Colloidal Gold Immunochromatography Research Articles

An ultrasensitive strip sensor for rapid detection of African swine fever virus

African swine fever (ASF) is a highly contagious disease caused by the African swine fever virus (ASFV) infecting pigs, which has caused huge economic losses in countries around the world. Currently, there is no effective vaccine, and the prevention and control of ASF is mainly through rapid detection, so it is particularly important to carry identify and develop rapid detection methods for ASFV. In this study, recombinant plasmid PET-28a(+)-p30 was constructed, and the recombinant protein was obtained by inducing expression and Ni+ resin affinity column purification. Mice were immunized with recombinant p30 protein, and after three immunizations, ten strains of hybridoma cells that stably secreted monoclonal antibodies (mAbs) against p30 protein were obtained by cell fusion and subcloning. A colloidal gold immunochromatography assay (GICA) based on double antibody sandwich technology was established to screen the paired antibodies, and the trapping and detecting antibodies were mAb-11F11 and mAb-7A8, respectively, with a detection limit of 1 ng/mL, which laid an important material foundation for the early detection of ASF in the future.

Development of a colloidal gold immunochromatographic strip for the simultaneous detection of porcine epidemic diarrhea virus and transmissible gastroenteritis virus.

In recent years, porcine diarrhea-associated viruses have caused significant economic losses globally. These viruses present similar clinical symptoms, such as watery diarrhea, dehydration, and vomiting. Co-infections with porcine epidemic diarrhea virus (PEDV) and transmissible gastroenteritis virus (TGEV) are common. For the rapid and on-site preliminary diagnosis on the pig farms, this study aimed to develop a colloidal gold immunochromatography assay (GICA) strip for the detection of PEDV and TGEV simultaneously. The GICA kit showed that there was no cross-reactivity with the other five common porcine viruses. With visual observation, the lower limits were approximately 104 TCID50/mL and 104 TCID50/mL for PEDV and TGEV, respectively. The GICA strip could be stored at 4°C or 25°C for 12 months without affecting its efficacy. To validate the GICA strip, 121 clinical samples were tested. The positive rates of PEDV and TGEV were 42.9 and 9.9%, respectively, and the co-infection rate of the two viruses was 5.8% based on the duplex GICA strip. Thus, the established GICA strip is a rapid, specific, and stable tool for on-site preliminary diagnosis of PEDV- and TGEV-associated diarrhea.

Development of Detection Antibody Targeting the Linear Epitope in SARS-CoV-2 Nucleocapsid Protein with Ultra-High Sensitivity.

The COVID-19 pandemic caused by SARS-CoV-2 highlighted the importance of reliable detection methods for disease control and surveillance. Optimizing detection antibodies by rational screening antigens would improve the sensitivity and specificity of antibody-based detection methods such as colloidal gold immunochromatography. In this study, we screened three peptide antigens with conserved sequences in the N protein of SARS-CoV-2 using bioinformatical and structural biological analyses. Antibodies that specifically recognize these peptides were prepared. The epitope of the peptide that had the highest binding affinity with its antibody was located on the surface of the N protein, which was favorable for antibody binding. Using the optimal antibody that can recognize this epitope, we developed colloidal gold immunochromatography, which can detect the N protein at 10 pg/mL. Importantly, this antibody could effectively recognize both the natural peptide antigen and mutated peptide antigen in the N protein, showing the feasibility of being applied in the large-scale population testing of SARS-CoV-2. Our study provides a platform with reference significance for the rational screening of detection antibodies with high sensitivity, specificity, and reliability for SARS-CoV-2 and other pathogens.

Rapid detection of the freshness of grass carp (Ctenopharygodon idella) fillets by colloidal gold immunochromatography assay

Consumers are greatly concerned about fish freshness. Therefore, this study was aimed to provide a colloidal gold immunochromatography assay (GICA) system for rapid detection of fish freshness. A suitable fish protein was chosen as an antigen for GICA; and the properties and effectiveness of the GICA system were investigated. Results showed that parvalbumin (PV) was suitable as a fish freshness indicator, proven by hierarchical cluster analysis and chosen as a GICA antigen. The GICA system revealed high specificity in the 27–212 μg/L detection range. The correlation coefficient R2 towards enzyme-linked immunosorbent assay reflected high reliability as 0.998. The GICA system was stable within 12 weeks at room temperature. The fitness for indicating freshness by GICA ranged from 87.27% to 111.72%. In short, the GICA system with PV as an antigen could be used as a simple, rapid, and accurate technique for the freshness detection of grass carp fillets.

Progress in Procalcitonin Detection Based on Immunoassay.

Procalcitonin (PCT) serves as a crucial biomarker utilized in diverse clinical contexts, including sepsis diagnosis and emergency departments. Its applications extend to identifying pathogens, assessing infection severity, guiding drug administration, and implementing theranostic strategies. However, current clinical deployed methods cannot meet the needs for accurate or real-time quantitative monitoring of PCT. This review aims to introduce these emerging PCT immunoassay technologies, focusing on analyzing their advantages in improving detection performances, such as easy operation and high precision. The fundamental principles and characteristics of state-of-the-art methods are first introduced, including chemiluminescence, immunofluorescence, latex-enhanced turbidity, enzyme-linked immunosorbent, colloidal gold immunochromatography, and radioimmunoassay. Then, improved methods using new materials and new technologies are briefly described, for instance, the combination with responsive nanomaterials, Raman spectroscopy, and digital microfluidics. Finally, the detection performance parameters of these methods and the clinical importance of PCT detection are also discussed.

Application of Octenidine into Nasal Vestibules Does Not Influence SARS-CoV-2 Detection via PCR or Antigen Test Methods.

The targeted or universal decolonization of patients through octenidine for nasal treatment and antiseptic body wash for 3 to 5 days prior elective surgery has been implemented in several surgical disciplines in order to significantly reduce surgical site infections (SSIs) caused by Staphylococcus aureus carriage. However, as most healthcare facilities also screen patients on admission for pilot infection, it is imperative that a prophylactic nasal decolonization procedure not yield a false negative SARS-CoV-2 status in otherwise positive patients. We assessed the effect of a commercially available octenidine-containing nasal gel on two different screening methods-antigen (Ag) detection based on colloidal gold immunochromatography and RT-PCR-in a prospective-type accuracy pilot study in asymptomatic SARS-CoV-2-positive inpatients. All patients still showed a positive test result after using the octenidine-containing nasal gel for about 3 days; therefore, its application did not influence SARS-CoV-2 screening, which is of high clinical relevance. Of note is that Ag detection was less sensitive, regardless of the presence of octenidine. From an infection prevention perspective, these results favor octenidine-based decolonization strategies, even during seasonal SARS-CoV-2 periods. As only asymptomatic patients are considered for elective interventions, screening programs based on RT-PCR technology should be preferred.

COMPARATIVE STUDY TO DETECT ANTIBIOTIC RESIDUES IN PROCESSED AND RAW MILK IN LAHORE

Antibiotics help animals and human beings live longer and healthier lives. But if antibiotics are used carelessly or inappropriately, or if the required withdrawal period is not understood, it's possible that treated animals' products will include unintended antibiotic residues. Many of these life-saving drugs are losing their efficacy as formerly vulnerable microorganisms (bacteria, viruses, fungi and microscopic-parasites) develop resistance. This phenomenon is called “antimicrobial resistance” or AMR. Antimicrobial usage (AMU) is a significant risk factor for antimicrobial resistance (AMR) development. The aim of this study was to investigate the presence of β-lactam and tetracyclines antibiotic residues in raw (cow and buffalo) milk and processed (UHT and pasteurized) milk in District Lahore. For that purpose, a total of 200 milk samples, containing 100 raw milk samples and 100 processed milk samples were collected from 5 zones of Lahore. The samples were processed using Milk Antibiotic Residues Rapid Test (Bioeasy) for β-lactams and tetracyclines in the milk kit method which is based upon colloidal gold immunochromatography technology also known as lateral flow dipstick immunoassay. Among total of 200 milk samples, the results showed as 6.5% of milk samples were positive for only beta-lactams, 1.5% milk samples were positive for only tetracyclines, 9.5% milk samples exhibited dual positivity for both beta-lactams and tetracyclines, 8.5% milk samples demonstrated weak positive results for both antibiotics, and 74% milk samples were negative for beta-lactams and tetracyclines both. The calculated p-value (0.0004998) indicates a significant difference between the observed samples in terms of antibiotic residue presence by Fisher's exact test. These residues were more in the raw milk as compared to the processed milk. Regulatory authorities should ensure proper withdrawal period before milking the animals and definite supervisions are necessary on application of these drugs as this is the serious healthcare concern in Lahore.

Development of Colloidal Gold Test Strips for the Detection of Oxamyl Residues in Tobacco.

In this study, monoclonal antibodies against oxamyl were prepared, and colloidal gold immunochromatography was used to design a rapid test strip product for the detection of oxamyl in tobacco with high specificity, accuracy and stability without cross-reactivity to commonly used tobacco fungicides based on the optimization of conditions such as pH value of diluent, diluent dosage, concentration of antibody marker, type of confining solution and complex solution. 5 The results of five samples of post-harvest ready-to-bake tobacco and first-harvest tobacco were consistent with the gas chromatographic method, which proved the reliability of the test strips. The limits of detection for the post-harvest and first-harvest tobacco samples were 0.1 mg/kg, and the test strips developed in this study are suitable for mass testing in tobacco laboratories with good application prospects because of their short detection time, simple pre-treatment and detection methods.

Establishment of a Colloidal Gold Immunochromatographic Method for the Detection of Cypermethrin in Tobacco.

In this study, the establishment of a colloidal gold immunochromatographic method for the detection of cypermethrin in tobacco was achieved by using colloidal gold immunochromatography: strong specificity and high sensitivity of cypermethrin semi-antigens and encapsulants were prepared during the study. The best colloidal gold solution was prepared by spectrophotometer and transmission electron microscope screening; the preparation process of gold-labeled antibodies was optimized, and finally the product of colloidal gold rapid detection test strips for cypermethrin was developed. The results of technical parameters and detection indexes showed that the detection limit of cypermethrin in tobacco was 1 mg/kg, and there was no cross-reaction with bifenthrin, cypermethrin, cyfluthrin and phenothrin, and the detection results of 30 tobacco samples were consistent with those of gas chromatography.

Seroprevalence of SARS-CoV-2 in Niger State: Pilot Cross-Sectional Study.

The COVID-19 pandemic caused by SARS-CoV-2 is causing ongoing human and socioeconomic losses. To know how far the virus has spread in Niger State, Nigeria, a pilot study was carried out to determine the SARS-CoV-2 seroprevalence, patterns, dynamics, and risk factors in the state. A cross-sectional study design and clustered, stratified random sampling strategy were used to select 185 test participants across the state. SARS-CoV-2 IgG and IgM rapid test kits (colloidal gold immunochromatography lateral flow system) were used to determine the presence or absence of antibodies to the virus in the blood of sampled participants across Niger State from June 26 to 30, 2020. The test kits were validated using the blood samples of some of the Nigeria Center for Disease Control-confirmed positive and negative COVID-19 cases in the state. SARS-CoV-2 IgG and IgM test results were entered into the Epi Info questionnaire administered simultaneously with each test. Epi Info was then used to calculate the arithmetic mean and percentage, odds ratio, χ2 statistic, and regression at a 95% CI of the data generated. The seroprevalence of SARS-CoV-2 in Niger State was found to be 25.4% (47/185) and 2.2% (4/185) for the positive IgG and IgM results, respectively. Seroprevalence among age groups, genders, and occupations varied widely. The COVID-19 asymptomatic rate in the state was found to be 46.8% (22/47). The risk analyses showed that the chances of infection are almost the same for both urban and rural dwellers in the state. However, health care workers, those who experienced flulike symptoms, and those who had contact with a person who traveled out of Nigeria in the last 6 months (February to June 2020) were at double the risk of being infected with the virus. More than half (101/185, 54.6%) of the participants in this study did not practice social distancing at any time since the pandemic started. Participants' knowledge, attitudes, and practices regarding COVID-19 are also discussed. The observed Niger State SARS-CoV-2 seroprevalence and infection patterns meansuggest that the virus has widely spread, far more SARS-CoV-2 infections have occurred than the reported cases, and there is a high asymptomatic COVID-19 rate across the state.

Generating Monoclonal Antibodies against Buprofezin and Developing Immunoassays for Its Residue Detection in Tea Samples.

The synthesis of a hapten and antigen for the preparation of a monoclonal antibody (mAb) for buprofezin is described. The recognition mechanism of hapten and buprofezin by monoclonal antibodies (mAb-19F2) is described. The effectiveness of the mAb-19F2 immunoassay technique was assessed, and the effective detection of buprofezin in tea samples was achieved through the establishment of indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and colloidal gold immunochromatography assay (GICA). The mAb-19F2 subtype was IgG1, with an IC50 of 1.8 ng/mL and a linear range (IC20-IC80) of 0.6-5.4 μg/L, and had a cross-reaction rate of less than 0.18% with 29 other pesticides (neonicotinoids and insect growth regulators). The study identified π-π stacking interactions between hapten and TYR-61 at the mAb-19F2 site and alkyl/phosphate interactions with TRP-105 and ARG-103. The ic-ELISA had an IC50 of 12.9 ng/mL in green tea and 5.65 ng/mL in black tea, with a recovery rate of 92.4%-101.0% and RSD of 2.1%-4.8%. The GICA had a limit of detection (LOD) was 500 ng/mL, with the complete disappearance of the test lines visible to the naked eye. The limit of quantitation (LOQ, IC20) was determined to be 16.8 ng/mL. Additionally, the developed GICA showed no cross-reactivity with neonicotinoid pesticides. The recovery rate of tea spiked recovered samples was 83.6%-92.2%, with an RSD of 5.3%-12.6%, and the results were consistent with the LC/MS method. This study is important for the real-time detection of buprofezin residues to ensure food safety and human health.

Establishment of colloidal gold immunochromatography strip for rapid detection of Karen mikimotoi and its application.

In China, harmful algal blooms (HABs) are one of the most prominent ecological disasters in the coastal areas. Among the harmful algae species that cause HABs, Karen mikimotoi is a kind of algae that appear frequently. It can secrete hemolytic toxins and fish toxins such as glycolipids and unsaturated fatty, posing a significant threat to marine life. In order to establish a fast and effective detection technology for Karen mikimotoi that can be promoted and applied on site, we have developed a test strip which is based on monoclonal antibody technology and the colloidal gold immune-chromatography assay (GICA). The experimental results show that this test strip can detect different growth stages including growth, and stable and recession period of Karen mikimotoi. The detection results can be displayed within 3-15min. It had high sensitivity and specificity, with a detection limit of 754 cells/mL. A colorimetric card was made to further determine the concentration of algae detected. What is more, we had developed a method that can be used for on-site enrichment of algae cells using a syringe to detect lower concentrations of Karen mikimotoi, with a minimum detection concentration of 100 cells/mL. Also the test strip was used for on-site testing along the coast of China. This test strip not only serves as a warning for the outbreak of red tide, but also provides a new approach for the development of rapid detection technology for red tide algae.

B-066 Evaluation on Effectiveness of Colloidal Gold Immunochromatography Assay for Rapid Detection of Carbapenemase-producing Enterobacteriaceae

Abstract Background The identification, treatment, and control of carbapenem-resistant Enterobacteriaceae (CRE) infections are a major challenge for health care institutions and diagnostic laboratories worldwide. A novel Carbapenemase-producing Bacteria Test Kit (Lateral Flow Assay) from Dynamiker Biotechnology (Tianjin) Co., Ltd. is a qualitative test that was easy to operate and can be widely accepted by clinical and primary medical. Results can be read in just 15 minutes using colloidal gold immunochromatography, which can detect double and multiple carbapenemase types (Fig. 1). We analyzed the effectiveness of Dynamiker carbapenemase-producing bacteria test kit for rapid detection of CRE carbapenemase. Methods A total of 120 strains of Enterobacterales in blood culture were collected, including 80 strains of CRE and 40 strains of CSE (carbapenem-susceptibility Enterobacteriaceae). PCR was used to detect KPC, NDM, IMP, VIM and OXA-48 genes as gold standard. Dynamiker carbapenemase-producing bacteria test kit was used to detect the carbapenemase produced by CRE, which was conducted by the performance evaluation combined with PCR results. Results The 80 strains of CRE expressing carbapenemase genes were all positive for the detection of carbapenemasstre by Dynamiker carbapenemase-producing bacteria test kit, which includes 39 strains producing KPC, 26 strains producing NDM, 8 strains producing IMP, 5 strains producing VIM and 2 strains producing OXA-48 enzymes; the 40 strains of CSE were negative and no carbapenemase were detected. Compared with the PCR results, the sensitivity and specificity of the four enzymes by Dynamiker carbapenemase-producing bacteria test kit were both 100% (Fig. 2). Conclusion Dynamiker carbapenemase-producing bacteria test kit can be applied as a simple, rapid, sensitive and specific diagnostic method for the detection of different CRE carbapenemase types, which is of great value for the accurate use of clinical anti-infective therapy.Fig. 1.Operating procedures of colloidal gold immunochromatography.Fig. 2.Results of Dynamiker carbapenemase-producing bacteria test kit C: Control, K: KPC, N: NMD, I: IMP, V: VIM, O: OXA-48.

Epidemiological characteristics of New Delhi Metallo-β-Lactamase-producing Enterobacteriaceae in the Fourth hospital of Hebei Medical University

The epidemiological characteristics of New Delhi Metallo-β-Lactamase-Producing (NDM) Enterobacteriaceae were analyzed to provide theoretical support for clarifying the distribution characteristics of carbapenem-resistant Enterobacteriaceae (CRE) in the hospital environment and early identification of susceptible patients. From January 2017 to December 2021,42 strains of NDM-producing Enterobacteriaceae were gathered from the Fourth Hospital of Hebei Medical University, primarily Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae. The micro broth dilution method combined with the Kirby-Bauer method was used to determine the minimal inhibitory concentrations (MICs) of antibiotics. The carbapenem phenotype was detected by the modified carbapenem inactivation method (mCIM) and EDTA carbapenem inactivation method (eCIM). Carbapenem genotypes were detected by colloidal gold immunochromatography and real-time fluorescence PCR. The results of antimicrobial susceptibility testing showed that all NDM-producing Enterobacteriaceae were multiple antibiotic resistant, but the sensitivity rate to amikacin was high. Invasive surgery prior to culture, the use of excessive amounts of different antibiotics, the use of glucocorticoids, and ICU hospitalization were clinical characteristics of NDM-producing Enterobacteriaceae infection. Molecular typing of NDM-producing Escherichia coli and Klebsiella pneumoniae was carried out by Multilocus Sequence Typing (MLST), and the phylogenetic trees were constructed. Eight sequence types (STs) and two NDM variants were detected in 11 strains of Klebsiella pneumoniae, primarily ST17, and NDM-1. A total of 8 STs and 4 NDM variants were detected in 16 strains of Escherichia coli, mainly ST410, ST167, and NDM-5. For high-risk patients who have CRE infection, CRE screening should be done as soon as feasible to adopt prompt and efficient intervention measures to prevent outbreaks in the hospital.

Determining half-life of SARS-CoV-2 antigen in respiratory secretion

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is primarily transmitted from person to person through respiratory droplets and aerosols. It is also possible for the virus to be transmitted indirectly through environmental contamination. The likelihood of environmental transmission depends on several factors, including the survival time of the virus in respiratory secretions. However, the stability of SARS-CoV-2 in respiratory secretions has not been investigated. In this study, we compared the half-life of the SARS-CoV-2 antigen in respiratory secretion under different conditions. We applied respiratory secretion (5 µL) to glass slides, air-dried the slides for 1 h, and kept them at 24 °C or 4 °C for 10 days. Respiratory secretions were also placed in test tubes (sealed to preserve moisture) and in normal saline for 10 days. The concentration of SARS-CoV-2 antigen in all samples was simultaneously measured using colloidal gold immunochromatography, and the half-life of the antigen was calculated. The half-life of the antigen in the wet (sealed tube) and saline samples at room temperature was 5.0 and 2.92 days, respectively. The half-life of the antigen in the air-dried sample at room temperature and at 4 °C was 2.93 and 11.4 days, respectively. The half-life was longer in respiratory secretions than that in normal saline. The half-life was also longer in respiratory secretions, at a lower temperature, and under wet conditions. Therefore, environmental transmission can also play a significant role in the spread of the virus. Robust prevention and control strategies could be developed based on the half-life of the antigen in respiratory secretions.

Development of colloidal gold immunochromatography and reverse transcription loop-mediated isothermal amplification assays to detect lychnis mottle virus.

Lychnis mottle virus (LycMoV; genus Unassigned, family Secoviridae) infection of Angelica sinensis produces mottle and mosaic symptoms, damaging the host. Early detection of relevant pathogens is the most critical step in preventing the potential transmission of infectious disease. Polyclonal antibodies (pAbs) with high potency and high specificity were prepared using the recombinant LycMoV capsid protein as an antigen. Here, we developed and optimized a rapid colloidal gold immunochromatography assay (GICA) detection system for LycMoV using this antibody. Under optimum conditions, GICA specifically detected (up to 10,000-fold) positive LycMoV samples. A real-time reverse transcription loop-mediated isothermal amplification (RT-LAMP) system was also established by selecting the primers with high sensitivity and specificity to LycMoV. The RT-LAMP detection threshold was 1.42 fg/μl (291 copies/μl). A GICA-RT-LAMP assay system was further established and optimized. The minimum GICA detection line was calculated at 1.52x10-2 ng/μl. Although GICA did not detect positive samples after capturing 2.53x10-3 ng/μl of virus, GICA-LAMP and GICA-RT-PCR did, whose sensitivity was comparatively greater than six-fold. This is the first report showing that GICA-RT-LAMP is a cost effective approach for use in detecting LycMoV without extracting nucleic acids. These sensitive assays will help improve virus disease management in A. sinensis crops.

Fecal rotavirus and adenovirus antigen detection and clinical analysis of children with acute gastroenteritis in a hospital of Beijing City from 2019 to 2022

As a single-center retrospective study, we analyzed the results of rotavirus and human adenovirus antigens in stool samples with colloidal gold immunochromatography method in children with acute gastroenteritis under the age of five who were treated in our hospital from 2019 to 2022. After excluding nonconforming cases and duplicate cases, 2 896 cases were included, of which 559 cases were detected with at least one viral antigen. According to the test results, they were divided into RV positive group, HAdV positive group and RV & HAdV double positive group. The gender, age, seasonal distribution, clinical symptoms and related laboratory tests were compared and analyzed with χ2 test, analysis of variance and nonparametric test. Among the single samples from 2 896 children, the positive rate of RV antigen was 6.21% (180/2 896), the positive rate of HAdV antigen was 10.91% (316/2 896), and the double positive rate of RV & HAdV was 2.18% (63/2 896). The positive rate of HAdV antigen in 2021 was 16.11%, a significant increase compared with 6.20% in 2020. RV infection has obvious seasonality, and spring and winter are the seasons with high incidence of infection (χ2=74.018, P<0.001), while HAdV infection has no obvious seasonality (χ2=2.110, P=0.550), showing sporadic infection throughout the year. The proportions of fever and vomiting symptoms in children with RV infection were significantly higher than those in the HAdV infection group (χ2=40.401, P<0.001; χ2=32.593, P<0.001), but the positive rate of white blood cells in the stool was significantly lower than that in the HAdV infection group (χ2=13.741,P<0.01). In summary, paying attention to the epidemiological changes of RV and HAdV is of great significance for clinical diagnosis and treatment and disease prevention and control.

Rapid detection of apple latent spherical virus infecting Angelica sinensis by gold immunochromatography reverse transcription loop-mediated isothermal amplification assay

Apple latent spherical virus (ALSV; genus: Cheravirus, family: Secoviridae) is capable of infecting Angelica sinensis under natural conditions and causing symptoms of greenish discoloration and mottling, affecting plant growth and causing a reduction in root quality and yield. Virus detection of ALSV is an urgent need for the continued development of angelica industry. Consequently, it is necessary to develop simple, sensitive, and reliable ALSV detection methods. We describe the preparation of polyclonal antibodies with high titer and high specificity using recombinant ALSV coat protein (CP) as the antigen. Using these antibodies, we established and optimized a rapid detection system using colloidal gold immunochromatography assay (GICA) to detect ALSV. A real-time reverse transcription loop-mediated isothermal amplification (RT-LAMP) system with a minimum detection line of 2.72 × 103copys/μl was also developed to detect ALSV. This assay was further enhanced using a combination GICA-RT-LAMP assay. This GICA assay successfully detected ALSV in infected plants without cross reactivity recorded from three other plant viruses. The sensitivity of GICA was the same as that of GICA-RT-PCR, whereas the sensitivity of GICA-RT-LAMP was at least 10-fold higher than that of GICA and GICA-RT-PCR. These methods can detect and identify ALSV under field conditions and accurately measure virus concentration in the laboratory.

Rapid detection and whole class control of quinolone antibiotics in pork based on surface‐enhanced Raman spectroscopy

AbstractThe problem of excessive quinolone antibiotic residues in pork has stimulated great attention from the international community. However, due to the diversity and structural similarity of quinolone antibiotics, it is difficult to perform multi‐residue rapid detection at the same time. Currently, antibiotic multi‐residue detection methods include ultra‐performance liquid chromatography (UPLC) and colloidal gold immunochromatography. However, it cannot be widely used in on‐site rapid detection due to its shortcomings such as the need for high cost and low sensitivity. Herein, we report the use of surface‐enhanced Raman spectroscopy (SERS) technology for the study of similar structures of quinolone antibiotics. A method for whole class control and rapid quantitative detection of all quinolone antibiotics in pork was established. By using the above method, the detection limit of single standard quinolone antibiotics was 10 μg L−1, and the detection limit of the mixed standard was 1 μg L−1, meeting the international requirements for the detection limit of quinolone antibiotics in pork. At last, by adding a variety of quinolone antibiotics to pork, the real detection set‐up was simulated. The recovery of standard addition was 86.6%–95.3%, and the whole class control method has been well applied, which is of great significance for the detection of pork quinolone antibiotics. Compared with colloidal gold immunochromatography, our method has 2.5 times the detection speed, 1/60 times the cost, and can be quantitatively detected. The method is simple, economical, and efficient and has great application value with broad application prospects in the field of rapid detection of pork antibiotics in the future.

Introduction of multilayered magnetic core–dual shell SERS tags into lateral flow immunoassay: A highly stable and sensitive method for the simultaneous detection of multiple veterinary drugs in complex samples

Direct, convenient, and sensitive monitoring of the residues of multiple drugs in complex environments is important but remains a challenge. Here, we report a surface-enhanced Raman scattering (SERS)-based multiplexed lateral flow immunoassay (LFA) that supports the simultaneous and sensitive detection of commonly used drugs kanamycin, ractopamine, clenbuterol, and chloramphenicol in unprocessed complex samples through the dual signal amplification strategy of numerous efficient hotspots and magnetic enrichment. Multilayered magnetic-core dual-shell nanoparticles (MDAu@Ag) with controllable subtle nanogaps were fabricated via the polyethyleneimine-mediated layer-by-layer (LBL) assembly of two layers of Au@Ag satellites onto superparamagnetic Fe3O4 cores and conjugated with specific antibodies as multifunctional tags in the LFA system for rapid capture, separation, and quantitative analysis. Two Raman reporters were embedded in internal nanogaps and modified on the surface of MDAu@Ag for the simultaneous and ultrasensitive detection of four targets on two test lines, which greatly simplified the fabrication and signal reading of SERS-LFA. The proposed assay can rapidly detect multiple drug residues in 35 min with detection limits down to pg/mL level. Moreover, the MDAu@Ag–based SERS-LFA demonstrated better stability, higher throughput, and superior sensitivity (at least 400 times) than traditional colloidal gold immunochromatography, showing its great potential in the field of point-of-care testing.