Gold Nanoparticle-based Immunochromatographic Assay Research Articles

Gold nanoparticle-based immunochromatographic assay for rapid detection of imazalil.

Imazalil (IMZ) is a commonly used fungicide for controlling fungus in agriculture, leaving residual IMZ in crops that could be hazardous to human health. In this work, we designed IMZ haptens for mice immunization and prepared sensitive monoclonal antibody (mAb) against IMZ. The subtype of anti-IMZ mAb is IgG2a. It possessed a half inhibition concentration (IC50) of 0.95 ng mL-1 and showed no cross-reactivity against other chemicals in ic-ELISA. Taking advantage of the mAb, we developed a gold nanoparticle-based immunochromatographic assay (GICA) for the rapid detection of IMZ in grapes and tomatoes. The assay gave a visual limit of detection (vLOD) of 25 ng g-1 and cut-off value of 500 ng g-1 in both samples. According to the calibration curves, the calculated LOD were 4.12 ng g-1 and 4.70 ng g-1 in grapes and tomatoes, respectively. The recovery rates of IMZ ranged from 84.7% to 104.4% with variation coefficients (CVs) of 5.7-11.8% in spiked samples, indicating a potent practicability of the GICA. The whole GICA process took 30 min. Therefore, the developed assay can be used for on-site detection and quantitation of IMZ in grape and tomato samples.

Gold nanoparticle-based immunochromatographic assay for the detection of fenhexamid in cucumber and grape samples

Gold nanoparticle-based immunochromatographic assay for the detection of fenhexamid in cucumber and grape samples

Broad-specificity monoclonal antibody against neonicotinoid insecticides via a multi-immunogen strategy and development of a highly sensitive GNP-based multi-residue immunoassay in ginseng and tomato

Neonicotinoid insecticides (NNIs) are extensively used across the agricultural products and foods. In order to meet the rapid detection requirements, a novel broad-specificity monoclonal antibody against NNIs was developed for the first time using a multi-immunogen strategy. The antibody’s high affinity and its ability to bind target molecules were verified by ic-ELISA. Furthermore, molecular docking was used to evaluate the pivotal forces affecting binding affinity and to determine binding sites. Subsequently, a highly sensitive gold nanoparticle-based immunochromatographic assay was established for the rapid detection of eight NNIs and the IC50 values were 0.03–1.61 ng/mL. The limits of detection for ginseng and tomato ranged from 0.76 to 30.19 μg/kg and 0.87 to 31.57 μg/kg, respectively. The spiked recovery ranged from 72.04% to 120.74%, and the coefficient of variation were less than 9.0%. This study provides a new direction for the development of multiple NNIs residue immunoassays.

Gold nanoparticle-based immunochromatographic assay for the rapid detection of the SARS-CoV-2 Omicron variant

At present, the prevalent Omicron mutant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has the characteristics of high infectivity and strong concealment, leading to more asymptomatic infections.

Rapid and sensitive detection of tert-butylhydroquinone in soybean oil using a gold-based paper sensor.

tert-Butylhydroquinone (TBHQ) residues in foods pose a threat to human health. Therefore, it is necessary to develop a rapid method for TBHQ detection. In this study, a sensitive monoclonal antibody 5C3 (IgG2a subclass) against TBHQ was produced. It possessed a half maximal inhibitory concentration of 7.43 ng mL-1. A gold nanoparticle-based immunochromatographic assay (ICA) was established for the rapid and sensitive screening of TBHQ in soybean oil. Qualitative analysis results were obtained within 10 min and observed with the naked eye. The visual limit of detection (LOD) was 50 ng g-1 and the cut-off value was 1000 ng g-1. A hand-held strip reader was used for quantitative analysis, in which the calculated LOD was defined as 18.68 ng g-1. The average recoveries of TBHQ ranged from 89.55% ± 2.70% to 100.66% ± 3.02% for soybean oil, with a coefficient of variation of 2.89%-7.05%. Therefore, our developed ICA is a useful tool for the rapid and on-site detection of TBHQ in real food samples.

Avoiding the self-nucleation interference: a pH-regulated gold in situ growth strategy to enable ultrasensitive immunochromatographic diagnostics.

Background: Gold nanoparticle-based immunochromatographic assay (AuNP-ICA) has insufficient sensitivity due to its inherent colorimetric signal intensity and low capture efficiency of AuNPs. The metal in situ growth is a common strategy to enhance the sensitivity of AuNP-ICA due to its superior signal amplification potential and simple operation. However, the detection distortion caused by metal self-nucleation during the growth process can seriously affect the accuracy and reproducibility of the strips.Methods: We present a pH-regulated gold in situ growth (GISG) strategy to amplify the colorimetric signal and demonstrate its application in improving the performance of traditional AuNP-ICA. The controllable growth signal amplification is achieved by lowering the pH of the growth solution to weaken the reducibility of hydroxylamine (HA), thus urging the crystallization and growth of Au3+ on the AuNP surface instead of free reduction and self-nucleation. In addition, the mechanism of pH regulation on HA reducibility is elucidated by introducing an electron-donating or electron-withdrawing group to affect the electron density of hydroxyl group.Results: The proposed GISG strategy shows improved sensitivity, low background, robust operation, and good reproducibility. The LOD values of the designed GISG-amplified AuNP-ICA are as low as 0.0198 ng mL-1 for hepatitis B surface antigen and 0.0125 ng mL-1 for HIV-1 capsid p24 antigen, which are lower by about 500- and 70-fold, respectively, than those of the unamplified AuNP-ICA.Conclusions: This method is extended to enable ultrasensitive and rapid diagnosis of viral infections, and has potential as a general signal amplification platform to redefine immunochromatographic diagnostics.

Gold nanoparticle-based immunochromatographic assay for detection Pseudomonas aeruginosa in water and food samples

Pseudomonas aeruginosa (P. aeruginosa) is the common infection-causing bacterial pathogen. Conventional methods for the detection of P. aeruginosa are time-consuming, and therefore, a more rapid analytical method is required. Here, monoclonal antibodies (Mabs) against P. aeruginosa (CICC 10419) were prepared and based on paired Mabs, an immunochromatographic assay (ICA) was developed. The ICA strip showed a limit of detection of 2.41 × 104 CFU/mL and the linear range of detection was 3.13 × 104-1.0 × 106 CFU/mL. No cross-reactivity was observed when other common Gram-negative and Gram-positive bacteria were used. The analytical performance of the ICA strip indicated that the developed ICA had good specificity and stability. Moreover, the feasibility of the ICA strip was verified by detecting P. aeruginosa (CICC 10419) in spiked water and food samples. The ICA strip could detect samples contaminated with a low-level of P. aeruginosa (CICC 10419) after 8 h enrichment.

A gold nanoparticle-based immunochromatographic assay for simultaneous detection of multiplex sildenafil adulterants in health food by only one antibody

In the last few years, sildenafil and its analogues have emerged as an illegal ingredient in health food and products, causing illness and death. To address this problem, herein, a gold nanoparticle-based immunochromatographic assay for simultaneous detection sildenafil and its analogues was developed by using just one monoclonal antibody. This method can realize qualitative and quantitative analysis of sildenafil and its analogues with a detection range (IC20-IC80) of 0.12-28.05ngmL-1, the IC50 was 0.31-8.45ngmL-1 and the cut-off value was 5.0-80.0ngmL-1. Meanwhile, this method could also accomplish semi-quantitative analysis of vardenafil with a cut-off value of 0.625ngmL-1. The detection can be finished in 6min and showed no cross-reactivity with avanafil and tadalafil. The recoveries of spiked samples ranged from 70.5 to 118.9% with a coefficient variation less than 15%, which confirmed the assay was sensitive, accurate and adapted to the rapid determination of sildenafil and its analogues.

Immunochromatographic assay for the detection of kwakhurin and its application for the identification of Pueraria candollei var. mirifica (Airy Shaw & Suvat.) Niyomdham

The plant Pueraria candollei var. mirifica (Airy Shaw & Suvat.) Niyomdham (PM), known by its common Thai name as white Kwao Krua, is sometimes misidentified because it presents similar botanical characteristics to those of Butea superba (red Kwao Krua). The phytochemicals in PM are phytoestrogens in the class of isoflavonoids, but Butea superba contains flavonoids that exhibit androgenic and antiestrogen effects. This research aims to develop a simple analytical method for identification and to differentiate PM from red Kwao Krua and other Pueraria species. A gold nanoparticle-based immunochromatographic assay (ICA) was developed for the detection of kwakhurin (Kwa), a unique compound found in PM. The parameters, including sensitivity, accuracy, precision, and specificity, were validated. All samples were analyzed using ICA and high-performance liquid chromatography with UV detector (HPLC-UV). The results of the two methods were compared for consistency checking. The cutoff limit of Kwa detection was 160 ng/mL, which was lower than in the HPLC-UV method. The repeatability and reproducibility of the ICA preparation and assembly showed high precision. The cross-reactivity to related isoflavonoids was less than 0.32%, which implied high specificity of the ICA for Kwa. Moreover, false-positive and false-negative results from other plant extracts were not observed. The developed ICA is applicable for distinguishing PM from red Kwao Krua and other Pueraria species. This simple analytical method can be applied for the identification of raw PM materials in the industrial and agricultural sectors.

Rapid and Sensitive Immunochromatographic Method-Based Monoclonal Antibody for the Quantitative Detection of Metalaxyl in Tobacco.

In this study, we prepared a monoclonal antibody (mAb) against metalaxyl (Met) with a half-maximum inhibitory concentration (IC50) of 0.54 ng/mL based on a new hapten, and a gold nanoparticle-based immunochromatographic assay (GICA) was developed for the rapid detection of Met residues in tobacco. Under optimal conditions, even with the naked eye, one can see the semiquantitative analysis results. The naked eye detection limit of Met in tobacco is 25 μg/kg, and the detection threshold is 100 μg/kg. In addition, the cross-reactivity test shows that the mAb has good specificity for Met, and the GICA results have a good correlation with the indirect competitive enzyme-linked immunosorbent assay and liquid chromatography with tandem mass spectrometry test results, which show that the method is feasible and reliable and are more convenient and quicker than the methods using instrumentation for detection. Therefore, GICA may provide a useful tool for the rapid screening and detection of Met residues in tobacco.

Semi-quantification of HIV-1 protease inhibitor concentrations in clinical samples of HIV-infected patients using a gold nanoparticle-based immunochromatographic assay

Individual drug concentration data can be a valuable tool for the clinical management of antiretroviral therapy (ART) for the treatment of HIV infection. High performance liquid chromatography (HPLC) based assays are currently the gold standard for drug measurement but its high cost and requirement of technical expertise limits its widespread use. Simpler user-friendly and inexpensive detection assays are needed. A novel immunochromatographic (IC) strip test to detect HIV-1 protease inhibitors (PIs) was fabricated by combining the proteolysis activity of HIV-protease (PR) and an immunochromatographic reaction. The PIs-IC strip cut-off to detect lopinavir (LPV) concentrations was set at 1,000 ng mL−1. We evaluated this novel PIs-IC strip for the semi-quantification of HIV PIs in plasma samples collected from healthy subjects and HIV-infected patients receiving antiretroviral treatment with and without LPV. LPV plasma drug levels were quantified by HPLC and evaluated (blinded to the HPLC results) using the PIs-IC strip. Results of plasma samples tested using the PIs-IC strip were available within 5 min. Using the PIs-IC strip test the accuracy, specificity and sensitivity were 97.8%, 97.1%, and 100%, respectively, compare to the gold-standard assay, to detect LPV in human plasma samples. This novel PIs-IC strip test could be used as a simple tool for the rapid monitoring of PIs levels in HIV-infected patients, although further clinical evaluation is needed.

Sulfonated polystyrene magnetic nanobeads coupled with immunochromatographic strip for clenbuterol determination in pork muscle

A magnetic solid-phase extraction method (MSPE) was developed to pre-concentrate and cleanup clenbuterol (CLE) from pork muscle. Novel sulfonated polystyrene magnetic nanobeads (spMNBs) were synthesized via a one-pot emulsion copolymerization method by using divinylbenzene, styrene, and sodium styrene sulfonate in the presence of oleic acid-modified and 10-undecylenic acid-modified magnetic ferrofluid. The resulting spMNBs exhibited high adsorption efficiency for CLE and for 10 other common beta-adrenergic agonists, namely, brombuterol, ractopamine, tulobuterol, bambuterol, cimbuterol, mabuterol, clorprenaline, penbutolol, salbutamol, and cimaterol. The adsorption behavior of the spMNBs for CLE was described by the Langmuir equation with a maximum adsorption capacity of 0.41 mg/g. Under the optimized parameters, the extraction of CLE from 0.5g of pork muscle required 25mg of the spMNBs at a shortened adsorption time (0.5min). The proposed MSPE was coupled with colloidal gold nanoparticle-based immunochromatographic assay (MSPE–AuNPIA) for the quantitative detection of CLE residue in pork muscle. The limit of detection and limit of quantification for the pork muscle were 0.10 and 0.24ng/g, respectively. The intra-day and inter-day assay recoveries at three CLE spiked concentrations ranged from 92.5% to 98.1%, with relative standard deviations ranging from 3.2% to 13.0%. The results of MSPE–AuNPIA were confirmed by liquid chromatography-tandem mass spectrometry (LC–MS/MS). The CLE values obtained with MSPE–AuNPIA agreed with those obtained with LC–MS/MS.

A gold nanoparticle-based immunochromatographic assay: The influence of nanoparticulate size

Four different sized gold nanoparticles (14 nm, 16 nm, 35 nm and 38 nm) were prepared to conjugate an antibody for a gold nanoparticle-based immunochromatographic assay which has many applications in both basic research and clinical diagnosis. This study focuses on the conjugation efficiency of the antibody with different sized gold nanoparticles. The effect of factors such as pH value and concentration of antibody has been quantificationally discussed using spectra methods after adding 1 wt% NaCl which induced gold nanoparticle aggregation. It was found that different sized gold nanoparticles had different conjugation efficiencies under different pH values and concentrations of antibody. Among the four sized gold nanoparticles, the 16 nm gold nanoparticles have the minimum requirement for antibody concentrations to avoid aggregation comparing to other sized gold nanoparticles but are less sensitive for detecting the real sample compared to the 38 nm gold nanoparticles. Consequently, different sized gold nanoparticles should be labeled with antibody under optimal pH value and optimal concentrations of antibody. It will be helpful for the application of antibody-labeled gold nanoparticles in the fields of clinic diagnosis, environmental analysis and so on in future.

Gold nanoparticle-based immunochromatographic assay for the detection of 7-aminoclonazepam in urine

An analytical system of immunochromatographic assay based on gold nanoparticles was developed for the detection of 7-aminoclonazepam (7-ACLZ) in human urine. The qualitative assay was based on the competitive immunoassay using anti-7-ACLZ polyclonal antibody (PcAb) and a detector reagent that contains colloidal gold particles coated with anti-7-ACLZ PcAb. Nitrocellulose membrane was separately immobilised with goat anti-rabbit IgG (control line) and 7-ACLZ-OVA conjugate (test line). The sensitivity of the strip was tested for detecting 7-ACLZ spiked in urine and each specimen was independently measured by liquid chromatography tandem mass spectrometry. Good correlation was showed by the recovery results. The limit of detection for the strip test in urine was 100 ng mL−1. The assay can be applied to the rapid detection of 7-ACLZ with the short testing time.

Gold nanoparticle-based immunochromatographic assay for the detection of Staphylococcus aureus

An analytical system of immunochromatographic assay based on gold nanoparticles was developed for the detection of Staphylococcus aureus. Staphylococcal protein A, a cell wall protein of S. aureus, has the ability to interact with several host components, possibly indicating a role as a virulence factor in S. aureus infections. The assay was constructed in the form of sandwich by using anti-protein A IgG with two distinct specificities. One anti-protein A IgG was immobilized in a defined detection zone on a porous nitrocellulose membrane, while the other anti-protein A IgG was conjugated with gold nanoparticles. The sample flows along the porous membrane by capillary action past the anti-protein A IgG in the detection zone, binding the particles that to which surface protein A was already bound to their surface, yielding a red color. The rapid observation of results directly by the naked eye ensures the convenience of performing bioassays on field. As the results, the sensitivity in the immunochromatographic test of 306 S. aureus strains were 100% and the specificity of 44 non-S. aureus strains were 96.0 to 100%. Twelve processed food samples inoculated artificially with 0.9, 1.2, 2.4, and 6 CFU/g of S. aureus and all yielded positive results in the immunochromatographic test. As compared to the conventional culture methods which take 5 to 6 days to complete, the immunochromatographic test can detect low numbers of S. aureus in processed foods with a total analytical time of only 25 h.