the aptamer as the capture probe, while the signal transduction of the sensor was obtained through changes in conformation and position of MB induced by the binding between AFB1 and the probe. Changes in spatial conformation could be recorded by electrochemical methods more readily. This electrochemical aptasensor demonstrated remarkable sensitivity to AFB1 with an extensive detection range (1 pg/mL to 100 ng/mL) and a lower limit detection (1.0 × 10-3 ng/mL). Moreover, using the constructed aptasensor, AFB1 was identified successfully in peanut samples, with recoveries ranging from 95.83 to 107.53%, illustrating its potential use in determining AFB1 in food.

3D plasmonic SERS aptasensor for rapid detection of aflatoxin B1 combined with Au@Ag bimetallic nanostars and Fe3O4@MoS2 magnetic nanoflowers

As a virulent metabolite, aflatoxin B1 (AFB1) presented in various cereal grain is tightly implicated in severe human diseases. In this study, 3D plasmonic nanohybirds of Raman molecule 4-mercaptobenzoic acid (4-MBA)-embedded and AFB1 aptamer-modified bimetallic nanostars as SERS probes bound to magnetic nanoflowers were fabricated and demonstrated as a high-performance SERS-active aptasensor to quantitatively analyze AFB1. Bimetallic Au@Ag SERS plasmonic nanoprobes with enhanced properties were capable of enhancing discriminative Raman peaks of 4-MBA. Then, the integration of iron tetroxide nanoparticles (Fe3O4 NPs) and molybdenum disulfide nanosheets (MoS2 NShs) with huge specific surface area constituted stable 3D Fe3O4@MoS2 plasmonic nanoflowers, facilitating the bind of numerous aptamer-based SERS probes via the non-covalent interaction between MoS2 NShs and aptamer, which were ideal candidates for SERS-active substrates. Additionally, Fe3O4 NPs as magnetic core endowed 3D nanocomposites with specific magnetic separation characteristic that caused the collected SERS hotspots to exhibit superior signal response, and further strengthening the sensitivity in a complex food matrix. Aptamer-target AFB1 specific recognition triggered linearly diminished 4-MBA signal intensity (I4-MBA) on the substrate to achieve a low detection limit of 58.9 pg/mL. Furthermore, the sensor has the potential to be a promising monitoring tool for other trace contaminants.

Fe-N-C single-atom nanozyme-linked immunosorbent assay for quantitative detection of aflatoxin B1

Aflatoxin B1 (AFB1) is a prominent food contaminant known for its high toxicity. Rapid, low-cost, and sensitive detection of AFB1 is an urgent demand for food safety risk control. In the traditional enzyme-linked immunosorbent assay (ELISA) method for AFB1 detection, horseradish peroxide (HRP) is high-cost and possesses poor environmental stability. In this study, a direct competitive single-atom nanozymes (SAzymes) -linked immunosorbent assay was developed based on Fe-N-C SAzymes. The proposed methods exhibited excellent sensitivity, rapid detection, fabrication, and low cost. Under the optimal conditions, the limit of detection of the new assay was 3.3 pg mL−1, with a quantitative relationship between 0.0084 and 0.358 ng mL−1. In addition, the developed method presented good recoveries in spiked samples, ranging from 84.50% and 103.75%, with coefficients of variation below 10%. Furthermore, the developed detection method showed good consistency (R2 = 0.9852) with the reference method, liquid chromatography/mass spectrometry (LC-MS/MS). To our knowledge, this is the first report about single-atom nanozymes-based ELISA for AFB1 determination. This work provides a feasible strategy for the rapid and sensitive detection of food contaminants using SAzymes.

A novel multimode biosensor for sensitive detection of AFB1 in food based on Mxenes nano enzymes.

In this work, Ti3C2 nano-enzymes (Ti3C2 NEs) materials with simulated peroxidase activity and fluorescence quenching properties were prepared. Then Ti3C2 NEs was functionalized using 6-carboxyfluorescein (FAM) labeled Aflatoxin B1 (AFB1) aptamers to construct a novel multimode nano enzyme biosensor for the detection of AFB1 in peanuts. Based on the fluorescence quenching characteristics and the superior simulated peroxidase activity of Ti3C2 NES and the specific binding of the aptamer to AFB1, the sensitive and rapid fluorescence/colorimetric/smart phone detection of AFB1 have been achieved, with detection limits of 0.09ngmL-1, 0.61ngmL-1 and 0.96ngmL-1, respectively. The analytical method provided can not only detect AFB1 in multiple modes, but also has a wider detection range, lower limit of detection (LOD) and better recovery rate, and can achieve on-site accurate detection of AFB1 content in peanuts, which has great application potential in the field of food quality testing.