Competitive Lateral Flow Immunoassay Research Articles

Modular Point-of-Need Tropane Alkaloid Detection at Regulatory Levels: Combining Solid-Liquid Extraction from Buckwheat with a Paper-Immobilized Liquid-Phase Microextraction and Immuno-Detection in Interconnectable 3D-Printed Devices.

Contamination with tropane alkaloids in cereals is expected to increase globally. However, current identification tools (e.g., liquid chromatography-mass spectrometry) for tropane alkaloids are time-consuming and expensive. Furthermore, their miniaturized alternatives lack sensitivity and robustness. Therefore, there is a pressing need for inexpensive and effective screening methods. Here, an on-site applicable modular workflow for tropane alkaloid detection in buckwheat is presented. The modular workflow combines paper microfluidics and interconnectable 3D-printed sample preparation tools and was evaluated for different tropane alkaloids, including atropine and scopolamine. Furthermore, integration with an indirect competitive lateral flow immunoassay (icLFIA) for atropine detection at relevant levels was demonstrated. In the modular workflow, to minimize matrix coextraction, tropane alkaloids were extracted from the milled buckwheat cereals by a mixture of alkaline aqueous and immiscible organic solvents (extraction recoveries: 66-79%). The tropane alkaloids were subsequently concentrated with a newly developed paper-immobilized liquid-phase microextraction (PI-LPME, extraction recoveries: 34-60%, concentration factor to immobilized solution in paper: 60-108×). After the PI-LPME, with an integrated 3D-printed setup, the tropane alkaloids were directly eluted (elution recoveries: 83-93%) and detected with the icLFIA. Digital read-out of the icLFIA, by employing a hand-held reader, enabled semiquantification of atropine (IC50 = 0.56 ng mL-1 in standard solutions). The modular workflow was validated by analyzing 24 blank and spiked buckwheat cereal samples with 5 and 10 μg kg-1 atropine. A cutoff value was established with an estimated false negative rate of 1% and estimated false positive rate of 0.68%. Therefore, the modular workflow can aid in fast, inexpensive, and on-site atropine detection by nonexperts, and when integrated with a scopolamine-specific icLFIA expanded toward scopolamine detection. Moreover, the developed sample extraction and concentration method (PI-LPME) is suitable for the analysis of many other compounds with pH-dependent polarity.

B-262 Validation of a point-of-care lateral flow immunoassay for urine drug testing prior to application in an outpatient rapid access addiction medicine clinic

Abstract Background Point-of-care (POC) urine drug testing is a useful adjunct to self-reporting in rapid access addiction medicine settings to immediately guide patient management. However, available POC immunoassays have limitations including cross-reactivity with unrelated compounds or low sensitivity that may cause false results. Here, we assessed the performance of a multi-drug test panel by comparing against gold-standard liquid chromatography tandem mass spectrometry (LC-MS/MS) testing. Methods 102 residual urine specimens were assayed using a competitive lateral flow immunoassay (LFA) for 10 drugs: 2-ethylene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP, methadone metabolite), buprenorphine, morphine, hydromorphone, oxycodone, fentanyl, cocaine, methamphetamine, amphetamine, and benzodiazepines (BTNX Rapid ResponseTM Multi-Drug Panel). Results were compared to those obtained by LC-MS/MS (n=67, 66%) or kinetic interaction of microparticles in solution automated immunoassay (KIMS) (Roche Diagnostics, n=35, 33%). Broad spectrum LC-MS/MS results were reviewed in entirety for discordant cases, particularly in false positives to identify the presence of any known cross-reacting compounds. Results Of 10 drugs evaluated, four demonstrated ≥95% agreement with LC-MS/MS or KIMS immunoassay (EDDP, buprenorphine, oxycodone, methamphetamine). Fentanyl demonstrated the highest false negative rate of 44% (LFA cut-off: 10 ng/mL) followed by amphetamines (22%, cut-off: 1000 ng/mL). Morphine and hydromorphone demonstrated false positive rates of 14% and 18%, respectively, with most cases likely due to cross-reacting opiate or opioid metabolites. Benzodiazepines (target: Oxazepam) demonstrated false positive and negative rates of 13% and 24%, respectively. Conclusions To our knowledge, this is the first study to evaluate the performance of the BTNX multi-drug test panel against definitive testing in urine samples. While good concordance was observed for most drugs, high rates of discordant results for fentanyl and others emphasize the need for confirmatory testing by methods with higher sensitivity and specificity. Careful consideration prior to implementation would be essential, including physician education, interpretative comments, and training resources.

Research on the Flow Characteristics and Reaction Mechanisms of Lateral Flow Immunoassay under Non-Uniform Flow.

Lateral flow immunoassay (LFIA) is extensively utilized for point-of-care testing due to its ease of operation, cost-effectiveness, and swift results. This study investigates the flow dynamics and reaction mechanisms in LFIA by developing a three-dimensional model using the Richards equation and porous media transport, and employing numerical simulations through the finite element method. The study delves into the transport and diffusion behaviors of each reaction component in both sandwich LFIA and competitive LFIA under non-uniform flow conditions. Additionally, the impact of various parameters (such as reporter particle concentration, initial capture probe concentrations for the T-line and C-line, and reaction rate constants) on LFIA performance is analyzed. The findings reveal that, in sandwich LFIA, optimizing parameters like increasing reporter particle concentration and initial capture probe concentration for the T-line, as well as adjusting reaction rate constants, can effectively enhance detection sensitivity and broaden the working range. Conversely, in competitive LFIA, the effects are inverse. This model offers valuable insights for the design and enhancement of LFIA assays.

Au@Ag Core-Shell Nanoparticles for Colorimetric and Surface-Enhanced Raman-Scattering-Based Multiplex Competitive Lateral Flow Immunoassay for the Simultaneous Detection of Histamine and Parvalbumin in Fish.

Foodborne allergies and illnesses represent a major global health concern. In particular, fish can trigger life-threatening food allergic reactions and poisoning effects, mainly caused by the ingestion of parvalbumin toxin. Additionally, preformed histamine in less-than-fresh fish serves as a toxicological alert. Consequently, the analytical assessment of parvalbumin and histamine levels in fish becomes a critical public health safety measure. The multiplex detection of both analytes has emerged as an important issue. The analytical detection of parvalbumin and histamine requires different assays; while the determination of parvalbumin is commonly carried out by enzyme-linked immunosorbent assay, histamine is analyzed by high-performance liquid chromatography. In this study, we present an approach for multiplexing detection and quantification of trace amounts of parvalbumin and histamine in canned fish. This is achieved through a colorimetric and surface-enhanced Raman-scattering-based competitive lateral flow assay (SERS-LFIA) employing plasmonic nanoparticles. Two distinct SERS nanotags tailored for histamine or β-parvalbumin detection were synthesized. Initially, spherical 50 nm Au@Ag core-shell nanoparticles (Au@Ag NPs) were encoded with either rhodamine B isothiocyanate (RBITC) or malachite green isothiocyanate (MGITC). Subsequently, these nanoparticles were bioconjugated with anti-β-parvalbumin and antihistamine, forming the basis for our detection and quantification methodology. Additionally, our approach demonstrates the use of SERS-LFIA for the sensitive and multiplexed detection of parvalbumin and histamine on a single test line, paving the way for on-site detection employing portable Raman instruments.

Dual-color MoS2@QD nanosheets mediated dual-mode lateral flow immunoassay for flexible and ultrasensitive detection of multiple drug residues

The sensitive on-site monitoring of multiple agricultural drugs in complex real media is critical to human health but remains a challenge. In this paper, we reported the design of film-like dual-mode nanolabel (MTQD), using molybdenum disulfide (MoS2) nanosheet-loaded numerous quantum dots (QDs) to generated co-enhanced colorimetric-fluorescence signals, and demonstrated its powerful capabilities in competitive lateral flow immunoassay (LFA) for flexible, ultrasensitive, and multiplex detection of four kinds of common agricultural drugs. Three layers of red and green QDs were continuously coated onto the surface of MoS2 to suppress the inner filter effect of two-dimensional nanomaterials effectively and greatly improve the specificity of the LFA system for multitarget analysis. The dual-mode LFA combined with a low-cost dual-fluorescence reading instrument can flexibly and simultaneously monitor two pesticides (clothianidin, carbendazim) and two veterinary drugs (kanamycin, chloramphenicol) in complex food and experimental samples with low detection limits of 0.1 ng/mL level in the observation of colorimetric signals and showed at least a 46-fold improvement in sensitivity in the sensing of fluorescence signals. This colorimetric dual-fluorescence platform greatly broadens the application range of existing LFA techniques without increasing testing time, thus showing great application prospects for the point-of-care testing of small-molecule pollutants in different situations.

Lateral Flow Immunoassay Based on Quantum-Dot Nanobeads for Detection of Chloramphenicol in Aquatic Products.

Quantum dot nanobeads (QBs) were used as signal source to develop competitive lateral flow immunoassay (LFIA) for the detection of chloramphenicol (CAP). The quantitative detection of CAP was achieved by calculating the total color difference (∆E) values of the test line (T line) using the images of test strips. QB-based LFIA (QBs-LFIA) allowed the effective dynamic linear detection of CAP in the range of 0.1-1.5 ng/mL. The limit of detection (LOD) was 3.0 ng/mL, which was 50 and 667 times lower than those achieved for two different brands of colloidal gold kits. The recoveries of CAP during real-sample detection were 82.82-104.91% at spiked levels of 0.1, 0.7, and 1.5 ng/mL. These results indicate that the developed QBs-LFIA facilitates the sensitive detection of CAP.

Enhanced Lateral Flow Immunoassay with Double Competition and Two Kinds of Nanoparticles Conjugates for Control of Insecticide Imidacloprid in Honey.

Finding optimal conditions for competitive lateral flow immunoassay is a controversial task. The content of specific antibodies labeled by nanoparticles should be simultaneously high to reach intense signals and low to register an influence on the signals for minimal concentrations of the target analyte. We propose to use two kinds of complexes of gold nanoparticles in the assay, with antigen-protein conjugates and with specific antibodies. The first complex interacts both with immobilized antibodies in the test zone and with antibodies on the surface of the second complex. In this assay, the coloration is enhanced by the binding of two-colored preparations in the test zone, whereas the antigen in the sample inhibits both the binding of the first conjugate with the immobilized antibodies and with the second conjugate. This approach is realized for the detection of insecticide imidacloprid (IMD), an important toxic contaminant connected with the recent global death of bees. The proposed technique expands the working range of the assay, that is, in accordance with its theoretical analysis. The reliable change of coloration intensity is achieved for a 2.3-times-lower concentration of the analyte. The limit of IMD detection is 0.13 ng/mL for tested solutions and 1.2 µg/kg for initial honey samples. The combination of two conjugates doubles the coloration in the absence of the analyte. The developed lateral flow immunoassay is applicable for five-fold-diluted honey samples without extraction, does not require additional stages (all reagents are pre-applied to the test strip), and is implemented in 10 min.

Ultrasensitive Lateral Flow Immunoassay for Fumonisin B1 Detection Using Highly Luminescent Aggregation-Induced Emission Microbeads

Lateral flow immunoassay (LFIA) based on fluorescent microbeads has attracted much attention for its use in rapid and accurate food safety monitoring. However, conventional fluorescent microbeads are limited by the aggregation-caused quenching effect of the loaded fluorophores, thus resulting in low signal intensity and insufficient sensitivity of fluorescent LFIA. In this study, a green-emitting fluorophore with an aggregation-induced emission (AIE) characteristic was encapsulated in polymer nanoparticles via an emulsification technique to form ultrabright fluorescent microbeads (denoted as AIEMBs). The prepared AIEMBs were then applied in a competitive LFIA (AIE-LFIA) as signal reporters for the rapid and highly sensitive screening of fumonisin B1 (FB1) in real corn samples. High sensitivity with a detection limit of 0.024 ng/mL for FB1 was achieved by the developed AIE-LFIA. Excellent selectivity, good accuracy, and high reliability of the AIE-LFIA were demonstrated, indicating a promising platform for FB1 screening.

Multiplexed lateral flow immunoassay based on inner filter effect for mycotoxin detection in maize

Multiplexed screening techniques for simple, rapid, and accurate mycotoxin sensing are of great importance. Hence, a multiplexed competitive lateral flow immunoassay (cLFIA) based on inner filter effect (IFE) between flower-like gold nanoparticles and red-emitting quantum dots was developed for the simultaneous detection of aflatoxin B1 (AFB1), ochratoxin A (OTA), and zearalenone (ZEN) in maize. A control line based on a biotin–streptavidin system was developed to ensure that a target independent signal can serve as the reference signal and achieve accurate quantification of multiple targets. The resultant multiplexed IFE–cLFIA test strips exhibited high sensitivities for AFB1, OTA, and ZEN, with LODs of 0.005, 0.04, and 0.4 μg/L, respectively. The quantitative detection linear range was 0.01–0.625 μg/L for AFB1, 0.08–2.5 μg/L for OTA, and 0.8–25 μg/L for ZEN in the diluted maize extract solution. Recoveries for the three kinds of mycotoxins in maize ranged from 72.92% to 105.80%, with a coefficient of variation below 15.43%.

Ultrasensitive Competitive Lateral Flow Immunoassay with Visual Semiquantitative Inspection and Flexible Quantification Capabilities

Antibiotics abuse has caused various problems threatening human health and ecological environment. Monitoring antibiotics residual levels is of great significance, yet still challenging for quantitative point-of-need testing with high-sensitivity and visual capability. Here we developed a competitive lateral flow immunoassay (CLFIA) platform with flexible readout for enrofloxacin (ENR), a regularly added antibiotic. To overcome the limitation of low sensitivity of traditional colloidal gold-based CLFIA, the three-dimensionally assembled gold nanoparticles (AuNPs) within dendritic silica scaffold were fabricated as signal reporters. The assembly structure effectively retained the intrinsic absorption features of hydrophobic AuNPs and greatly enhanced the light extinction ability of a single label for signal amplification. The obtained CLFIA strips can not only achieve qualitative screening of ENR at a very low concentration by naked eye (cutoff value: 0.125 ng/mL), but also enable ultrasensitive quantification of ENR by an optical scanner (limit of detection: 0.00195 ng/mL) or a smartphone (limit of detection: 0.0078 ng/mL). Moreover, to elaborate the visual inspection degree of CLFIA against traditional yes/no interpretation, a novel multirange gradient CLFIA strip was prepared for visually semiquantitative identification of ENR with four concentration ranges. The novel CLFIA platform demonstrated sensitive, specific, and reliable determination of ENR with flexible signal readout and provides a potential and invigorating pathway to point-of-need immunoassay of antibiotics.

CD8 cell counting in whole blood by a paper-based time-resolved fluorescence lateral flow immunoassay

The number of CD8+ T lymphocytes (CD8 cells) in peripheral blood can directly reflect the immune status of the body and is widely used for auxiliary diagnosis and prognostic evaluation of diseases. There is an urgent need to develop a simple CD8 cell-counting platform to meet clinical needs. Our group designed a paper-based cell-counting method based on a blocking competition strategy. In addition, we developed a time-resolved fluorescence-blocking competitive lateral flow immunoassay (TRF-BCLFIA) for point-of-care CD8 cell counting that functions by measuring europium nanoparticle (EuNP)-labeled CD8 antibody probes that are not captured by CD8 cells, and we indirectly calculated the concentration of CD8 cells in samples. Within 30 min, four operation steps can provide an accurate CD8 cell count for a 75-μL whole-blood sample, and this approach can be implemented on a handheld device. The TRF-BCLFIA reliably quantified CD8 cells in whole-blood samples, in which the assay exhibited a linear correlation (R2 = 0.989) readout for CD8 cell concentrations ranging from 137 to 821 cells/μL. To validate this approach, our newly developed CD8 cell-counting tool was used to assess 33 tumor patient blood samples. The results showed a high consistency with a flow cytometry-based absolute count. This analysis approach is a promising alternative for the costly standard flow cytometry-based tools for CD8 cell counting in tumor patients in community clinics, small hospitals, and low medical resource regions. This technology would deliver simple diagnostics to patients anywhere in the world, regardless of geography or socioeconomic status.

Adulteration of cow’s milk with buffalo’s milk detected by an on-site carbon nanoparticles-based lateral flow immunoassay

A competitive lateral flow immunoassay using amorphous carbon nanoparticles (CNPs) and non-immunoglobulin antigen has been developed for the rapid detection of adulteration of cow’s milk with buffalo’s milk. Purified polyclonal antibodies against a specific buffalo's milk protein fraction were conjugated to CNPs and sprayed on a conjugate pad. The test line consisted of buffalo's skimmed milk proteins (1.6 μg/cm), while the control line contained anti-rabbit antibodies raised in goat (0.5 μg/cm). In the test procedure milk sample is mixed with 100 mM borate buffer (pH 8.8 containing 1% BSA and 0.05% Tween 20) and pipetted onto the sample-cum-conjugate pad. A black/grey test line can be observed if the sample is free from buffalo's milk. The sensitivity of the test i.e. no visible test line is 5% adulteration of cow's milk with buffalo's milk. The test has applicability at the milk receiving stations and can be applied to heated milk samples.

An accurate and amplifying competitive lateral flow immunoassay for the sensitive detection of haptens

ABSTRACTWe report a new competitive lateral flow immunoassay (LFIA) for hapten detection, which uses antibodies to bind antigens from a sample and form a coloured immune complex due to artificial antigens conjugated with gold nanoparticles; these were intercepted with SPA. Here, 2,4-dichlorophenoxyacetic acid (2,4-D) and gentamicin (GM) were selected as model analytes. The visual limit of detection of the 2,4-D strip was 25 ng/mL in tap water; the GM strip was 3.13 ng/mL in milk. This approach exhibits more than a 40-fold lower detection limit for 2,4-D and 3.2-fold lower for GM, which is compared to traditional LFIA using the same reagents. This approach can accurately control the amount of antibody, protect the activity of antibody and enhance the detection signal, thus improving the sensitivity of the LFIA and providing more and more sensitive methods for the development of LFIAs.HighlightsThis study developed a new method of LFIA that could improve the sensitivity of LFIA without adding any reagent.The antibodies are unlabelled; thus, the immunological properties of the antibodies are not destroyed by antibody folding during the labelling process.Sufficient gold-labelled antigens ensure that each antibody bound to the test line can combine two gold nanoparticles, thereby amplifying the overall signal.

A Comparative Study of Approaches to Improve the Sensitivity of Lateral Flow Immunoassay of the Antibiotic Lincomycin.

This study provides a comparative assessment of the various nanodispersed markers and related detection techniques used in the immunochromatographic detection of an antibiotic lincomycin (LIN). Improving the sensitivity of the competitive lateral flow immunoassay is important, given the increasing demands for the monitoring of chemical contaminants in food. Gold nanoparticles (AuNPs) and CdSe/ZnS quantum dots (QDs) were used for the development and comparison of three approaches for the lateral flow immunoassay (LFIA) of LIN, namely, colorimetric, fluorescence, and surface-enhanced Raman spectroscopy (SERS)-based LFIAs. It was demonstrated that, for colorimetric and fluorescence analysis, the detection limits were comparable at 0.4 and 0.2 ng/mL, respectively. A SERS-based method allowed achieving the gain of five orders of magnitude in the assay sensitivity (1.4 fg/mL) compared to conventional LFIAs. Therefore, an integration of a SERS reporter into the LFIA is a promising tool for extremely sensitive quantitative detection of target analytes. However, implementation of this time-consuming technique requires expensive equipment and skilled personnel. In contrast, conventional AuNP- and QD-based LFIAs can provide simple, rapid, and inexpensive point-of-care testing for practical use.

An innovative prussian blue nanocubes decomposition-assisted signal amplification strategy suitable for competitive lateral flow immunoassay to sensitively detect aflatoxin B1

A prussian blue nanocubes decomposition-assisted signal amplification strategy for competitive lateral flow immunoassay (PBNCD-SALFIA) was innovatively proposed to analyze aflatoxin B1 (AFB1) in foodstuffs. The signal was amplified on account of the PBNCs can degrade and fade under alkaline condition, which could weak the color of the test- and control-lines, thereby improving the sensitivity of the sensor. The strategy was technically-simple, just using NaOH as an amplifier can realize signal amplification in the competition assay. Under optimized conditions, the enhanced strip exhibited excellent specificity and sensitivity in AFB1 monitoring with a detection limit of 23 pg/mL, which was approximately 4- and 8-folds lower than those of PBNCs-LFIA (90 pg/mL) and conventional gold nanoparticles-LFIA (175 pg/mL), respectively. Taking the advantage of the color-fading, this platform revealing the lowest detectable concentration of 0.184, 0.368 and 0.184 μg/kg for AFB1 in corn, peanut and pumpkin seed within 58 min, separately, showing reliable results.

A Fluorescent Sensor-Assisted Paper-Based Competitive Lateral Flow Immunoassay for the Rapid and Sensitive Detection of Ampicillin in Hospital Wastewater.

In this study, a convenient assay method has been developed based on labeled functional nucleic acids (H-DNA) and a competitive fluorescent lateral flow immunoassay (CF-LFI) for ampicillin (AMP) detection. Herein, we designed the tunable AMP probes for AMP detection based on the AMP aptamer, and the secondary DNA fragment. The probes can generate tunable signals on the test line (T line) and control line (C line) according to the concentration of AMP. The accuracy of detection was improved by optimizing the tunable AMP probes. Under the optimal conditions, the linear concentration of AMP detection is ranged from 10 to 200 ng/L with a limit of quantitation (LOQ) value of 2.71 ng/L, and the recovery is higher than 80.5 %. Moreover, the developed method shows the potential application for AMP detection in the hospital wastewater.

Development of an IgY-based lateral flow immunoassay for detection of fumonisin B in maize.

Fumonisin is one of the most prevalent mycotoxins in maize, causing substantial economic losses and potential health risks in human and animals. In the present study, in-house polyclonal IgY antibody against fumonisin group B (FB) was applied for the development of a competitive lateral flow immunoassay detecting these mycotoxins in maize grains with the limit of detection of 4000 µg/kg, which corresponds to the maximum residue limit adopted by The International Codex Alimentarius Commission. To this end, factors affecting the test performance including nitrocellulose membrane type, dilution factor of maize homogenates in running buffer, amount of detection conjugate, and incubation time between detection conjugate and samples were optimized. Under the optimal condition (UniSart ®CN140 nitrocellulose membrane, FB 1-BSA immobilized at 1 µg/cm, 1:10 dilution factor, 436 ng of gold nanoparticle conjugate, 30 minutes of incubation), the developed test could detect both FB 1 and FB 2 in maize with limit of detection of 4000 µg/kg, and showed no cross-reactivity to deoxynivalenol, ochratoxin A, aflatoxin B1 and zearalenone. When applied to detect FB 1 and FB 2 in naturally contaminated maize samples, results obtained from the developed assay were in good agreement with those from the high-performance liquid chromatography method. This lateral flow immunoassay is particularly suitable for screening of fumonisins in maize because of its simplicity and cost-effectiveness.

Development of an IgY-based lateral flow immunoassay for detection of fumonisin B in maize

Fumonisin is one of the most prevalent mycotoxins in maize, causing substantial economic losses and potential health risks in human and animals. In the present study, in-house polyclonal IgY antibody against fumonisin group B (FB) was applied for the development of a competitive lateral flow immunoassay detecting these mycotoxins in maize grains with the limit of detection of 4000 µg/kg, which corresponds to the maximum residue limit adopted by The International Codex Alimentarius Commission. To this end, factors affecting the test performance including nitrocellulose membrane type, dilution factor of maize homogenates in running buffer, amount of detection conjugate, and incubation time between detection conjugate and samples were optimized. Under the optimal condition (UniSart®CN140nitrocellulose membrane, FB1-BSA immobilized at 1 µg/cm, 1:10 dilution factor, 436 ng of gold nanoparticle conjugate, 30 minutes of incubation), the developed test could detect both FB1and FB2in maize with limit of detection of 4000 µg/kg, and showed no cross-reactivity to deoxynivalenol, ochratoxin A, aflatoxin B1 and zearalenone. When applied to detect FB1and FB2in naturally contaminated maize samples, results obtained from the developed assay were in good agreement with those from the high-performance liquid chromatography method. This lateral flow immunoassay is particularly suitable for screening of fumonisins in maize because of its simplicity and cost-effectiveness.

Rapid detection of cow milk adulteration/contamination in goat milk by a lateral flow colloidal gold immunoassay strip.

Current available methods to detect cow milk adulteration or accidental contamination of goat milk are both laborious and time consuming. The aim of this technical research communication was to develop a simple, rapid, specific and sensitive method for quantitative detection of cow milk in goat milk. A competitive lateral flow immunoassay (LFIA) strip was developed using a specific monoclonal antibody (mAb) labeled with colloidal gold nanoparticles (GNPs) for specifically binding to cow milk casein. The detection limit of this rapid detection was 0.07% of cow milk in goat milk, providing equal specificity and higher sensitivity when compared with a commercial enzyme-linked immunosorbent assay (ELISA). These result suggest that the established rapid GNPs-LFIA strip could be used for monitoring cow milk adulteration/contamination of goat milk.

Aggregation-induced emission-based competitive lateral flow immunoassay for rapid detection of sulfamethazine in honey

ABSTRACTSulfamethazine (SMZ), widely used for disease prevention of bees, is harmful to consumers when excess SMZ residues are present in honey. In this study, a novel competitive lateral flow immunoassay (LFIA) was established by using aggregation-induced emission fluorescent microsphere (AIEFM) as label for the detection of SMZ. Results indicated that the limit of detection (LOD) for the developed competitive AIEFM-LFIA in honey was 0.028 ng/mL, and the corresponding linear range was 0.05−5 ng/mL. Recovery experiments showed that the average recovery range was 75.6–95.1% with coefficient variations of 5.7–12.9% in honey. The developed competitive AIEFM-LFIA was compatible with HPLC-MS/MS in detecting SMZ in 15 real samples from honey. In general, the proposed AIEFM-LFIA is well suited for the competitive format and has great potential for the detection of other small targets with single antigenic site in practical application.