An aptamer-based dipstick assay for the rapid and simple detection of aflatoxin B1

Biosensors and lateral flow immunoassays: Current state and future prospects

The advent of paper-based biosensors represents a novel paradigm in point-of-care (POC) diagnostics, emerging as versatile tools. However, the broad term "biosensors" can be misleading, encompassing a range of techniques such as dipstick assays, electrochemical, microfluidics and immunoassay-based biosensors (including lateral flow (LFA), vertical flow and nucleic acid-based immunoassays). This narrative review aims to consolidate the vast and dispersed information on biosensors into a systematically organized resource addressing both practical and theoretical aspects for researchers developing paper-based biosensors. It offers a comprehensive classification of biorecognition elements and labels, insights into various conjugation techniques, and characterization methods for both labels and conjugates. Following the development and optimization of biological reactions, this review emphasizes the careful selection of membranes and reagents to effectively reproduce molecular reactions on paper. Membranes are critical to biosensor efficacy, with fluid dynamics influenced by factors such as pore size, protein holding capacity and wicking rate. While POC diagnostics have traditionally provided binary (yes/no) results, advancements now allow for semi-quantitative and quantitative results. Technologies such as in-text, printers, various software's and smartphone can be used as colour analysis utilizing colour models beyond RGB like XYZ, grey intensity, CMY, CMYK, HSV and HSL that can analyse and process the colour intensity. AI integration further simplifies result analysis through image analysis, interpretation, predictive modelling, clinical decision support, enhancing detection, data integration and management. This review also emphasizes validation and stability studies in accordance with regulatory guidelines, ensuring the reliability of biosensors. The review ultimately covers: (i) A foundational understanding of various biosensor techniques, focusing on the self-sufficient LFA technique. (ii) Strategies to enhance sensitivity through pre- and post-assay modifications. (iii) A comprehensive troubleshooting section addressing common challenges in bioassay and fabrication. (iv) Multiplexing approaches enabling the simultaneous detection of multiple analytes for enhanced biomarker confirmation. By amalgamating knowledge from these approaches, this review offers the potential to elevate a basic traditional LFA strip into a highly sensitive diagnostic tool. It serves not only as a repository of knowledge but also as a roadmap for researchers and practitioners navigating the burgeoning field of paper-based biosensors.

Biosensors for Monitoring, Detecting, and Tracking Dissemination of Poultry-Borne Bacterial Pathogens Along the Poultry Value Chain: A Review

The poultry industry plays a crucial role in global food production, with chickens being the most widely consumed as a rich protein source. However, infectious diseases pose significant threats to poultry health, underscoring the need for rapid and accurate detection to enable timely intervention. In recent years, biosensors have emerged as essential tools to facilitate routine surveillance on poultry farms and rapid screening at slaughterhouses. These devices provide producers and veterinarians with timely information, thereby promoting proactive disease management. Biosensors have been miniaturized, and portable platforms allow for on-site testing, thereby enhancing biosecurity measures and bolstering disease surveillance networks throughout the poultry supply chain. Consequently, biosensors represent a transformative advancement in poultry disease management, offering rapid and precise detection capabilities that are vital for safeguarding poultry health and ensuring sustainable production systems. This section offers an overview of biosensors and their applications in detecting poultry diseases, with a particular emphasis on enteric pathogens.

Rapid detection of aflatoxin B1, zearalenone and ochratoxin A in grains by thermal desorption dielectric barrier discharge ionization mass spectrometry

Dielectric barrier discharge ionization is increasingly used for rapid detection in ambient mass spectrometry, although more often for gaseous and highly volatile samples than for solids and liquids. In this project, we present a rapid and sensitive method for detecting mycotoxins and demonstrate its capability for the detection of aflatoxin B1, zearalenone, and ochratoxin A in food samples. Our method is based on thermal desorption coupled to dielectric barrier discharge ionization mass spectrometry (TD-DBDI-MS), which we show generates minimal interferences and produces almost exclusively molecular ions. We detected mycotoxins in various food samples, including corn, peanuts, millet, and rice. Our method has a linear dynamic range of 1 μg kg-1 to 100 μg kg-1 for all three mycotoxins and a limit of detection (LOD) of 0.31 μg kg-1, 0.28 μg kg-1 and 0.43 μg kg-1, respectively. It is simple, rapid, reduces the pretreatment steps and has significant potential for practical applications.

A biosensor method based on surfactant-mediated surface droplet evaporation for the detection of Aflatoxin B1

Aflatoxin B1 (AFB1) is a common mycotoxin that is of significant global concern due to its impact on food safety. Herein, we innovatively develop a sensing platform to detect AFB1 based on evaporation of surfactant solutions on the hydrophobic surface, resulting in dried patterns with varied sizes. The surfactant CTAB solution produces a relatively large dried pattern due to the surface wetting. However, the reduction in the dried pattern size is found when the mixture of CTAB and AFB1 aptamer is tested, because the formation of CTAB/aptamer complex. Moreover, the dried pattern size of the mixture of CTAB, aptamer, and AFB1 increases due to the specific binding of AFB1 to its aptamer. Using this innovative strategy, the AFB1 detection can be fulfilled with a detection limit of 0.77 pg/mL. As a simple, convenient, inexpensive, and label-free method, the surfactant-mediated surface droplet evaporation-based biosensor is very promising for various potential applications.

Aflatoxin B1 exposure exacerbates chemokine receptor expression in the BTBR T+ Itpr3tf/J Mouse Model, unveiling insights into autism spectrum disorder: A focus on brain and spleen

OBJECTIVE

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by significant difficulties in social interaction, communication, and repeated stereotypic behaviour. Aflatoxin B1 (AFB1) is the most potent and well-known mycotoxin in various food sources. Despite its propensity to generate significant biochemical and structural changes in human and animal tissues, the influence of AFB1 on ASD has yet to be thoroughly studied. Mounting evidence indicates that chemokine receptors play a crucial function in the central nervous system and are implicated in developing several neuroinflammatory disorders. Chemokine receptors in individuals with ASD were elevated in the anterior cingulate gyrus astrocytes, cerebellum, and brain.

METHODS

The BTBR T+Itpr3tf/J (BTBR) mice are inbred strains that exhibit strong and consistently observed deficits in social interactions, characterized by excessive self-grooming and limited vocalization in social contexts. We examined the impact of AFB1 on CCR3-, CCR7-, CCR9-, CXCR3-, CXCR4-, and CXCR6-expressing I-A/I-E+ cells in the spleen of the BTBR mouse model of autism. We evaluated the mRNA levels of CCR3, CCR7, CCR9, CXCR3, CXCR4, and CXCR6 chemokine receptors in the brain.

RESULTS

The exposure to AFB1 in BTBR mice resulted in a significant rise in the number of I-A/I-E+CCR3+, I-A/I-E+CCR7+, I-A/I-E+CCR9+, I-A/I-E+CXCR3+, I-A/I-E+CXCR4+, and I-A/I-E+CXCR6+ cells. Furthermore, exposure to AFB1 increased mRNA expression levels of CCR3, CCR7, CCR9, CXCR3, CXCR4, and CXCR6 in the brain.

CONCLUSIONS

These findings highlight that AFB1 exposure increases the expression of chemokine receptors in BTBR mice, indicating the necessity for further research into AFB1's role in the development of ASD.

In vitro selection of DNA aptamers against staphylococcal enterotoxin A

Staphylococcal enterotoxin A (SEA) is the most frequently reported in staphylococcal food poisoning (SFP) outbreaks. Aptamers are single-stranded nucleic acids that are seen as promising alternatives to antibodies in several areas, including diagnostics. In this work, systematic evolution of ligands by exponential enrichment (SELEX) was used to select DNA aptamers against SEA. The SELEX protocol employed magnetic beads as an immobilization matrix for the target molecule and real-time quantitative PCR (qPCR) for monitoring and optimizing sequence enrichment. After 10 selection cycles, the ssDNA pool with the highest affinity was sequenced by next generation sequencing (NGS). Approximately 3 million aptamer candidates were identified, and the most representative cluster sequences were selected for further characterization. The aptamer with the highest affinity showed an experimental dissociation constant (KD) of 13.36 ± 18.62 nM. Increased temperature negatively affected the affinity of the aptamer for the target. Application of the selected aptamers in a lateral flow assay demonstrated their functionality in detecting samples containing 100 ng SEA, the minimum amount capable of causing food poisoning. Overall, the applicability of DNA aptamers in SEA recognition was demonstrated and characterized under different conditions, paving the way for the development of diagnostic tools.

Recent advances in nucleic acid signal amplification-based aptasensors for sensing mycotoxins

Mycotoxin contamination in food products may cause serious health hazards and economic losses. The effective control and accurate detection of mycotoxins have become a global concern. Even though a variety of methods have been developed for mycotoxin detection, most conventional methods suffer from complicated operation procedures, low sensitivity, high cost, and long assay time. Therefore, the development of simple and sensitive methods for mycotoxin assay is highly needed. The introduction of nucleic acid signal amplification technology (NASAT) into aptasensors significantly improves the sensitivity and facilitates the detection of mycotoxins. Herein, we give a comprehensive review of the recent advances in NASAT-based aptasensors for assaying mycotoxins and summarize the principles, features, and applications of NASAT-based aptasensors. Moreover, we highlight the challenges and prospects in the field, including the simultaneous detection of multiple mycotoxins and the development of portable devices for field detection.

A comprehensive review of mycotoxins: Toxicology, detection, and effective mitigation approaches

Mycotoxins, harmful compounds produced by fungal pathogens, pose a severe threat to food safety and consumer health. Some commonly produced mycotoxins such as aflatoxins, ochratoxin A, fumonisins, trichothecenes, zearalenone, and patulin have serious health implications in humans and animals. Mycotoxin contamination is particularly concerning in regions heavily reliant on staple foods like grains, cereals, and nuts. Preventing mycotoxin contamination is crucial for a sustainable food supply. Chromatographic methods like thin layer chromatography (TLC), gas chromatography (GC), high-performance liquid chromatography (HPLC), and liquid chromatography coupled with a mass spectrometer (LC/MS), are commonly used to detect mycotoxins; however, there is a need for on-site, rapid, and cost-effective detection methods. Currently, enzyme-linked immunosorbent assays (ELISA), lateral flow assays (LFAs), and biosensors are becoming popular analytical tools for rapid detection. Meanwhile, preventing mycotoxin contamination is crucial for food safety and a sustainable food supply. Physical, chemical, and biological approaches have been used to inhibit fungal growth and mycotoxin production. However, new strains resistant to conventional methods have led to the exploration of novel strategies like cold atmospheric plasma (CAP) technology, polyphenols and flavonoids, magnetic materials and nanoparticles, and natural essential oils (NEOs). This paper reviews recent scientific research on mycotoxin toxicity, explores advancements in detecting mycotoxins in various foods, and evaluates the effectiveness of innovative mitigation strategies for controlling and detoxifying mycotoxins.

A simple photoelectrochemical aptasensor based on MoS2/rGO for aflatoxin B1 detection in grain crops

Designing a simple and sensitive photoelectrochemical (PEC) sensor is crucial to addressing the limitations of routine analytical methods. The sensitivity of the PEC sensor, however, relies on the photoelectric material used. In this manuscript, composites of MoS2/rGO (MG) with a large area and layered structure are prepared by simple steps. This material exhibits sensitivity to visible light and demonstrates outstanding photoelectric conversion performance. The constructed PEC aptasensor using this material to detect aflatoxin B1 (AFB1) shows significantly higher sensitivity and stability compared to similar sensors. This may be attributed to the presence of surface defects in MoS2, which provide more active sites for photocatalysis. Additionally, graphene oxide (GO) is reduced to rGO by thiourea and forms a heterojunction with MoS2, enhancing charge carrier separation and interfacial electron transfer. Our research has revealed that the photocurrent intensity of the aptamer electrode decreases with an increase in AFB1 concentration, resulting in a "signal-off" PEC aptasensor. The detection limit of this aptasensor is 2.18 pg mL-1, with a linear range of 0.001 to 100 ng mL-1. This result will also provide a reference for the study of other mycotoxins in food.

Recent Progress of Electrochemical Aptasensors toward AFB1 Detection (2018-2023)

Food contaminants represent possible threats to humans and animals as severe food safety hazards. Prolonged exposure to contaminated food often leads to chronic diseases such as cancer, kidney or liver failure, immunosuppression, or genotoxicity. Aflatoxins are naturally produced by strains of the fungi species Aspergillus, which is one of the most critical and poisonous food contaminants worldwide. Given the high percentage of contaminated food products, traditional detection methods often prove inadequate. Thus, it becomes imperative to develop fast, accurate, and easy-to-use analytical methods to enable safe food products and good practices policies. Focusing on the recent progress (2018-2023) of electrochemical aptasensors for aflatoxin B1 (AFB1) detection in food and beverage samples, without pretending to be exhaustive, we present an overview of the most important label-free and labeled sensing strategies. Simultaneous and competitive aptamer-based strategies are also discussed. The aptasensors are summarized in tabular format according to the detection mode. Sample treatments performed prior analysis are discussed. Emphasis was placed on the nanomaterials used in the aptasensors' design for aptamer-tailored immobilization and/or signal amplification. The advantages and limitations of AFB1 electrochemical aptasensors for field detection are presented.

Poly-adenine-mediated tetrahedral DNA nanostructure with multiple target-recognition sites for ultrasensitive and rapid electrochemical detection of Aflatoxin B1

Tetrahedral DNA nanostructures (TDNs) are widely used in the development of electrochemical biosensors due to their structural stability, programmability, and strong interfacial orderliness. However, the complex modifications on the electrode and the single vertex target recognition of the TDNs limit their applications in electrochemical biosensing. Herein, we developed a universal detection system based on a novel polyadenine-based tetrahedral DNA nanostructure (ATDN) using Aflatoxin B1 (AFB1) as the model target for analysis. In the absence of target AFB1, the signal probes (SP) modified with ferrocene would be anchored by five aptamers on ATDN. The target capture by aptamers led to a release of SP from the electrode surface, resulting in a significant reduction of the electrochemical signal. This new nanostructure was not only dispensed with multi-step electrode modifications and strong mechanical rigidity but also had five modification sites which enhanced the detection sensitivity for the target. As a result, this biosensor shows good analytical performance in the linear range of 1 fg mL-1 to 1 ng mL-1, exhibiting a low detection limit of 0.33 fg mL-1. Satisfactory accuracy has also been demonstrated through good recoveries (95.2%-98.9%). The proposed new tetrahedral DNA nanostructure can provide a more rapid and sensitive alternative to previous electrochemical sensors based on the conventional TDN. Since DNA sequences can be designed flexibly, the sensing platform in this strategy can be extended to detect various targets in different fields.

Supramolecular Nucleic Acid-Based Organosilica Nanoparticles Responsive to Physical and Biological Inputs

Organosilica nanoparticles that contain responsive organic building blocks as constitutive components of the silica network offer promising opportunities for the development of innovative drug formulations, biomolecule delivery, and diagnostic tools. However, the synthetic challenges required to introduce dynamic and multifunctional building blocks have hindered the realization of biomimicking nanoparticles. In this study, capitalizing on our previous research on responsive nucleic acid-based organosilica nanoparticles, we combine the supramolecular programmability of nucleic acid (NA) interactions with sol-gel chemistry. This approach allows us to create dynamic supramolecular bridging units of nucleic acids in a silica-based scaffold. Two peptide nucleic acid-based monoalkoxysilane derivatives, which self-assemble into a supramolecular bis-alkoxysilane through direct base pairing, were chosen as the noncovalent units inserted into the silica network. In addition, a bridging functional NA aptamer leads to the specific recognition of ATP molecules. In a one-step bottom-up approach, the resulting supramolecular building blocks can be used to prepare responsive organosilica nanoparticles. The supramolecular Watson-Crick-Franklin interactions of the organosilica nanoparticles result in a programmable response to external physical (i.e., temperature) and biological (i.e., DNA and ATP) inputs and thus pave the way for the rational design of multifunctional silica materials with application from drug delivery to theranostics.

New technologies and reagents in lateral flow assay (LFA) designs for enhancing accuracy and sensitivity

Lateral flow assays (LFAs) are a popular method for quick and affordable diagnostic testing because they are easy to use, portable, and user-friendly. However, LFA design has always faced challenges regarding sensitivity, accuracy, and complexity of the operation. By integrating new technologies and reagents, the sensitivity and accuracy of LFAs can be improved while minimizing the complexity and potential for false positives. Surface enhanced Raman spectroscopy (SERS), photoacoustic techniques, fluorescence resonance energy transfer (FRET), and the integration of smartphones and thermal readers can improve LFA accuracy and sensitivity. To ensure reliable and accurate results, careful assay design and validation, appropriate controls, and optimization of assay conditions are necessary. Continued innovation in LFA technology is crucial to improving the reliability and accuracy of rapid diagnostic testing and expanding its applications to various areas, such as food testing, water quality monitoring, and environmental testing.

Construction of a nanoscale metal-organic framework aptasensor for fluorescence ratiometric sensing of AFB1 in real samples

Aflatoxins B1 (AFB1) that could contaminate agricultural products has received sustained attention due to its high toxicity and wide distribution. Therefore, sensitive and facile detection method for AFB1 is significant for food safety and control. In this work, a ratiometric fluorescence NMOFs-Aptasensor was developed based on the combination of Cy3-modified aptamer and zirconium-based nanoscale metal-organic frameworks (NMOFs). NMOFs served as energy donors, and Cy3 labeled on the AFB1 aptamer was used as an acceptor. An energy donor-acceptor pair was fabricated in the NMOFs-Aptasensor. With AFB1 selectively caught by the AFB1 aptamer, the fluorescence of the NMOFs-Aptasensor changed via fluorescence resonance energy transfer (FRET), and the fluorescence spectra changed accordingly. The ratiometric fluorescence signal was utilized to quantitatively measure AFB1. The reported NMOFs-Aptasensor presented great detection performance from 0 to 3.33 ng mL^-1, with an LOD of 0.08 ng mL^-1. Moreover, the fluorescence sensor was successfully applied to detect AFB1 in real samples.

Use of Lateral Flow Assays in Forensics

Already for some decades lateral flow assays (LFAs) are 'common use' devices in our daily life. Also, for forensic use LFAs are developed, such as for the analysis of illicit drugs and DNA, but also for the detection of explosives and body fluid identification. Despite their advantages, including ease-of-use, LFAs are not yet frequently applied at a crime scene. This review describes (academic) developments of LFAs for forensic applications, focusing on biological and chemical applications, whereby the main advantages and disadvantages of LFAs for the different forensic applications are summarized. Additionally, a critical review is provided, discussing why LFAs are not frequently applied within the forensic field and highlighting the steps that are needed to bring LFAs to the forensic market.

The application of nanoparticles in point-of-care testing (POCT) immunoassays

The Covid-19 pandemic has led to greater recognition of the importance of the fast and timely detection of pathogens. Recent advances in point-of-care testing (POCT) technology have shown promising results for rapid diagnosis. Immunoassays are among the most extensive POCT assays, in which specific labels are used to indicate and amplify the immune signal. Nanoparticles (NPs) are above the rest because of their versatile properties. Much work has been devoted to NPs to find more efficient immunoassays. Herein, we comprehensively describe NP-based immunoassays with a focus on particle species and their specific applications. This review describes immunoassays along with key concepts surrounding their preparation and bioconjugation to show their defining role in immunosensors. The specific mechanisms, microfluidic immunoassays, electrochemical immunoassays (ELCAs), immunochromatographic assays (ICAs), enzyme-linked immunosorbent assays (ELISA), and microarrays are covered herein. For each mechanism, a working explanation of the appropriate background theory and formalism is articulated before examining the biosensing and related point-of-care (POC) utility. Given their maturity, some specific applications using different nanomaterials are discussed in more detail. Finally, we outline future challenges and perspectives to give a brief guideline for the development of appropriate platforms.

Impedimetric Polyaniline-Based Aptasensor for Aflatoxin B1 Determination in Agricultural Products

An impedimetric aptasensor based on a polyaniline (PAni) support matrix is developed through the surface modification of a screen-printed carbon electrode (SPE) for aflatoxin B₁ (AFB₁) detection in foodstuffs and feedstuffs for food safety. The PAni is synthesized with the chemical oxidation method and characterized with potentiostat/galvanostat, FTIR, and UV-vis spectroscopy techniques. The stepwise fabrication procedure of the PAni-based aptasensor is characterized by means of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. The impedimetric aptasensor is optimized using the EIS technique, and its feasibility of detecting AFB₁ in real sample matrices is evaluated via a recovery study in spiked foodstuffs and feedstuffs, such as pistachio nuts, cinnamons, cloves, corn, and soybeans, with a good recovery percentage, ranging from 87.9% to 94.7%. The charge transfer resistance (R_CT) at the aptasensor interface increases linearly with the AFB₁ concentration in the range of 3 × 10^-2 nM to 8 × 10^-2 nM, with a regression coefficient (R²) value of 0.9991 and detection limit of 0.01 nM. The proposed aptasensor is highly selective towards AFB₁ and partially selective to AFB₂ and ochratoxin A (OTA) due to their similar structures that differ only at the carbon-carbon double bond located at C₈ and C₉ and the large molecule size of OTA.

CRISPR/Cas12a-Assisted Chemiluminescence Sensor for Aflatoxin B1 Detection in Cereal Based on Functional Nucleic Acid and In-Pipet Rolling Circle Amplification

Herein, we report a CRISPR/Cas12a-assisted chemiluminescence sensor for aflatoxin B₁ (AFB₁) detection based on functional nucleic-acid-mediated target recognition and in-pipet rolling circle amplification-mediated signal amplification. In this sensor, we performed rolling circle amplification on the inside of the pipet to enrich horseradish peroxidase (pipet-poly-HRP). When AFB₁ is present, it interacts with functional nucleic acids and results in the release of the activator. The activator is designed to activate the CRISPR/Cas12a system, which cleaves the pipet-poly-HRP to liberate HRP. The freed HRP can then be measured by chemiluminescence to quantify AFB₁. This CRISPR/Cas12a-assisted chemiluminescence sensor enables facile, highly sensitive, and specific detection of AFB₁, with a linear range from 50 pg/mL to 100 ng/mL and a detection limit of 5.2 pg/mL. Furthermore, it exhibits satisfactory recovery and has successfully challenged AFB₁ detection in cereal samples. The proposed sensor offers a novel rapid screening approach that holds great promise for food security monitoring.

Impedimetric nanoimmunosensor platform for aflatoxin B1 detection in peanuts

This article developed a novel electrochemical immunosensor for the specific detection of aflatoxin B1 (AFB1). Amino-functionalized iron oxide nanoparticles (Fe₃ O₄ -NH₂ ) were synthesized. Fe₃ O₄ -NH₂ were chemically bound on self-assembly monolayers (SAMs) of mercaptobenzoic acid (MBA). Finally, polyclonal antibodies (pAb) were immobilized on Fe₃ O₄ -NH₂ -MBA. The sensor system was evaluated through atomic force microscopy (AFM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). A reduction in the anodic and cathodic peak currents was observed after the assembly of the sensor platform. The charge transfer resistance (R_ct ) was increased due to the electrically insulating bioconjugates. Then, the specific interaction between the sensor platform and AFB1 blocks the electron transfer of the [Fe(CN)₆ ]^3-/4- redox pair. The nanoimmunosensor showed a linear response range estimated from 0.5 to 30 μg/mL with a limit of detection (LOD) of 9.47 μg/mL and a limit of quantification (LOQ) of 28.72 μg/mL for AFB1 identification in a purified sample. In addition, a LOD of 3.79 μg/mL, a LOQ of 11.48 μg/mL, and a regression coefficient of 0.9891 were estimated for biodetection tests on peanut samples. The proposed immunosensor represents a simple alternative, successfully applied in detecting AFB1 in peanuts, and therefore, represents a valuable tool for ensuring food safety.

Aptasensor-based assay for dual-readout determination of aflatoxin B1 in corn and wheat via an electrostatic force-mediated FRET strategy

A rapid and sensitive aptasensor was established for the dual-readout determination of aflatoxin B1 (AFB1) utilizing an electrostatically mediated fluorescence resonance energy transfer (FRET) signal amplification strategy. In the presence of AFB1, the aptamer preferentially bound to AFB1, resulting in the aggregation of bare gold nanoparticles (AuNPs) induced by NaCl, accompanied by a change of AuNP solution from wine-red to purple. This color change was used for colorimetric channel analysis. Then, the positively charged quantum dots were introduced into reaction system and interacted with negatively charged AuNPs, which successfully converted the color signal into a more sensitive fluorescence signal through FRET. The fluorescence quenching efficiency decreased with increasing concentrations of AFB1, and the fluorescence of aptasensor gradually recovered. The variation of fluorescence intensity was employed for fluorometric channel analysis. Under the optimal conditions, the color and fluorescence signals exhibited excellent response to AFB1 concentration within the ranges 10-320 ng·mL^-1 and 3-320 ng·mL^-1, respectively, and the limit of detection was as low as 7.32 ng·mL^-1 and 1.48 ng·mL^-1, respectively. The proposed aptasensor exhibited favorable selectivity, good recovery (85.3-113.4% in spiked corn and wheat samples), stable reproducibility (RSD<13.3%), and satisfactory correlation with commercial kits (R²=0.998). The aptasensor developed integrates advantages of modification-free, dual-readout, self-calibration, easy operation, and cost-effectiveness, while providing a simple and universal strategy for rapid and sensitive detection of mycotoxins in foodstuffs.

A Novel and Label-Free Chemiluminescence Detection of Zearalenone Based on a Truncated Aptamer Conjugated with a G-Quadruplex DNAzyme

Zearalenone (ZEN), one of the most frequently occurring mycotoxin contaminants in foods and feeds, poses considerable threat to human and animal health, owing to its acute and chronic toxicities. Thus, rapid and accurate detection of ZEN has attracted broad research interest. In this work, a novel and label-free chemiluminescence aptasensor based on a ZEN aptamer and a G-quadruplex DNAzyme was constructed. It was established on a competitive assay between ZEN and an auxiliary DNA for the aptamer, leading to activation of the G-quadruplex/hemin DNAzyme and subsequent signal amplification by chemiluminescence generation after substrate addition. To maximize the detection sensitivity, numerous key parameters including truncated aptamers were optimized with molecular docking analysis. Upon optimization, our aptasensor exhibited a perfect linear relationship (R² = 0.9996) for ZEN detection in a concentration range of 1-100 ng/mL (3.14-314.10 nM) within 40 min, achieving a detection limit of 2.85 ng/mL (8.95 nM), which was a 6.7-fold improvement over that before optimization. Most importantly, the aptasensor obtained a satisfactory recovery rate of 92.84-137.27% and 84.90-124.24% for ZEN-spiked wheat and maize samples, respectively. Overall, our label-free chemiluminescence aptasensor displayed simplicity, sensitivity, specificity and practicality in real samples, indicating high application prospects in the food supply chain for rapid detection of ZEN.

Aptamer-based NanoBioSensors for seafood safety

Chemical and biological contaminants are of primary concern in ensuring seafood safety. Rapid detection of such contaminants is needed to keep us safe from being affected. For over three decades, immunoassay (IA) technology has been used for the detection of contaminants in seafood products. However, limitations inherent to antibody generation against small molecular targets that cannot elicit an immune response, along with the instability of antibodies under ambient conditions greatly limit their wider application for developing robust detection and monitoring tools, particularly for non-biomedical applications. As an alternative, aptamer-based biosensors (aptasensors) have emerged as a powerful yet robust analytical tool for the detection of a wide range of analytes. Due to the high specificity of aptamers in recognising targets ranging from small molecules to large proteins and even whole cells, these have been suggested to be viable molecular recognition elements (MREs) in the development of new diagnostic and biosensing tools for detecting a wide range of contaminants including heavy metals, antibiotics, pesticides, pathogens and biotoxins. In this review, we discuss the recent progress made in the field of aptasensors for detection of contaminants in seafood products with a view of effectively managing their potential human health hazards. A critical outlook is also provided to facilitate translation of aptasensors from academic laboratories to the mainstream seafood industry and consumer applications.

A highly sensitive competitive aptasensor for AFB1 detection based on an exonuclease-assisted target recycling amplification strategy

Aflatoxin B₁ (AFB₁) is a typical mycotoxin found in agricultural products, and poses a huge threat to both humans and animals. Accurate and rapid measurement of AFB₁ is essential for environmental analysis and food safety. Based on molecular docking simulation design and exonuclease-assisted target recycling amplification, we designed a competitive fluorescence aptasensor to detect AFB₁ rapidly and sensitively. According to the molecular docking simulations, a complementary strand (cDNA) was designed by searching for potential binding sites of the aptamer, which had the lowest binding energy. Magnetic beads modified with biotin-Apt were used as the capture probe, while FAM-labeled cDNA acted as the reporter probe. By using EXO I for target recycling amplification, this aptasensor was highly sensitive and selective for AFB₁. The detection limit of the suggested aptasensor under optimal conditions was 0.36 ng mL^-1 (S/N = 3) in the range of 1-1000 ng mL^-1 (R² = 0.991). The developed aptasensor was successfully used to analyze AFB₁ in oil samples.

Chromatographic methods for rapid aflatoxin B1 analysis in food: a review

Aflatoxin B1 (AFB1) is a mycotoxin and is the most carcinogenic of all known chemicals. In view of the AFB1 characteristics of widespread distribution, serious pollution, great harm to humans, and animals and difficult to remove, it is urgent to develop a convenient and sensitive detection method. Moreover, chromatographic test strips (CTSs) are a rapid detection technology that combines labeling technology with chromatography technology. CTSs have been widely used in the fields of environmental monitoring, medical diagnosis, and food safety analysis in recent years. Different from other immune assays, they have the advantages of short measuring time, low cost, high efficiency and no need for professionals to operate. In addition, the introduction of nanomaterials has laid a good foundation for the detection of high sensitivity, high specificity and high efficiency via CTSs. Herein, we tend to comprehensively introduce the applications of chromatographic methods in AFB1 detection and pay attention to the signal detection modes based on nanomaterials in antibody-based immunochromatographic strips (ICSs), such as colorimetric, fluorescent, chemiluminescent, and Raman scattering sensing. Some typical examples are also listed in this review. In the end, we make a summary and put forward prospects for the development of CTSs.

Aflatoxin tests in herbal products and its quantification: Latest updates

Aflatoxin is naturally occurring mycotoxins produced by fungi. The existence of aflatoxin in herbal medicines is a well-known issue. The detection of aflatoxin with good sensitivity and also that is reliable in complex matrices like herbs usually necessitates difficult processes and powerful detection instrument in preparation of sample. This study investigated the global occurrence of aflatoxin contamination herbal products. This article pivots on key breakthroughs in preparation of sample and its importance in analytical technology. Studies from published studies were screened to determine the general level of aflatoxin contamination. The countries involved were Malaysia, Indonesia, Kenya, Brazil, Nigeria, Thailand, South Africa, and Morocco. This review also includes recent studies on the development and application of screening assays such as lateral flow immunoassays, enzyme-linked immunosorbent assays, aptamer-based lateral flow assays, and cytometric bead arrays, as well as traditional chromatographic techniques for aflatoxin qualification or quantitation. The current study looks at aflatoxin contamination of key herbal drug raw material, which are frequently used in the production of numerous herbal pharmaceuticals. Contamination of aflatoxin might occur in herbal products if the ingredients such as medicinal herbs and plants that are used in manufacturing of herbal products are not dried thoroughly or stored inappropriately after preparation.

Advanced Carbon-Based Polymeric Nanocomposites for Forensic Analysis

Nanotechnology is a powerful tool and fast-growing research area in many novel arenas, ranging from biomedicine to engineering and energy storage. Nanotechnology has great potential to make a significant positive contribution in forensic science, which deals with the identification and investigation of crimes, finding relationships between pieces of evidence and perpetrators. Nano-forensics is related to the development of nanosensors for crime investigations and inspection of terrorist activity by analyzing the presence of illicit drugs, explosives, toxic gases, biological agents, and so forth. In this regard, carbon nanomaterials have huge potential for next-generation nanosensors due to their outstanding properties, including strength combined with flexibility, large specific surface area, high electrical conductivity, and little noise. Moreover, their combination with polymers can provide nanocomposites with novel and enhanced performance owed to synergy between the composite components. This review concisely recapitulates up-to-date advances in the development of polymer composites incorporating carbon-based nanomaterials for forensic science. The properties of the different carbon nanomaterials, several methods used to analyze functional polymeric nanocomposites, and their applications in forensic investigation are discussed. Furthermore, present challenges and forthcoming outlooks on the design of new polymer/carbon nanomaterial composites for crime prevention are highlighted.

Development of a Lateral Flow Strip with a Positive Readout for the On-Site Detection of Aflatoxin B1

Aflatoxin B₁ is one of the contamination indicators for food safety monitoring. The rapid and effective assessment and determination of AFB₁ in food is of great importance to dietary safety. The lateral flow assay shows advantages in its simplicity, and rapidity, and provides a visual readout, while the available lateral flow assay for AFB₁ requires a competitive format that produces readings inversely proportional to the AFB₁ concentration, which is counterintuitive and may lead to a potential misinterpretation of the results. Herein, we developed a positive readout aptamer-based lateral flow strip (Apt-strip) for the detection of AFB₁. This Apt-strip relies on the competition between AFB₁ and fluorescein-labeled complementary DNA strands (FAM-cDNA) for affinity binding to limited aptamers against AFB₁ (AFB₁-Apt). In the absence of AFB₁, AFB₁-Apt hybridizes with FAM-cDNA. No signal at the T-line of the Apt-strip was observed. In contrast, AFB₁-Apt binds to AFB₁ in the sample, and then a part of the FAM-cDNA is hybridized with the free AFB₁-Apt, at which time the other unreacted FAM-cDNA is captured by A35-Apt on the T-line. The signal was observed. This method achieved fast detection of AFB₁ with a detection limit (DL) of 0.1 ng/mL, positive readout, and increased sensitivity.

Visual detection of aflatoxin B1 based on specific aptamer recognition combining with triple amplification strategy

A highly sensitive and specific visual detection method for aflatoxin B1 (AFB1) based on the target specificity of aptamer, rolling circle amplification (RCA) and enzyme catalysis biological amplification effect has been established. In this work, AFB1 aptamer immobilized on the surface of magnetic beads (MB) serves as a molecular recognition probe. In the absence of AFB1, the aptamer and auxiliary linking probe (LP) maintain a double stranded state due to partial base pair complementarities. By contrast, in the presence of AFB1, the aptamer preferentially binds to AFB1 specifically, and the LP later restores to a single stranded state. Subsequently, the RCA reaction is triggered by above-mentioned single stranded LP to generate long DNA strands, which are employed to capture amounts of signal probes (SP) and horse radish peroxidases (HRP). Finally, amounts of HRP catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by H₂O₂ and leads to a dramatic color change of the solution from colorlessness to deep blue as a signal indicator, obtaining a high sensitivity, high specificity and visual detection of AFB1. Under optimal conditions, a good linear detection range (0.5-40 pg·mL^-1) was achieved, and the limit of detection (LOD) was 0.13 pg·mL^-1. Besides, the proposed aptasensor showed excellent specificity for AFB1 compared with five other mycotoxins. More than that, all reactions occur on the surface of the magnetic beads, which not only facilitates the detection operation process including the efficient isolation and collection of AFB1 from sample matrix, but also gets better selectivity and stronger resistibility to target analyte in complex sample matrix, adequately indicating its potential application in AFB1 practical detection.

Synthesis of recyclable GO/Cu3(BTC)2/Fe3O4 hybrid nanocomposites with enhanced photocatalytic degradation of aflatoxin B1

This study evaluated the photocatalytic performance of the activated carbon assisted GO/Cu₃(BTC)₂/Fe₃O₄ photocatalyst for aflatoxin B1 (AFB1) degradation under ultraviolet light. The nanocomposite was characterized by Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption-desorption. The numerous factors influencing the degradation efficiency of AFB1 including catalyst dose, pH importance, and contact time were also probed. The elevated degradation performance of AFB1 by 99% was due to a larger surface area and improved GO/Cu₃(BTC)₂/Fe₃O₄ photocatalyst. The degradation process followed a pseudo-first-order kinetic model. Moreover, it is possible to quickly isolate the catalyst from the solution and retain successful operation. In the degradation of AFB1, the hole(h⁺) and the hydroxyl radicals(OH) were found to play a significant role. These studies showed that GO/Cu₃(BTC)₂/Fe₃O₄ has high capturing capacity and photoactivity synergy, thereby offering a quick effect, and green solution to AFB1 degradation.

A Sensitive Aptasensor Using Biotin-Streptavidin System for Patulin Detection in Apple Juice

Patulin contamination in fruits, vegetables, and their products is considered a serious health risk factor for food safety and human health. Thus, a rapid, simple detection method for patulin is becoming important, which could provide a tool for routine screening and food surveys. The objective of this study was to develop a sensitive aptamer-based lateral flow assay (FLA) using Streptavidin functionalized gold nanoparticles for sensitive patulin detection. An excellent dynamic range for patulin detection was obtained (2.7~139.8 ng/mL in the buffer and 7.07~359.5 ng/mL in the sample) with no affinity for other mycotoxins such as zearalenone (ZEN), ochratoxin A (OTA), aflatoxin B1 (AFB1), citrinin or tenuazonic acid (TEA). The limit of detection was 0.19 ng/mL in the buffer and 0.36 ng/mL in the real sample. The recoveries were 83.3% to 107.1%, with a satisfactory RSD value from 6.5% to 7.5%. Hence the established LFA could be used as a rapid, simple, on-site screening tool for PAT determination in apple juice.

Recent Progress in Rapid Determination of Mycotoxins Based on Emerging Biorecognition Molecules: A Review

Mycotoxins are secondary metabolites produced by fungal species, which pose significant risk to humans and livestock. The mycotoxins which are produced from Aspergillus, Penicillium, and Fusarium are considered most important and therefore regulated in food- and feedstuffs. Analyses are predominantly performed by official laboratory methods in centralized labs by expert technicians. There is an urgent demand for new low-cost, easy-to-use, and portable analytical devices for rapid on-site determination. Most significant advances were realized in the field bioanalytical techniques based on molecular recognition. This review aims to discuss recent progress in the generation of native biomolecules and new bioinspired materials towards mycotoxins for the development of reliable bioreceptor-based analytical methods. After brief presentation of basic knowledge regarding characteristics of most important mycotoxins, the generation, benefits, and limitations of present and emerging biorecognition molecules, such as polyclonal (pAb), monoclonal (mAb), recombinant antibodies (rAb), aptamers, short peptides, and molecularly imprinted polymers (MIPs), are discussed. Hereinafter, the use of binders in different areas of application, including sample preparation, microplate- and tube-based assays, lateral flow devices, and biosensors, is highlighted. Special focus, on a global scale, is placed on commercial availability of single receptor molecules, test-kits, and biosensor platforms using multiplexed bead-based suspension assays and planar biochip arrays. Future outlook is given with special emphasis on new challenges, such as increasing use of rAb based on synthetic and naïve antibody libraries to renounce animal immunization, multiple-analyte test-kits and high-throughput multiplexing, and determination of masked mycotoxins, including stereoisomeric degradation products.

Recent progress in fluorescent aptasensors for the detection of aflatoxin B1 in food

Aflatoxin B1 pollution is one of the most critical issues of food safety and has been categorized as a group I carcinogen by the International Agency for Research on Cancer. Aflatoxin B1 exists in various foods and feedstuff products and can be produced and contaminate food products in all processes, including growth, harvest, storage, or processing. Therefore, it is of great value for detecting and on-site monitoring aflatoxin B1. Aptamers are short single-stranded DNA or RNA obtained from the nucleic acid molecular library through SELEX. With advantages of high specificity, large affinity, and easy modification, aptasensors have become popular in a wide range of promising applications. This review focuses on recent advances on fluorescent aptamer sensors for the detection of aflatoxin B1, including their design strategies, working mechanisms, and applications to on-site detection. Finally, the current challenges and prospects are discussed.

Highly sensitive and selective lateral flow aptasensor for anti-coagulant dabigatran etexilate determination in blood

Dabigatran etexilate (DBG) is a new anticoagulant drug (commercially sold under the names Pradaxa® and Pradax™) that replaces Warfarin, the landmark agent for anticoagulation therapy. Inadequate administration of DBG or in the cases of massive bleeding that occurs after renal impairment, DBG therapy can carry a substantial life-threatening risks. One of the major limitations of DBG treatment is the lack of a simple and quick tool for measuring its level in blood in the case of massive bleedings or emergency operations. In this work, we have incorporated a previously isolated aptamer for DBG to develop a simple competitive lateral flow aptasensor (LFA) for the determination of DBG in buffer and blood samples. A full-length 60-mer aptamer as well as a truncated 38-mer aptamer were conjugated to gold nanoparticles (AuNPs) via thiol-Au coupling chemistry. After appropriate AuNP surface passivation steps, the aptamer's core region was hybridized with 8-mer biotinylated sequences. The conjugated particles could be capture on the test line by the interaction of the biotin molecules with a previously deposited streptavidin. Incubation of the conjugated particles with DBG causes the aptamer to undergo a conformational change that releases the 8-mer biotinylated sequences and result in the disappearance of the test line. Lysozyme protein was used to construct the control line that non-specifically interacts with the conjugated particles whether or not the target compound is present. The developed LFA achieves 20 nM detection level in buffer and blood samples, operates within the nanomolar range, and shows excellent selectivity against potential interfering molecules. The developed sensor could help assessing the levels of DBG in medical conditions that require rapid interventions.

Aptamer-based lateral flow assay on-site biosensors

The lateral flow assay (LFA) is a widely used paper-based on-site biosensor that can detect target analytes and obtain test results in several minutes. Generally, antibodies are utilized as the biorecognition molecules in the LFA. However, antibodies selected using an in vivo process not only may risk killing the animal hosts and causing errors between different batches but also their range is restricted by the refrigerated conditions used to store them. To avoid these limitations, aptamers screened by an in vitro process have been studied as biorecognition molecules in LFAs. Based on the sandwich or competitive format, the aptamer-based LFA can accomplish on-site detection of target analytes. Since aptamers have a distinctive ability to undergo conformational changes, the adsorption-desorption format has also been exploited to detect target analytes in aptamer-based LFAs. This paper reviews developments in aptamer-based LFAs in the last three years for the detection of target analytes. Three formats of aptamer-based LFAs, i.e., sandwich, competitive, and adsorption-desorption, are described in detail. Based on these formats, signal amplification strategies and multiplexed detection are discussed in order to provide an overview of aptamer-based LFAs for on-site detection of target analytes. In addition, the potential commercialization and future perspectives of aptamer-based LFAs for rapid detection of SARS-CoV-2 are given to support the COVID-19 pandemic.

Determination of minimal sequence for zearalenone aptamer by computational docking and application on an indirect competitive electrochemical aptasensor

Aptamers are short single-stranded oligonucleotides (either DNA or RNA) that can fold into well-defined three-dimensional (3D) spatial structures which enable them to capture their specific target by complementary shape interactions. Aptamers are selected from large random libraries through the SELEX process and only a small fraction of the sequence is involved in direct docking with the target. In this paper, we describe the possible truncation variants of zearalenone (ZEA) aptamer which might be an effective binding region for the target. The originally selected zearalenone (ZEA) aptamer was 80-mer in length and shown to bind the target with a high affinity (K_d = 41 ± 5 nM). Herein, computational docking simulation was performed with 15 truncated variants to determine the predicted binding energy and responsible binding site of the aptamer-analyte complex. The results revealed that 5 truncated variants had binding energy lower than - 7.0 kcal/mol. Circular dichroism analysis was performed on the shortlisted aptamer and the conformational change of aptamers was observed with the presence of an analyte. Aptamer Z3IN (29-mer) was chosen as the most enhanced affinity for its target with a dissociation constant of 11.77 ± 1.44 nM. The aptamer was further applied in the electrochemical aptasensor of ZEA based on an indirect competitive format. The results demonstrated that the truncated aptamer leads to an enhancement of the sensitivity of the biosensor.

Recent progress in visual methods for aflatoxin detection

Aflatoxins (AFs) contamination in food and agricultural products poses a significant threat to human health. Sensitive and accurate detection of AFs provides a strong guarantee for ensuring food safety. Conventional chromatographic-based or mass spectrum methods, which rely on bulky instrument and skilled personnel, are not suitable for on-site surveillance. By contrast, visual detections which possess the merits of rapidity and sophisticated instrument-free present an excellent potential for the on-site detection of AFs. This review intends to summarize the latest development of visual methods for AFs detection, including paper-based tests, chromogenic reactions, and luminescent methods. Emerging technologies, like nanotechnology, DNAzymes, and aptamers combined with these visual methods are introduced. The basic principles, features, and application advantages of each type of visual methods are discussed. The biggest challenges and perspectives on their future trends are also addressed.

An overview of nanomaterial based biosensors for detection of Aflatoxin B1 toxicity in foods

Aflatoxin B1 (AFB1) is one of the most potent mycotoxin contaminating several foods and feeds. It suppresses immunity and consequently increases mutagenicity, carcinogenicity, teratogenicity, hepatotoxicity, embryonic toxicity and increasing morbidity and mortality. Continuous exposure of AFB1 causes liver damage and thus increases the prevalence of cirrhosis and hepatic cancer. This article was planned to provide understanding of AFB1 toxicity and provides future directions for fabrication of cost effective and user-friendly nanomaterials based analytical devices. In the present article various conventional (chromatographic & spectroscopic), modern (PCR & immunoassays) and nanomaterials based biosensing techniques (electrochemical, optical, piezoelectrical and microfluidic) are discussed alongwith their merits and demerits. Nanomaterials based amperometric biosensors are found to be more stable, selective and cost-effective analytical devices in comparison to other biosensors. But many unresolved issues about their stability, toxicity and metabolic fate needs further studies. In-depth studies are needed for development of advanced nanomaterials integrated biosensors for specific, sensitive and fast monitoring of AFB1 toxicity in foods. Integration of biosensing system with micro array technology for simultaneous and automated detection of multiple AFs in real samples is also needed. Concerted efforts are also required to reduce their possible hazardous consequences of nanomaterials based biosensors.

Aptamer-based detection of fumonisin B1: A critical review

Mycotoxin contamination is a current issue affecting several crops and processed products worldwide. Among the diverse mycotoxin group, fumonisin B1 (FB1) has become a relevant compound because of its adverse effects in the food chain. Conventional analytical methods previously proposed to quantify FB1 comprise LC-MS, HPLC-FLD and ELISA, while novel approaches integrate different sensing platforms and fluorescently labelled agents in combination with antibodies. Nevertheless, such methods could be expensive, time-consuming and require experience. Aptamers (ssDNA) are promising alternatives to overcome some of the drawbacks of conventional analytical methods, their high affinity through specific aptamer-target binding has been exploited in various designs attaining favorable limits of detection (LOD). So far, two aptamers specific to FB1 have been reported, and their modified and shortened sequences have been explored for a successful target quantification. In this critical review spanning the last eight years, we have conducted a systematic comparison based on principal component analysis of the aptamer-based techniques for FB1, compared with chromatographic, immunological and other analytical methods. We have also conducted an in-silico prediction of the folded structure of both aptamers under their reported conditions. The potential of aptasensors for the future development of highly sensitive FB1 testing methods is emphasized.

An enhanced enzyme-linked aptamer assay for the detection of zearalenone based on gold nanoparticles

A novel enhanced enzyme-linked aptamer assay (ELAA) for the detection of zearalenone (ZEN) was developed based on gold nanoparticles (AuNPs) modified with an aptamer and horseradish peroxidase (HRP). In this assay, the aptamer was used as a recognition probe to competitively bind with coated ZEN-BSA on a microplate and ZEN in samples. AuNPs with high surface areas were used as a carrier to immobilize more amounts of HRP labelled aptamer probe, which can amplify the colorimetric signal by enhancing catalysis of the HRP enzyme compared with the traditional enzyme-linked method. Under the optimal conditions, the enhanced ELAA presented a good linearity in the range of 0.1-160 ng mL-1 and the limit of detection was 0.08 ng mL-1 for ZEN detection. In addition, the enhanced ELAA had no cross reactivity with other mycotoxins and showed good recoveries in spiked corn oil samples. These results indicated that the AuNP enhanced ELAA provided a new approach with simplicity, and high sensitivity and specificity for the detection of ZEN in foodstuff.

Aptasensors for mycotoxin detection: A review

Mycotoxins are toxic compounds produced by fungi, which represent a risk to the food and feed supply chain, having an impact on health and economies. A high percentage of feed samples have been reported to be contaminated with more than one type of mycotoxin. Systematic, cost-effective and simple tools for testing are critical to achieve a rapid and accurate screening of food and feed quality. In this review, we describe the various aptamers that have been selected against mycotoxins and their incorporation into optical and electrochemical aptasensors, outlining the strategies exploited, highlighting the advantages and disadvantages of each approach. The review also discusses the different materials used and the immobilization methods employed, with the aim of achieving the highest sensitivity and selectivity.

Development of nucleic acid aptamer-based lateral flow assays: A robust platform for cost-effective point-of-care diagnosis

Lateral flow assay (LFA) has made a paradigm shift in the in vitro diagnosis field due to its rapid turnaround time, ease of operation and exceptional affordability. Currently used LFAs predominantly use antibodies. However, the high inter-batch variations, error margin and storage requirements of the conventional antibody-based LFAs significantly impede its applications. The recent progress in aptamer technology provides an opportunity to combine the potential of aptamer and LFA towards building a promising platform for highly efficient point-of-care device development. Over the past decades, different forms of aptamer-based LFAs have been introduced for broad applications ranging from disease diagnosis, agricultural industry to environmental sciences, especially for the detection of antibody-inaccessible small molecules such as toxins and heavy metals. But commercial aptamer-based LFAs are still not used widely compared with antibodies. In this work, by analysing the key issues of aptamer-based LFA design, including immobilization strategies, signalling methods, and target capturing approaches, we provide a comprehensive overview about aptamer-based LFA design strategies to facilitate researchers to develop optimised aptamer-based LFAs.