NC Membrane Research Articles

Strategic reuse of rapid antigen tests for coagulation status assessment: an integrated machine learning approach

Addressing the pressing demand for rapid and inexpensive coagulation testing in cardiovascular care, this study introduces a novel application of repurposed COVID-19 rapid antigen tests (RATs) as paper-based lateral flow assays (LFAs) combined with machine learning for coagulation status evaluation. By further developing a mobile app prototype, we present a platform that enables clinicians to perform immediate and accurate anticoagulant dosing adjustments using existing post-pandemic resources. Our proof-of-concept employs a random forest machine learning classifier to interpret image feature variations on RAT NC membrane, correlating red blood cell (RBC) wicked diffusion distance in recalcified citrated whole blood with changes in coagulative viscosity, easily interpreted. Enhanced by confocal imaging studies of paper microfluidics, our approach provides insights into the mechanisms dissecting coagulation components, achieving high classification precision, recall, and F1-scores. The inverse relationship between RBC wicked diffusion distance and enoxaparin concentration paves the way for machine learning to inform real-time dose prescription adjustments, aligning with individual patient profiles to optimize therapeutic outcomes. This study not only demonstrates the potential of leveraging surplus RATs for coagulation management but also exemplifies a cost-effective, rapid, and smart strategy to enhance clinical decision-making in the post-pandemic era.Graphical

Development of highly sensitive dual-enhanced fluorescence quenching immunochromatographic test strips based on Pt nanoprobes

The fluorescence-quenching method is crucial in vitro analysis, particularly for immunochromatographic test strips (ICTs) using noble metal nanoparticles as probes. However, ICTs still fall short in meeting the requirements for the detection of traces biomarkers due to the noble metal nanoparticles can only quench fluorescence of the dyes within a confined distance. Interestingly, noble metal nanoparticles, such as Pt NPs cannot only perform fluorescence-quenching ability based on the Förster resonance energy transfer (FRET), but also show perfect oxidase-like catalytic performance on many kinds of substrates, such as 3,3’,5,5’ -tetramethylbenzidine (TMB). We observed that the oxTMB (the oxidation products of TMB) exhibited notable effectiveness in quenching Cy5 fluorescence by the strong inner filter effect (IFE), which obviously improved the fluorescence-quenching efficiency with extremely low background signal. Through the dual-enhanced fluorescence quenching mechanism, the fluorescence quenching constant (Kn) was 661.24-fold that of only Pt NPs on the NC membrane. To validate the feasibility of this technique, we employed two types of biomarkers, namely microRNA (miR-15a-5p) and the signature protein (PSA). The sensitivity of miR-15a-5p was 9.286 × 10−18 mol/L and 17.5-fold more than that based on Pt NPs. As for the PSA, the LOD (0.6265 pg/mL) was 15.5-fold enhancement more sensitive after catalysis. Overall, the dual-enhanced fluorescence quenching rFICTs could act as a practical detection for biomarker in real samples.

A versatile upconversion-based multimode lateral flow platform for rapid and ultrasensitive detection of microRNA towards health monitoring

MicroRNAs are small single-stranded RNA molecules associated with gene expression and immune response, suggesting their potential as biomarkers for health monitoring. Herein, we designed a novel upconversion-based multimode lateral flow assay (LFA) system to detect microRNAs in body fluids by simultaneously producing three unique signals within a detection strip. The core-shell Au-DTNB@Ag nanoparticles act as both the Raman reporters and acceptors, quenching fluorescence from upconversion nanoparticles (UCNPs, NaYF4: Yb3+, Er3+) via the Förster resonance energy transfer mechanism. Using microRNA-21 as a representative analyte, the LFA system offers remarkable detection range from 2 nM to 1 fM, comparable to outcomes from signal amplification methods, due to the successful single-layer self-assembly of UCNPs on the NC membrane, which greatly enhances both the convenience and sensitivity of the LFA technique. Additionally, our proprietary fluorescence-Raman detection platform simplifies result acquisition by reducing procedural intricacies. The biosensor, when evaluated with diverse bodily fluids, showed remarkable selectivity and sustained stability. Importantly, our LFA biosensor effectively identified periodontitis and lung cancer patients from healthy subjects in genuine samples, indicating significant potential for disease prediction, early diagnosis, and progression tracking. This system holds promise as a multifunctional tool for various biomarker assays.

Development of a new immunochromatographic strip mediated by colloidal Gold-MAb nanoparticles for rapid detection of subgroup K Avian leukemia virus

K subgroup of Avian leukemia virus (ALV-K), as the latest reported exogenous ALV subgroup, can cause severe immunosuppression and tumorigenesis in infected chickens and bring serious threats to the poultry. Culling the positive chickens from breeder flocks is the most effective measurement for controling its infection at present. To setup a specific and rapid method for detecting ALV-K, an immunochromatographic strip (ICS) based on colloidal gold nanoparticles and double monoclonal antibodies (MAbs) immunochemical reaction was successfully developed. The solution containing colloidal gold particles (colloidal 20 nm) was prepared by sodium citrate reduction, and the ascites MAbs against ALV-K were purified and identified. The antibody concentration of the colloidal gold-MAb complex reaction system was 9.6 μg/mL, and the optimum pH was 7.5. The optimum coating concentrations of the captured antibody and quality control antibody on the NC membrane were 1.2 mg/mL and 0.6 mg/mL, respectively. The results showed that the prepared ICS could specifically detect ALV-K and had no cross reaction with exogenous ALV-A/B/J strains. Its sensitivity was 64 TCID50/mL against ALV-K and 0.25 μg/mL against ALV-K gp85 protein. The ICS stored at 4 °C for 180 d, at 25 °C for 45 d, and at 37 °C for 15 d could stably detect ALV-K in the samples. In comparision detection of 128 clinical samples, the coincidence rates in cloacal swab samples, serum samples, egg albumen samples and tissue homogenate samples between the ICS and the commercial ALV p27 antigen ELISA kit were 100 %, 100 %, 96.7 % and 96.9 %, respectively; moreover, the prepared ICS in operations was simpler and more convenient. This study supplies a new specific and rapid method for detecting ALV-K in clinics. This is the first report on the application of nano-colloidal gold ICS in ALV-K differential detection.

An Aptamer-Based Lateral Flow Biosensor for Low-Cost, Rapid and Instrument-Free Detection of Ochratoxin A in Food Samples.

In this work, a simple and cost-efficient aptasensor strip is developed for the rapid detection of OTA in food samples. The biosensor is based on the lateral flow assay concept using an OTA-specific aptamer for biorecognition of the target analyte. The strip consists of a sample pad, a conjugate pad, a nitrocellulose membrane (NC) and an absorbent pad. The conjugate pad is loaded with the OTA-specific aptamer conjugated with gold nanoparticles (AuNPs). The test line of the NC membrane is loaded with a specific OTA-aptamer probe and the control line is loaded with a control probe. The assay is based on a competitive format, where the OTA present in the sample combines with the OTA aptamer-AuNP conjugate and prevents the interaction between the specific probe immobilized on the test line and the OTA aptamer-AuNP conjugates; therefore, the color intensity of the test line decreases as the concentration of OTA in the sample increases. Qualitative detection of OTA is performed visually, while quantification is performed by reflectance colorimetry using a commercial scanner and image analysis. All the parameters of the assay are investigated in detail and the analytical features are established. The visual limit of detection (LOD) of the strip is 0.05 ng mL-1, while the LOD for semi-quantitative detection using reflectance colorimetry is 0.02 ng mL-1. The lateral flow strip aptasensor is applied to the detection of OTA in wine, beer, apple juice and milk samples with recoveries in the range from 91 to 114%. The assay exhibits a satisfactory selectivity for OTA with respect to other mycotoxins and lasts 20 min. Therefore, the lateral flow strip aptasensor could be useful for the rapid, low-cost and fit-for-purpose on-site detection of OTA in food samples.

Establishment of a rapid method for detection of influenza A/B virus' antigens

This study aims to develop a rapid and convenient test card for simultaneous detection of influenza A and influenza B viruses using quantum dot-based immunochromatographic assay. The test card consists of a test strip and a plastic casing. The test strip is composed of absorbent paper, a buffer pad, nitrocellulose membrane (NC membrane), sample pad, quantum dot-labeled antibody pad, and polyvinyl chloride (PVC) board. The NC membrane is coated with mouse monoclonal antibodies against influenza A and influenza B viruses for the T lines (test lines), and reference proteins A and B for the C line (control line). The quantum dot-labeled antibody pad contains mouse monoclonal antibody-quantum dot conjugates against influenza A and influenza B viruses. The results showed that the detection limit of the test card for both viruses ranged from 1.51 ×102 to 2.71×103 TCID50/ml, indicating its sensitivity for accurate detection of influenza A and influenza B viruses without being affected by various variants. The test card exhibited specific reactions with different subtypes of influenza A and influenza B virus culture fluids and showed no cross-reactivity with adenovirus, novel coronavirus, Mycoplasma pneumoniae, respiratory syncytial virus, Staphylococcus aureus, and other pathogens. Overall, the sensitivity and specificity of the test card for simultaneous detection of influenza A and influenza B viruses meet the requirements for clinical use. It offers the advantages of simplicity, rapidity, and no requirement for special equipment, enabling quick auxiliary diagnosis to prevent disease transmission.

Rapid and accurate sensing platform based on lanthanide metal-organic framework and aptamer for Vibrio parahaemolyticus diagnosis

In this study, a rapid visual analysis strategy for pathogens was constructed based on lanthanide metal–organic frameworks (LnMOFs) and FAM-aptamer. The dual fluorescence signal changes were realized by the competitive binding effect of the target and LnMOFs on the FAM-aptamer. The nitrocellulose membrane (NC membrane) is used as the signal output platform, and the G/R value in Red, Green, Blue (RGB) of negative and positive signals is collected to output the detection results. Using Vibrio parahaemolyticus in seafood as model target, the detection performance of dual fluorescence sensing strategy was verified. Under the optimal conditions, the G/R difference between the positive and negative signals and the concentration of Vibrio parahaemolyticus was linear in the range of 102-105 colony forming units (CFU)/mL, and the detection limit was 102 CFU/mL. The method is simple to operate and the detection time can be controlled within 20 min. It can be developed as a portable detection kit, providing a new technical means for the safety and quality control of food supply chain.

Controlling the advancement of the liquid front of the nitrocellulose membrane assay under the influence of the centrifugal force on the Lab-on-a-Disc platform

Lateral flow immunoassays (LFIs) are ubiquitous point-of-care platforms for chemical and biological tests. They are widely used due to their portability, low cost, fast time of outcome, and absence of the need for presence of highly trained personnel to conduct these tests. One of the ways to enhance the sensitivity of LFIs is by slowing down the flow rate of the analyte through the active sensing area of the test strips (e.g., test line). Some recent developments towards the goal of the improvement of sensitivity of LFIs include placement of the lateral flow assays on the centrifugal microfluidic platforms (so-called Lab-on-discs) where the flow of the analyte through the lateral flow test strip could be sped up or impeded by the centrifugal force applied to the fluid passing through the lateral flow membrane. The finite element analysis (FEA) simulation is performed using ANSYS Fluent software platform and validated by the lateral flow membranes of several pore sizes, from 7 µm to 15 µm, were incorporated onto micromachined discs with integrated microfluidic networks with an accuracy of simulation to be within 15% of experimental values. The present work reports the dependence of the speed of advancement of the liquid meniscus of LFI placed on the Lab-on-a-Disc as a function of the porosity (volumetric fraction of the pores in nitrocellulose or NC membrane), pore sizes, and angular velocity of the spinning disc.

Quantitative injection strip platform using water-soluble paper and magnet based on a lateral flow assay.

Quantitative analysis for lateral flow immunoassay (LFA) strips was conducted continuously. Quantitative analysis means measuring concentration, which represents the number of molecules per unit volume. In this study, we designed a quantitative injection (QI) strip by modifying the structure of general LFA strips to inject the same unit volume. To achieve the injection of the same unit volume, we used water-soluble paper and magnet. In addition, the QI strip was fabricated to enable the physical separation of the gold conjugate pad from the nitrocellulose membrane (NC membrane) at the optimized time after sample injection. The optimized time refers to the time from the point at which the sample started flowing on the NC membrane to the point at which the strip was separated. At the samples of same concentration, the LFA strip increases detection signals as the volume of injected sample increases. In contrast to the LFA strip, the QI strip maintained consistent detection signals even with increasing volume of injected sample. Furthermore, the QI strip demonstrated an 11-fold lower deviation compared to the LFA strip. These results are attributed to the separation function of the QI strip. In conclusion, the QI strip is more suitable for quantitative analysis compared to the LFA strip due to the same unit volume without additional equipment such as a pipette. This study is expected to contribute to the development of user-friendly POCT and strip-based quantitative analysis.

Time-Lapse Electrochemical Impedance Detection of Bacteria Proliferation for Accurate Antibiotic Evaluation

Antibiotic detection includes direct detection and indirect detection. Indirect detection of antibiotic concentration reflected by the change of bacterial concentration is a more intuitive evaluation of antibiotic effect. It can not only accurately evaluate antibiotics, but also be used for tracking evaluation and analysis of antibacterial effects under long-term low-threshold levels. In this paper, a novel method of electrode modification based on AuNPs modified nitrocellulose membrane (NC membrane) was applied to detect bacterial proliferation through electrochemical impedance to accurately quantify antibiotics. The NC-AuNPs-Anti composite membrane was adopted for time-lapse effect of low concentration of amikacin sulfate on E. coli, and the change in AC impedance was analyzed by the equivalent model. t-SNE method was applied to visualize high-dimensional parameters and perform feature screening, and a machine learning model was adopted to accurately predict antibiotics. The experimental results show that this method can reach the antibiotic prediction accuracy of ±2.9E- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$03 ~\mu \text{L}$ </tex-math></inline-formula> /mL at 2, 3, and 4 hours after dosing, so as to provide a better quantitative analysis method for accurate antibiotic evaluation through the electrochemical impedance detection by bacteria proliferation.

A microfluidic device for accurate detection of hs-cTnI

This device is aimed at ensuring that the sample is uniformly and equivalently reacted with the antibody on the NC membrane in each test when the microfluidic liquid system is introduced to the chip. In this study, the developed microfluidic chip can avoid the presence of the sample and conjugate pads in the chip, while the precision of the chromatography system can be greatly improved using the same particles, NC membrane and antibody alongside the traditional strip. The results, taking the detection of cTnI as an example, revealed that the coefficient of variation (CV) is controlled within 4%, while the maximum record of the contrast chromatographic reagent strip can reach 15%. Additionally, the detection sensitivity can maintain the same order of magnitudes with that of the traditional chromatographic strip. With the results, the determination correlation of the developed microfluidic chip has been greatly improved. In addition, the CV of the chip in this study is greatly improved in comparison with that of the traditional strip. The biggest improvement lies in the mixing between the sample and the microspheres, indicating that this is a new approach to improve the CV of the traditional strip.

Chitosan-modified nitrocellulose membrane for paper-based point-of-care testing

Green/sustainable cellulose paper-based platforms at point-of-care testing have received much interest in biomedical fields at resource-limited settings. In such platforms, biomolecules would have to be immobilized onto paper substrate to achieve detection. Therefore, effective molecule immobilization is critical for the performance of paper-based testing, especially the detection sensitivity. Although various methods have been developed to improve the detection sensitivity, the immobilization capacity of biomolecules has not been considered yet. In this study, we developed a facile method for modifying paper materials by incorporating chitosan into NC membrane, which has positive effect on the pore size, porosity, and surface groups of NC membrane, hence, enhancing the immobilization capacity of biomolecules on paper substrate. We demonstrated the effectiveness of the above mentioned approach by using nucleic acid lateral flow assay (NALFAs) as a model paper-based platform; in comparison with the unmodified NALFAs, the results showed ten-fold increase in the detection sensitivity for HBV. We envision that this facile modification method will have a great potential for developing other highly sensitive paper-based detecting platforms.

A modified protein persulfidation detection method

As a gastransmitter, hydrogen sulfide (H2S) plays an important role in regulating plant growth and stress resistance. The proposed functional mechanism of H2S is persulfidation, a kind of posttranslational modification on free cysteine residues of proteins, which is also called S-sulfhydration previously. At present, biotin switch assay is an effective method for protein persulfidation level detection, while the protein sample need be precipitated and resuspended repeatedly according to the current protocol. Here, we reported a modified method which adapted from biotin switch assay and reduced the repetitive steps mentioned above. The total protein of plant or purified recombination protein from E. coli was directly loaded on the activated NC membrane. The free sulfhydryl of cysteine residues of protein on NC membrane could be blocked with MMTS reagent, while the persulfidation modified cysteine residues would be labeled by biotin-HPDP. After that, the persulfidation level of proteins was detected by immunoblotting with anti-biotin antibodies. This method was also applicable to the plant proteins, which were transferred to NC membrane after separated by native PAGE. This method reduces the repeated steps of precipitation and resuspension of protein samples, and by this it could reduce the loss and content error of protein. Besides, it is more sensitive and convenient than the previous biotin switch assay method.

Microstructural effects on permeability of Nitrocellulose membranes for biomedical applications

Nitrocellulose membrane (NC), as a paper-like matrix with microscale porous structures, has found widespread applications in biomedical fields due to its excellent biological features and physiochemical properties. In these biomedical applications, diffusion, convection, and binding reaction of biomolecules (e.g., acids and proteins) in NC through wicking flow is the fundamental physical process. However, the optimization of NC based biomedical devices has been limited by the lack of the understanding on the wicking flow behavior of NC membranes from the microstructural point of view. To address this, we experimentally and theoretically investigated the microstructural effects on the wicking flow behaviors (e.g., permeability, effective pore radius) of NC membrane and found that the wicking flow is highly dependent on the pore-morphology characterizing parameters (e.g., porosity and pore size). We further developed a theoretical model yielding a closed-form solution to predict the microstructure-permeability relation, which was validated by our experimental results. Our theoretical model would be a powerful tool for tailoring the wicking flow behavior of NC membranes through controlling the microstructural parameters, and thus for optimizing NC membrane-based biomedical devices from the view point of material design in the future.

A Novel Paper-plastic Microfluidic Hybrid Chip Integrated with a Lateral Flow Immunoassay for Dengue Nonstructural Protein 1 Antigen Detection

This study presents an easy paper-plastic hybrid microfluidic chip fabrication method that explored the use of oven baking a wax-printed pattern for microfluidic channel assembly combined with the use of a double-sided adhesive tape for layer binding. More specifically, the method includes printing of a wax pattern onto the CA film & oven baking of the pattern along with the backed NC membrane at 120°C for 2.5 minutes. The porous nature of the NC membrane allows the wax pattern to enter into its pores during the baking process and binds the backed NC membrane with the CA film. Attachment of the engraved PMMA layer was performed to increase the structural support. The engraved hole of the layer allows the conjugate pad with space for its integration into the system. Moreover, the antibodies required for the integration of the chip with the LFIA were selected by enzyme-linked immunosorbent assay (ELISA). A CA film, an NC membrane, and a PMMA sheet were used to develop a microfluidic chip that can be integrated with a sandwich format lateral flow immunoassay used to detect dengue non-structural 1 protein. The fabricated chip was able to successfully detect a concentration of dengue non-structural 1 protein of at least 84.66 ng/mL.

Development of an immunochromatographic strip test for the rapid detection of zearalenone in wheat from Jiangsu province, China

A colloidal gold (ICS) test was developed for rapid detection of zearalenone (ZEN) in wheat samples. The mAb against ZEN was prepared in our laboratory and labelled with colloidal gold as a probe for the ICS test. The conditions were optimized and 30 nm colloidal gold nanoparticles were chosen for optimal performance. Millipore 135 was chosen as the NC membrane for its level of sensitivity. The optimum amount of coated antigen ZEN-OVA and anti-ZEN mAb was 0.5 mg/mL and 8 μg/mL, respectively. The ICS test, which has a detection limit of 15 ng/mL for ZEN, could be completed in 5 min. Analysis of ZEN in 202 wheat samples over three consecutive years revealed that data obtained from the ICS test were in a good agreement with LC-MS/MS data. This result demonstrated that the ICS test could be used as a qualitative tool to screen on-site for ZEN.

A new immunochromatographic assay for on-site detection of porcine epidemic diarrhea virus based on monoclonal antibodies prepared by using cell surface fluorescence immunosorbent assay

BackgroundPorcine epidemic diarrhea virus (PEDV) is a highly effective pathogen that can cause death of new-born piglet, resulting in big economical loss in pig farming industry. For rapid detection of PEDV, a new immunochromatographic assay (ICA) based on monoclonal antibodies (mAbs) was developed in this study.ResultsThe mAbs were prepared by using PEDV positive hybridoma cells that were selected by using cell surface fluorescence immunosorbent assay (CSFIA). Fourteen mAbs against PEDV strain isolated from south of China were prepared. The optimal mAb 4A11 was coated on NC membrane as the capturing reagent and the mAb A11H7 was coupled to gold nanoparticles (AuNPs) as detection reagent for the new ICA. The new ICA was used to measure PEDV in phosphate buffer containing tween-20. Results indicated that the limit of detection (LOD) of the new ICA was 0.47 μg/mL (5.9 × 103 TCID50/mL) and the liner detection range of the ICA was 0.625–10 μg/mL (7.8 × 103–105 TCID50/mL). The specificity analysis results showed that this new ICA had no cross reaction in the presence of other porcine viruses. The ICA was also validated for the detection of PEDV in swine stool samples with little interference from swine stool. To compare its accuracy to other traditional detection methods, 27 swine stool samples from south of China were investigated with the new developed ICA, commercial strip and RT-PCR. Results showed that the new ICA was more comparable to RT-PCR than commercial test strip.ConclusionsA new ICA based on mAbs prepared by CSFIA was developed in this study. It was a sensitive, specific and rapid method that could be used for on-site detection of PEDV and therefore was useful for the diagnosis and prevention of PED.

A two-dimensional mathematical model for analyzing the effects of capture probe properties on the performance of lateral flow assays.

Lateral flow assays (LFAs) are promising candidates in biomedical diagnosis fields due to their rapid, low-cost, and portable features. However, improving their sensitivity remains challenging due to the unclear roles of capture probes with different distribution formats on the particle transfer and capturing in the test line. Therefore, we designed experiments and observed an asymmetrical U-shaped distribution of control probes throughout the NC membrane thickness. Based on this outcome, a two-dimensional mathematical model based on the Langmuir surface reaction kinetics was developed to investigate the effect of capture probe distributions on LFA performance. A two-dimensional model was qualitatively validated by comparing with the experimental results and the simulations of the reported one-dimensional model. Then, a higher detection signal was achieved by using the U-shaped distribution of capture probes throughout the NC membrane thickness instead of a uniform distribution. Furthermore, when the NC membrane thickness was less than 110 μm, the ratio of the detection signal in the visible region to the signal in the total section at the test line was above 13%. A thin NC membrane will produce a strong detection signal in the visible region at the test line. The developed model is capable of providing direct predictions in designing highly sensitive LFAs.

Development and application of a rapid semiquantitative immunochromatographic test strip to detect white spot syndrome virus

White spot syndrome virus (WSSV) is one of the most serious viral pathogens causing major economic losses to the shrimp farming industry worldwide. Rapid diagnostic test is critical for disease prevention and control. Previously we have developed a rapid immunochromatographic test strip for WSSV detection, but it is limited to the qualitative testing. In this study, a semiquantitative immunochromatographic test strip (SIT-strip) was developed for WSSV detection by observing the number of positive test lines to determine the viral load levels. To achieve semiquantitative analytical ability, three test lines were designed on NC membrane to form the test zone, on which different concentration of anti-WSSV monoclonal antibody (MAb) 4G9 in a decreasing sequence from test line (TL) I to TL-III was dispensed, instead of the traditional application of a single test line. The anti-WSSV MAb 2E6 served as colloidal gold conjugate and goat anti-mouse IgG antibody on control line was used to validate the test performance. The threshold concentrations for TL-I, -II and -III were determined to be 783 ng/ml, 3.13 μg/ml and 6.26 μg/ml of WSSV, respectively, and the visual detection limit of the SIT-strip was 783 ng/ml. The developed SIT-strip was used to detect WSSV at different time points post injection of Procambarus clarkia, the results indicated that one red band was present on TL-I at 12 h post infection (hpi) in the gills, two bands in muscle and three bands in gills and hemolymph were produced at 24 hpi although there was no death at that time, and thereafter three bands were visible in all tested tissues and dead individuals. The mortality was low from 36 to 48 hpi and increased rapidly during 48–72 hpi. Meanwhile, WSSV copy numbers were detected by real time qPCR for severity grading of infection. These results revealed that this SIT-strip could provide confirmation of viral presence and concentration levels prior to mortality, which was early enough to achieve the goal of monitoring for WSSV infection loads predictive of impending disease.

A novel colloidal gold labeled antigen for the detection of Deoxynivalenol using an immunochromatographic assay method

In this paper, an immunochromatographic assay card was developed for the detection of DON in feed and cereals using a novel colloidal gold labeling method. For the colloidal gold immunochromatographic rapid detection (GICD) card, a monoclonal antibody DON-mAb and a goat anti-chicken IgY were drawn on NC membrane as the test line (T line) and the control line (C line) respectively. A gold labeled DON-CBSA conjugate and a gold labeled chicken IgY were sprayed onto the conjugate pad. The GICD card has cut-off levels of 50ng/mL for DON, which is invulnerable to matrix interference, and applicable to a wide range of samples. The GICD detecting results of feed and grain samples were compared with the results of ELISA testing, which showed good consistency.