Development of enzyme-linked immunosorbent assay (ELISA) for the detection of neomycin residues in pig muscle, chicken muscle, egg, fish, milk and kidney

Ampicillin detection using absorbance biosensors utilizing Mn-doped ZnS capped with chitosan micromaterials

The detection of ampicillin plays a crucial role in managing and monitoring its usage and resistance. This study introduces a simple and effective biosensor for ampicillin detection, utilizing the unique absorbance features of Mn-doped ZnS capped by chitosan micromaterials in conjunction with β-lactamase activity. The biosensors can detect ampicillin concentrations from 13.1 to 72.2 μM, with a minimum detection limit of 2.93 μM for sensors based on 300 mg/L of the sensing material. In addition, these sensors show high specificity for ampicillin over other antibiotics such as penicillin, tetracycline, amoxicillin, cephalexin, and a non-antibiotic-glucose. This specificity is demonstrated by an enhancing effect when beta-lactamase is used, as opposed to a quenching effect observed at 340 nm in the absorbance spectrum when no beta-lactamase is present. This research highlights the potential of affordable chitosan-capped Mn-doped ZnS micromaterials for detecting ampicillin through simple absorbance measurements, which could improve the monitoring of antibiotics in both clinical and environmental settings.

A New Peptide Nucleic Acid Fluorescence In Situ Hybridization Probe for the Specific Detection of Salmonella Species in Food Matrices

Salmonella spp. is among the most central etiological agents in foodborne bacterial disorders. To identify Salmonella spp., numerous new molecular techniques have been developed conversely to the traditional culture-based methods. In this work, a new peptide nucleic acid fluorescence in situ hybridization (PNA-FISH) method was developed for the specific detection of Salmonella species, allowing a faster analysis compared with the traditional methods (ISO 6579-1: 2017). The method was optimized based on a novel PNA probe (SalPNA1692) combined with a blocker probe to detect Salmonella in food samples through an assessment of diverse-rich and selective enrichment broths. Our findings indicated that the best outcome was obtained using a 24-h pre-enrichment step in buffered peptone water, followed by RambaQuick broth selective enrichment for 16 h. For the enrichment step performance validation, fresh ground beef was artificially contaminated with two ranges of concentration of inoculum: a low level (0.2-2 colony-forming units [CFUs]/25 g) and a high level (2-10 CFUs/25 g). The new PNA-FISH method presented a specificity of 100% and a detection limit of 0.5 CFU/25 g of food sample, which confirms the great potential of applying PNA probes in food analysis.

Characterization, specific recognition, and the performance in fish matrix of a shark-derived single-domain antibody against enrofloxacin

The third generation of genetic engineering antibodies, single-domain antibodies, have been widely reported as potential biomaterials in recognizing small molecular hazards. In this study, a shark-derived single-domain antibody was used as the recognition element for the first time to detect enrofloxacin (ENR), one of the most representative hazards in aquaculture. An ENR-specific clone named 2E6 was isolated by phage display technology. Experimental results proved that 2E6 ssdAb showed high affinity to ENR-PEI complete antigen, with the highest OD₄₅₀ value of 1.348 in binding ELISA. Through icELISA, it was determined that the IC₅₀ of 2E6 ssdAb to ENR was 19.230 ng/mL, while the IC₁₀ was 0.975 ng/mL, with rare recognition to other fluoroquinolones, which showed high sensitivity and specificity to ENR. The 2E6 ssdAb also performed excellently in fish matrix immunoassay. Results showed that the ENR-negative fish matrix did not seriously interfere with the recognition of 2E6 ssdAb to ENR-OVA, with the matrix index between 4.85% and 11.75%, while the results of icELISA in ENR-spiked fish matrix showed that 2E6 ssdAb could recognize the target ENR in different ENR-spiked concentrations of the fish matrix (10-1000 ng/mL), with the recovery between 89.30% and 126.38% and the RSD between 1.95% and 9.83%. This study broadens the application scenario of shark-derived single-domain antibodies as small molecule recognition biomaterials, providing a new recognition element on ENR detection for immunoassay.

The effect of chlorophyll on the enzyme-linked immunosorbent assay (ELISA) of procymidone in vegetables and the way to overcome the matrix interference

BACKGROUND

There is now an increasing demand for the immunoassay of procymidone residue in foodstuffs. However, the matrix interference could significantly affect the analysis. Till now there is no detailed information on the source of the interference and the mechanism involved, which greatly limits the real application of these techniques.

RESULTS

Significant matrix effect was observed in the enzyme-linked immunosorbent assay (ELISA) of procymidone in negative vegetable samples (leek, broccoli and cucumber). By the investigation with both vegetable extracts and standard solutions, the chlorophyll was confirmed as an important source of the matrix effect. Therefore, a new strategy was proposed for the pretreatment based on the exploitation of 5-sulfosalicylic acid. It was demonstrated to effectively eliminate chlorophyll and exhibited little effect on procymidone and the competitive indirect ELISA (ci-ELISA) performance. The established technique was validated with different vegetables. With the spiking concentration of procymidone investigated, the recovery rate of ci-ELISA was 71.52-120.37%, and the relative standard deviation was 4.05-17.61%.

CONCLUSION

Chlorophyll was for the first time illuminated as an important source of matrix interference to the immunoassay of procymidone in vegetables. A new pretreatment based on 5-sulfosalicylic acid was established to remove chlorophyll and therefore eliminate the matrix effect. Validated with different vegetable samples, the new technique was demonstrated much better efficiency in comparison to conventional methods, which indicated its promising application for the development of immunoassays of herb-origin samples. © 2021 Society of Chemical Industry.

Antibiotic Use in Livestock and Residues in Food-A Public Health Threat: A Review

The usage of antibiotics has been, and remains, a topic of utmost importance; on the one hand, for animal breeders, and on the other hand, for food safety. Although many countries have established strict rules for using antibiotics in animal husbandry for the food industry, their misuse and irregularities in compliance with withdrawal periods are still identified. In addition to animal-origin foods that may cause antibiotic residue problems, more and more non-animal-origin foods with this type of non-compliance are identified. In this context, we aim to summarize the available information regarding the presence of antibiotic residues in food products, obtained in various parts of the world, as well as the impact of consumption of food with antibiotic residues on consumer health. We also aim to present the methods of analysis that are currently used to determine antibiotic residues in food, as well as methods that are characterized by the speed of obtaining results or by the possibility of identifying very small amounts of residues.

Development of a Broad-Specific Competitive ELISA for First-Generation Cephalosporin Antibiotics in Animal-Derived Foods Samples

The abuse of antibiotics, such as the cephalosporins in livestock and aquaculture productions, usually causes the widespread antibiotic resistance due to their growth-promoting effects. In this study, cephalexin was chosen as the hapten molecule to prepare a broad-spectrum rabbit polyclonal antibody for cephalosporin antibiotics. The obtained antibody exhibited broad cross-reactivity ranging from 0.05% to 100% with 10 cephalosporins. Based on this antibody, we developed a broad-specific indirect competitive ELISA (ic-ELISA) for cefalexin, cefradine, cefadroxil and cefazolin with the half maximal inhibitory concentration (IC₅₀) ranging from 0.72 to 2.99 ng/mL in working buffer. For animal-derived food samples with spiked cephalosporins, the ic-ELISA exhibited an excellent recovery ranging from 72.3% to 95.6%. To verify the accuracy of this proposed ic-ELISA, its detection performance was evaluated utilizing the high-performance liquid chromatography with satisfactory results. This study confirmed that: firstly, the prepared antibody can be used as a class-specific recognition element to develop immunoassays for cephalosporin antibiotics; and secondly, the developed ic-ELISA provided a new tool for broad-spectrum detection of first-generation cephalosporins in animal-derived foods.

Recent advances in aptamer-based sensors for aminoglycoside antibiotics detection and their applications

Aminoglycoside antibiotics (AAs) have been extensively applied in medical field and animal husbandry owing to desirable broad-spectrum antibacterial activity. Excessive AAs residues in the environment can be accumulated in human body through food chain and cause detrimental effect on human health. The establishment of highly specific, simple and sensitive detection methods for monitoring AAs residues is highly in demand. Aptasensor using aptamer as the biological recognition element is the efficient and promising sensing method for detection of AAs. In this review, we have made a summary of specific aptamers sequences against AAs. Subsequently, we provide a systematical and comprehensive overview of modern techniques in aptasensors for detection of AAs according to optical aptasensors as well as electrochemical aptasensors and further summarize their advantages and disadvantages to compare their applications. In addition, we present an overview of practical applications of aptasensors in sample detection of AAs. Moreover, the current challenges and future trends in this field are also included to reveal a promising perspective for developing novel aptasensors for AAs.

Advances in Gold Nanoparticles-Based Colorimetric Aptasensors for the Detection of Antibiotics: An Overview of the Past Decade

Misuse of antibiotics has recently been considered a global issue because of its harmful effects on human health. Since conventional methods have numerous limitations, it is necessary to develop fast, simple, sensitive, and reproducible methods for the detection of antibiotics. Among numerous recently developed methods, aptasensors are fascinating because of their good specificity, sensitivity and selectivity. These kinds of biosensors combining aptamer with colorimetric applications of gold nanoparticles to recognize small molecules are becoming more popular owing to their advantageous features, for example, low cost, ease of use, on-site analysis ability using naked eye and no prerequisite for modern equipment. In this review, we have highlighted the recent advances and working principle of gold nanoparticles based colorimetric aptasensors as promising methods for antibiotics detection in different food and environmental samples (2011–2020). Furthermore, possible advantages and disadvantages have also been summarized for these methods. Finally, the recent challenges, outlook, and promising future perspectives for developing novel aptasensors are also considered.

Measurement of methotrexate in human cerebrospinal fluid using a chemiluminescence immunoassay intended for serum and plasma matrices

Background

The concentration of MTX in blood is often measured quickly and easily by immunoassays. Thus, immunoassays may facilitate the easy determination of the concentration of MTX in the cerebrospinal fluid (CSF). In this study, we measured methotrexate (MTX) concentrations in the CSF using a high‐performance liquid chromatography (HPLC) method intended for analyzing CSF matrices and a chemiluminescence immunoassay (CLIA) method intended for assessing serum and plasma matrices and verified the differences in the results of the two methods.

Methods

HPLC analysis for MTX in the CSF was performed using a Prominence UFLC system with a C18 column. The HPLC method was validated in accordance with the 2018 FDA guideline. The CLIA method was performed using an ARCHITECT i1000SR system intended for serum and plasma matrices. A total of 47 CSF samples (14 clinical and 33 spiked specimens) were analyzed using the two methods.

Results

The HPLC method passed the validation criteria. The concentration of MTX in the same sample, determined using the HPLC and CLIA methods, differed proportionally; the percent difference in the concentrations averaged −23.0% (95% confidence interval: −36.9% to −9.1%) as revealed by the Bland‐Altman plot. The relationship between the measured values, evaluated using the Passing‐Bablok regression, was as follows: HPLC = 1.205 × CLIA – 0.024.

Conclusion

The equation deduced in this study can be used to correct the concentration of MTX measured using the CLIA method.

Identification of chicken meat quality via rapid array isoelectric focusing with extraction of hemoglobin and myoglobin in meat sample

Isoelectric focusing (IEF) has been used for determination of meat quality with high stability analysis. However, it still suffered from time-consuming, laborious and cost-effective performances, e.g., 3 h protein extraction, more than 10 h rehydration time, 5-12 h focusing time, and imaging of protein band. To overcome these issues, a speedy extraction of colorful proteins was developed by controlling extraction and centrifugation of 0.2g sample within 10 min and 15 min respectively; a rapid analytical method was designed by using a quick array IEF with 25 min rehydration, 7 min focusing, 2 min online scanning and imaging of focused proteins. The total analytical time was well controlled within 1 h, significantly less than the traditional IEF time of 24 h. To demonstrate the proposed method, 18 chickens were classified into three groups, e.g., the normal slaughtering, death treatment underwater, and death with infection via the New castle disease (NDV) virus. The experiments demonstrated that two Mb bands with pI 6.8 and 7.4 were present in slaughtered chickens, while four other bands with pI 6.83, 6.95, 7.09, and 7.13 were observed in abnormal chicken. The additional four proteins bands were identified by western blot (WB) as hemoglobin proteins. Furthermore, array Immobilized pH Gradient (IPG) has high sensitivity (absolute LOD of Mb and Hb were 1.3 ng and 5.5 ng), fair stability (RSD values of 2.32%, 2.27%, and 1.69%) for slaughtered, drowned, NDV-infected chickens for intra-day and (2.94%, 1.66%, and 1.07%) for inter-days, and good recovery (100%, 98.25% and 99.75%). Finally, the developed method could be used for the identification of chicken meat quality with less time and small volume reagents consuming.

Biosensors for the Detection of Antibiotics in Poultry Industry—A Review

Antibiotic resistance is emerging as a potential threat in the next decades. This is a global phenomenon whereby globalization is acting as a catalyst. Presently, the most common techniques used for the detection of antibiotics are biosensors, ELISA and liquid chromatography-mass spectrometry. Each of these techniques has its benefits as well as drawbacks. This review aims to evaluate different biosensing techniques and their working principles in order to accurately, quickly and practically detect antibiotics in chicken muscle and blood serum. The review is divided into three main sections, namely: a biosensors overview, a section on biosensor recognition and a section on biosensor transducing elements. The first segment provides a detailed overview on the different techniques available and their respective advantages and disadvantages. The second section consists of an evaluation of several analyte systems and their mechanisms. The last section of this review studies the working principles of biosensing transducing elements, focusing mainly on surface plasmon resonance (SPR) technology and its applications in industries.

The effect of fish matrix on the enzyme-linked immunosorbent assay of antibiotics

BACKGROUND

The matrix effect is considered to be a problem in the immunoassay of foodstuffs. However, information on the interference from aquatic products, as well as the mechanism involved, is very limited. In this study, using three flatfishes (Scophthalmus maximus, Paralichthys olivaceus and Cymoglossus robustus) as samples, the effect of the fish matrix on the competitive indirect enzyme-linked immunosorbent assay (ci-ELISA) of antibiotic (norfloxacin) residues was investigated. The mechanism of the observed matrix effect is also preliminarily discussed.

RESULTS

Within the working range of the calibration curves, a significant (P = 0.05) but irregular variation in the inhibition ratio was observed in the presence of fish extracts. Further experiments revealed that such a matrix effect could be caused by some water-soluble fish proteins with a wide range of molecular weight (from below 14.4 kDa to about 116.0 kDa), and the ions from fish muscles may also contribute to the interference. The results of western blotting indicated that some fish protein components might effectively bind with antibody reagents used.

CONCLUSION

Significant interference in the immunoassay of norfloxacin was observed in the presence of fish matrix. Some proteins and ions were demonstrated to contribute to the matrix effect investigated. Although the detailed mechanism is still unclear, the non-specific interaction between fish proteins and immunoglobulin G (IgG) or horseradish peroxidase (HRP) labelled IgG was assumed to be an important source of the matrix effect in immunoassays.

Electrochemical sensor using neomycin-imprinted film as recognition element based on chitosan-silver nanoparticles/graphene-multiwalled carbon nanotubes composites modified electrode

A novel imprinted electrochemical sensor for neomycin recognition was developed based on chitosan-silver nanoparticles (CS-SNP)/graphene-multiwalled carbon nanotubes (GR-MWCNTs) composites decorated gold electrode. Molecularly imprinted polymers (MIPs) were synthesized by electropolymerization using neomycin as the template, and pyrrole as the monomer. The mechanism of the fabrication process and a number of factors affecting the activity of the imprinted sensor have been discussed and optimized. The characterization of imprinted sensor has been carried out by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). The performance of the proposed imprinted sensor has been investigated using cyclic voltammetry (CV) and amperometry. Under the optimized conditions, the linear range of the sensor was from 9×10(-9)mol/L to 7×10(-6)mol/L, with the limit of detection (LOD) of 7.63×10(-9)mol/L (S/N=3). The film exhibited high binding affinity and selectivity towards the template neomycin, as well as good reproducibility and stability. Furthermore, the proposed sensor was applied to determine the neomycin in milk and honey samples based on its good reproducibility and stability, and the acceptable recovery implied its feasibility for practical application.

Validation of an enzyme-linked immunosorbent assay for qualitative screening of neomycin in muscle, liver, kidney, eggs and milk

A rapid and sensitive enzyme-linked immunosorbent assay (ELISA) was used for the qualitative screening analysis of neomycin in food of animal origin (muscle, liver, kidney, eggs and milk) at levels corresponding to the European Union maximum residue limit (MRL) set for this substance. The method validation was performed according to the criteria of Commission Decision 2002/657/EC established for qualitative screening methods. In this regard, the following parameters were determined: detection capability (CCβ), specificity, detection limit (LOD), quantification limit (LOQ), recovery, precision, linearity and ruggedness. LODs ranged from 5.7 microg kg(-1) in kidney to 29.3 microg kg(-1) in milk; LOQs ranged from 11.4 microg kg(-1) in kidney to 59.7 microkg(-1) in eggs. The recoveries from spiked samples at the MRL, half the MRL and double the MRL levels ranged from 65.8% to 122.8%, with a coefficient of variation (CV) between 5.9% and 28.6%. The CCβ value was less than the MRL for all examined matrices. Moderate variations of some critical factors in the sample pretreatment for muscle, milk and eggs were deliberately introduced for ruggedness evaluation and had a slight but not statistically significant effect on method performance. The proposed method is suitable for qualitative screening analysis of neomycin in the above-mentioned food in conformity with current European Union performance requirements.

Direct competitive enzyme-linked immunosorbent assay (ELISA) for rapid screening of anisakid larvae in seafood

BACKGROUND

Anisakid larvae are one of the most important pathogenic parasites in marine products; however, simple and rapid analytical techniques for them are still very limited. In this research, based on specific rabbit polyclonal antibodies which were raised against crude extracts of Anisakis larvae, purified by protein A affinity chromatography and labeled with horseradish peroxidase, a direct competitive enzyme-linked immunosorbent assay (ELISA) was developed and validated for detection of anisakid larvae in seafood.

RESULTS

The established method exhibited a broad selectivity to Anisakis larvae and Pseudoterranova larvae, and the lowest detection limit to them was estimated to be about 5 parasites kg(-1) in food matrix. Using Pseudopleuronectes yokohamae, Scomberomorus niphonius and Ommastrephes bartrami as samples and within spiking concentrations from 20 to 100 larvae kg(-1), the determination recovery for Anisakis larvae and Pseudoterranova larvae ranged from 77.8% to 107.0%, with relative standard deviations all less than 20%.

CONCLUSION

The results allowed us to suggest the established direct competitive ELISA as an effective analytical tool for fast screening of anisakid larvae in sea foods.

Cephalexin residue detection in milk and beef by ELISA and colloidal gold based one-step strip assay

An evaluation of a rapid enzyme-linked immunosorbent assay (ELISA) and colloidal gold based one-step strip assay for cephalexin (CEX) residue detection in milk and beef is described. A monoclonal antibody (mAb) against CEX was produced using cephalexin-bovine serum albumin (CEX-BSA) conjugate as the immunogen, which exhibited no cross-reactivity with applied chemicals in the studied concentration range. The detection limit of rapid ELISA was calculated as 0.39 microg/kg in PBS and 19.5 microg/kg in beef and milk, which was quite lower than the European Union Maximum Residue Limit (MRL) of 100 microg/kg in milk and 200 microg/kg in muscle. Spiked samples were detected with a mean recovery of 82.8-124% and coefficient of variation of 4.88-25%, which indicated a good agreement with the spiked concentration. Accuracy and reproducibility were determined using spiked samples with four different final concentrations of 1, 2, 5, and 10 microg/kg of CEX (n = 7). Mean intra-assay variation of 6.67% and inter-assay variation of 10.66% were obtained. In contrast, the strip test for CEX had a visual detection limit of 0.5 microg/kg, which could be evaluated within 3-10 min. However, positive samples should be further quantified by more sensitive and accurate competitive indirect ELISA method. In conclusion, the described strip test is rapid, simple, and cost-effective as well as sensitive and specific enough for reliable and accurate on-site screening.