Showing papers by "Chuanlai Xu published in 2016"
TL;DR: Data indicate that the CD signal is much more sensitive to the concentration of miRNA than the luminescent signal, which is attributed to the strong CD intensity arising from the spin angular momentum of the photon interaction with chiral nanostructures and the plasmonic enhancement of the intrinsic chirality of DNA molecules in the pyramids.
Abstract: Chiral self-assembled nanomaterials with biological applications have attracted great interest. In this study, DNA-driven gold-upconversion nanoparticle (Au-UCNP) pyramids were fabricated to detect intracellular microRNA (miRNA) in real time. The Au-UCNP pyramids are doubly optically active, displaying strong plasmonic circular dichroism (CD) at 521 nm and significant luminescence in 500-600 nm, and therefore can be monitored by both of them. CD will decrease while the luminescence intensity increases in the presence of miRNA. The experimental results show that the CD intensity had an outstanding linear range from 0.073 to 43.65 fmol/10 μg(RNA) and a limit of detection (LOD) of 0.03 fmol/10 μg(RNA), whereas the luminescence intensity ranged from 0.16 to 43.65 fmol/10 μg(RNA) with a LOD of 0.12 fmol/10 μg(RNA). These data indicate that the CD signal is much more sensitive to the concentration of miRNA than the luminescent signal, which is attributed to the strong CD intensity arising from the spin angular momentum of the photon interaction with chiral nanostructures and the plasmonic enhancement of the intrinsic chirality of DNA molecules in the pyramids. This approach opens up a new avenue to the ultrasensitive detection and quantification of miRNA in living cells.
360 citations
TL;DR: Together photothermal therapy and photodynamic therapy are carried out under the guidance of upconversion luminesce, T1 -weighted magnetic resonance, photoacoustics, and computed tomography imaging of tumors in vivo, which exhibit the multifunctional biological applications of the DNA-based self-assemblies.
Abstract: DNA-driven hierarchical core-satellite nanostructures with plasmonic gold nanorod dimers and upconversion nanoparticles are fabricated. Once the core-satellite structure is activated, combined photothermal therapy and photodynamic therapy are carried out under the guidance of upconversion luminesce, T1 -weighted magnetic resonance, photoacoustics, and computed tomography imaging of tumors in vivo, which exhibit the multifunctional biological applications of the DNA-based self-assemblies.
236 citations
TL;DR: This newly developed ICA strip assay is suitable for the on-site detection and rapid initial screening of mycotoxins in cereal samples, facilitating both semi-quantitative and quantitative determination.
Abstract: A semi-quantitative and quantitative multi-immunochromatographic (ICA) strip detection assay was developed for the simultaneous detection of twenty types of mycotoxins from five classes, including zearalenones (ZEAs), deoxynivalenols (DONs), T-2 toxins (T-2s), aflatoxins (AFs), and fumonisins (FBs), in cereal food samples. Sensitive and specific monoclonal antibodies were selected for this assay. The semi-quantitative results were obtained within 20 min by the naked eye, with visual limits of detection for ZEAs, DONs, T-2s, AFs and FBs of 0.1-0.5, 2.5-250, 0.5-1, 0.25-1 and 2.5-10 μg kg(-1), and cut-off values of 0.25-1, 5-500, 1-10, 0.5-2.5 and 5-25 μg kg(-1), respectively. The quantitative results were obtained using a hand-held strip scan reader, with the calculated limits of detection for ZEAs, DONs, T-2s, AFs and FBs of 0.04-0.17, 0.06-49, 0.15-0.22, 0.056-0.49 and 0.53-1.05 μg kg(-1), respectively. The analytical results of spiked samples were in accordance with the accurate content in the simultaneous detection analysis. This newly developed ICA strip assay is suitable for the on-site detection and rapid initial screening of mycotoxins in cereal samples, facilitating both semi-quantitative and quantitative determination.
149 citations
TL;DR: A surface-enhanced Raman scattering (SERS) sensor based on gold nanostar (Au NS) core-silver nanoparticle (Ag NP) satellites was fabricated for the first time to detect aflatoxinB1 (AFB1) and showed superior specificity for AFB1.
Abstract: A surface-enhanced Raman scattering (SERS) sensor based on gold nanostar (Au NS) core–silver nanoparticle (Ag NP) satellites was fabricated for the first time to detect aflatoxinB1 (AFB1). We constructed the SERS sensor using AFB1 aptamer (DNA1)-modified Ag satellites and a complementary sequence (DNA2)-modified Au NS core. The Raman label (ATP) was modified on the surface of Ag satellites. The SERS signal was enhanced when the satellite NP was attached to the Au core NS. The AFB1 aptamer on the surface of Ag satellites would bind to the targets when AFB1 was present in the system, Ag satellites were then removed and the SERS signal decreased. This SERS sensor showed superior specificity for AFB1 and the linear detection range was from 1 to 1000 pg mL−1 with the limit of detection (LOD) of 0.48 pg mL−1. The excellent recovery experiment using peanut milk demonstrated that the sensor could be applied in food and environmental detection.
131 citations
TL;DR: Propeller-like nanoscale assemblies with exceptionally intense chiroptical activity and strong luminescence are prepared using gold nanorods and upconversion nanoparticles showing potential for early disease diagnosis and environmental monitoring.
Abstract: Propeller-like nanoscale assemblies with exceptionally intense chiroptical activity and strong luminescence are prepared using gold nanorods and upconversion nanoparticles. The circular dichroism intensity of the tetramer reached 80.9 mdeg, with g-factor value of 2.1 × 10(-2) . The enhancement factor of upconversion luminescence is as high as 21.3 in aqueous phase. Attomolar bioanalysis of a cancer biomarker with two model is also achieved, showing potential for early disease diagnosis and environmental monitoring.
119 citations
TL;DR: In this article, a sensitive class-specific monoclonal antibody against tetracyclines (TCs) was generated and used to develop an enzyme-linked immunosorbent assay (ELISA) and an immunochromatographic assay for TC, oxytetracyCLine (OTC) detection in milk and honey samples.
Abstract: A sensitive class-specific monoclonal antibody against tetracyclines (TCs) was generated and used to develop an enzyme-linked immunosorbent assay (ELISA) and an immunochromatographic assay for TC, oxytetracycline (OTC), and chlortetracycline (CTC) detection in milk and honey samples. The dynamic range of detection for TC in ELISA was 0.26–2.00 μg L−1 with an IC50 of 0.72 μg L−1. The IC50 value of OTC and CTC was 3.2 and 6.4 μg L−1, respectively. The recovery of TC, OTC, and CTC in milk samples was 82–102, 91–105, and 90–101 %, respectively, and 88–101, 89–101, and 89–95 % in honey samples, respectively. In the immunochromatographic assay, the cutoff values for TC, OTC, and CTC were 15, 15, and 50 μg L−1 in milk, respectively, and 40, 40, and 40 μg L−1 in honey, respectively. The results revealed that ELISA and the immunochromatographic assay can be applied for the rapid and sensitive detection of TC, OTC, and CTC in milk and honey samples.
114 citations
TL;DR: A DNA‐driven nanoparticle self‐assembling pyramid encoding a Raman reporter (Cy5) is reported that detects telomerase in live cells, demonstrating the efficacy of the designed pyramid probe.
Abstract: The highly sensitive and quantitative biodetection of intracellular telomerase is challenging. A DNA-driven nanoparticle self-assembling pyramid encoding a Raman reporter (Cy5) is reported that detects telomerase in live cells. In the presence of the target, the telomerase primer is extended and the inner DNA chain is replaced, leading to the reduction in the surface-enhanced Raman scattering (SERS) signal and the simultaneous recovery of the fluorescent signal. The SERS signal has a linear range for the detection of telomerase in situ of 1 × 10–14 to 5 × 10–11 IU, with a limit of detection of 6.2 × 10–15 IU. The fluorescent signal is used to confirm the intracellular telomerase activity, demonstrating the efficacy of the designed pyramid probe. This biosensing strategy provides a reliable and ultrasensitive protocol for the quantification of biomarkers in living cells.
113 citations
TL;DR: A high yield DNA-driven gold-quantum dot core-satellite is developed for miRNA detection in vitro and vivo, in the presence of the target miRNA, the DNA hairpin between core and satellite is ruined, resulting in the recovery of fluorescence.
Abstract: A high yield DNA-driven gold-quantum dot core-satellite is developed for miRNA detection in vitro and vivo. In the presence of the target miRNA, the DNA hairpin between core and satellite is ruined, resulting in the recovery of fluorescence. The limit of detection for miRNA-21 detection in living cells reaches 296 copies per cell.
93 citations
TL;DR: It was found that the assembly degree and the corresponding SERS signals were in inverse correlation to the BPA concentrations over a wide linear range of 0.001-1ng/mL and the limit of detection was as low as 3.9pg/mL, indicating promising application for the detection of BPA.
67 citations
TL;DR: The ICA strip is useful for the rapid and high-throughout screening of antibiotics in food and environments on-site and the accuracy and reproducibility of the assay were acceptable when tested on food samples.
Abstract: A new immunochromatographic assay (ICA) was developed for the simultaneous screening of five antibiotics that can coexist in milk, namely lincomycin (LIN), gentamicin (GEN), kanamycin (KAN), streptomycin (STR), and neomycin (NEO), using five corresponding monoclonal antibodies (mAbs). The five mAbs were conjugated to colloidal gold nanoparticles (AuNPs), forming AuNP-labeled antibodies, which were placed in a microtiter well after freeze-drying; the five antigens were immobilized separately on five test lines to align with their corresponding AuNP-labeled antibodies. Using this method, the cutoff values for the strip test in milk were 25 ng mL−1 for LIN, 25 ng mL−1 for GEN, 50 ng mL−1 for KAN, 50 ng mL−1 for STR, and 100 ng mL−1 for NEO, which are below the maximum residue levels set by the European Union. Based on the strip reader, the multiplex strip could detect the concentrations of LIN, GEN, KAN, STR, and NEO as low as 2.5 ng mL−1, 2.5 ng mL−1, 2.5 ng mL−1, 2.5 ng mL−1, and 5 ng mL−1 in milk, respectively. The accuracy and reproducibility of the assay were acceptable when tested on food samples. In conclusion, our ICA strip is useful for the rapid and high-throughout screening of antibiotics in food and environments on-site.
63 citations
TL;DR: The SERS-encoded Au@Ag core-shell structure-based immunosensor is promising for the detection of biotoxins, pathogens, and environmental pollutants.
Abstract: A sensitive surface-enhanced Raman scattering (SERS) immunosensor based on the Au nanoparticle (Au NP) shell structure was developed to detect staphylococcal enterotoxin B (SEB) on a microplate. Au NPs modified with 4-nitrothiophenol (4-NTP) and coated with Ag shell of controlled thickness at 6.6 nm exhibited excellent SERS intensity and were used as signal reporters in the detection of SEB. The engaged 4-NTP allowed the significant electromagnetic enhancement between Au NPs and the Ag shell and prevented the dissociation of the Raman reporter. More importantly, 4-NTP-differentiated SERS signals between the sample and microplate. The SERS-based immunosensor had a limit of detection of 1.3 pg/mL SEB. Analysis of SEB-spiked milk samples revealed that the developed method had high accuracy. Therefore, the SERS-encoded Au@Ag core–shell structure-based immunosensor is promising for the detection of biotoxins, pathogens, and environmental pollutants.
TL;DR: Nanoparticle (NP) dimers are composed of two adjacent NPs differing in their components, size, or shape display a rich set of interesting properties as discussed by the authors, which plays a key role in understanding the fundamental mechanisms of their electronic, magnetic and optical properties.
TL;DR: A multiplexed gold‐nanoparticle‐based immunochromatographic (ICT) strip that allows the simultaneous detection of the five main SEs has been reported: SEA, SEB, SEC, SED, and SEE.
Abstract: Staphylococcal enterotoxins (SEs) in food samples can cause severe gastroenteritis even at low doses. Detection of SEs with a single assay would not only improve reliability and portability, but would also save time. In this paper, for the first time, a multiplexed gold-nanoparticle-based immunochromatographic (ICT) strip that allows the simultaneous detection of the five main SEs has been reported: SEA, SEB, SEC, SED, and SEE. Based on the sandwich immunoassay of each SE, a multiplexed ICT strip with five test lines is developed. Sensitive and specific paired monoclonal antibodies facilitate the detection, allowing for high sensitivity and good specificity. The portable biosensor platform can simultaneously detect SEA, SEB, SEC, SED, and SEE at concentrations as low as 2.5, 2.5, 2.5, 1, and 5 ng mL−1, respectively. The entire test can be performed within 15 min and requires no sophisticated instruments except a portable strip reader. To evaluate the multiplexed strip, naturally SEA and SEC contaminated milk samples and pure milk samples spiked with the five SEs are analyzed.
TL;DR: A DNA‐driven gold (Au) heterodimer for intracellular telomerase detection is fabricated and shows an active chiroptical property in the visible region, due to the scissor‐like configuration formed by prolate nanoparticles, which paves the way for chirality‐based ultrasensitive detection of intrACEllular cancer markers.
Abstract: A DNA-driven gold (Au) heterodimer for intracellular telomerase detection is fabricated. The highly biocompatible and intracellularly stable probe shows an active chiroptical property in the visible region, due to the scissor-like configuration formed by prolate nanoparticles. Importantly, the telomerase activity is specifically quantified using circular dichroism intensity in situ after internalization of the heterodimer into cancer cells. Moreover, the results clearly illustrate that this method has a remarkable linear range from 0.8 × 10−12 to 32 × 10−12 IU, and the limit of detection for telomerase activity is 1.7 × 10−15 IU in a single HeLa cell. This strategy paves the way for chirality-based ultrasensitive detection of intracellular cancer markers.
TL;DR: In this paper, gold-silver nanoparticle (AuNP-AgNP) heterodimers were assembled with highly yield as an active SERS substrate, based on antigen-antibody immunoreaction.
TL;DR: It is shown that a DNA zip-fastener structure self-assembled chiral-aptasensor based on gold nanoparticle heterodimers provided an outstanding capability to quantify adenosine-5'-triphosphate (ATP) by addition and that this chiroplasmonic sensor is a promising approach for investigating biogenic biomolecules inside cells and living organisms and for assessing their biological activity.
Abstract: Circular dichroism (CD) has allowed the construction of various chiral nanomaterials for different applications, including biosensing. However, the determination of a simple target-specific, economical, and biocompatible platform using CD with intracellular detection and in situ molecular probing is still required. Here, we show that a DNA zip-fastener structure self-assembled chiral-aptasensor based on gold nanoparticle heterodimers provided an outstanding capability to quantify adenosine-5′-triphosphate (ATP) by addition. The conjugation of two ATP molecules to an adenosine aptamer allowed the formation of a stable ring structure, which formed an ATP-ring adhesive scaffold upon interaction with DNA complementary sequences linked with large gold nanoparticles, the latter were able to drop and result in a decrease in CD signal. We also showed that these low-cytotoxicity and polyethylene glycol (PEG)-steady nanoconjugates were also a one-step incubation technique for the quantification and monitoring of ATP in living cells modified by cell penetrating peptides (TAT) or Cy5. The results showed that the linear intracellular detection range was from 1.5 to 4.2 mM with a limit of detection (LOD) of 0.2 mM. Our findings suggest that this chiroplasmonic sensor is a promising approach for investigating biogenic biomolecules inside cells and living organisms and for assessing their biological activity.
TL;DR: In this paper, a sensitive indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) method and a gold nanoparticle immunochromatographic strip were developed to detect amantadine (AM) in foods.
Abstract: A sensitive indirect competitive enzyme-linked immunosorbent assay(ic-ELISA) method and a gold nanoparticle immunochromatographic strip were developed to detect amantadine (AM) in foods. A novel AM hapten was prepared, and a sensitive monoclonal antibody against AM was developed. The optimum ic-ELISA conditions included a pH of 7.4 and an ionic strength of 1.6% with no organic solvents. The half-inhibition concentration (IC50) value of ic-ELISA was 1.92 ng/ml, with a limit of detection of 0.62 ng/ml. The immunochromatographic test strip method had a visual cut-off value at 5 μg/kg. Chicken samples were spiked with three concentrations of AM (1, 2, and 5 µg/kg) and analysed by ic-ELISA. Good recoveries were obtained (92.3% at 1 µg/kg AM, 116.1% at 2 µg/kg AM, and 91.8% at 5 µg/kg AM).
TL;DR: An overview of recent developments in orientational NPs assemblies, the multiple strategies, biosensors and challenges will be discussed in this review.
TL;DR: A sensitive gold nanoparticle immunochromatographic strip assay and indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) were developed for the detection of ractopamine (RCT), a beta-adrenergic agonist.
Abstract: A sensitive gold nanoparticle immunochromatographic strip assay and indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) were developed for the detection of ractopamine (RCT), a beta-adrenergic agonist. The immunogen and coating antigen were synthesized by the carbodiimide method and conjugated with keyhole limpet hemocyanin and ovalbumin, respectively. The highly sensitive and specific monoclonal antibody was prepared for RCT, with a 50% inhibition concentration of 0.05 ng/ml and had no cross-reactivity with other beta-adrenergic agonists. An ultrasensitive and rapid immunochromatographic strip assay was developed with an RCT cutoff value of 2 ng/ml. Both developed methods can be used for RCT detection in swine urine.
TL;DR: The data obtained show that the strip developed is sensitive and has an advantage of fast test results and simplicity and hence can be adopted for screening of CLB residues in urine samples for mitigation ofCLB residue effects to human health.
Abstract: Being the most used and preferred β2-agonist, clenbuterol (CLB) has been reported to be illegally abused in animal production and breeding as it improves growth rate while inhibiting fat synthesis and deposition leading to buildup of lean muscle. Due to its potential hazard to human health, causing food poisoning that can be fatal, it has been forbidden as a growth promoter for food-producing animals in most countries including China. Therefore, frequent monitoring of CLB abuse is necessary for consumer safety against its residues. We therefore report development of a monoclonal antibody and lateral flow test strip for sensitive detection of CLB in urine samples. In this investigation, male BALB/C mice were first immunized for antibody production. Thereafter, gold nanoparticles were utilized for antigen and antibody immobilization during construction of the strip. Under optimized conditions, the cut-off limit of the test strip was found to be 2.5 and 5 ng/g in phosphate-buffered saline (PBS) and urine usi...
TL;DR: An innovative competitive immunochromatographic strip sensor was developed for rapid detection of Salmonella based on a genus-specific antilipopolysaccharide (LPS) monoclonal antibody and the heterogeneous coating antigen of a LPS-bovine serum albumin conjugate.
Abstract: In this study, an innovative competitive immunochromatographic strip sensor was developed for rapid detection of Salmonella based on a genus-specific anti- lipopolysaccharide (LPS) monoclonal antibody (mAb) and the heterogeneous coating antigen of a LPS-bovine serum albumin conjugate. Gold nanoparticles labeled anti-LPS mAb specifically reacted with the conserved outer core of the Salmonella LPS in the sample and the color formed on the T line was negatively correlated with the number of Salmonella cells. The sensitivity of Ra mutant LPS (without O-specific chains but has the conserved outer core) was 25 ng mL–1, which explained the detection of Salmonella at the genus level. Based on the gray values on the test line, the limit of detection of Salmonella was 103 colony-forming unit (CFU) for all twelve typical strains of Salmonella . The analysis of common Gram-negative and Gram-positive bacteria demonstrated that the strip assay was specific to Salmonella . A milk sample test showed that Salmonella at a low level (1–5 CFU mL–1) was detected without complex biochemical confirmation steps, sophisticated instruments and professional training.
TL;DR: In this paper, a monoclonal antibody against FA was prepared for the development of indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and lateral-flow immunochromatographic assay (ICA) strip.
Abstract: Folic acid (FA) is an important vitamin for human growth and development, especially for pregnant women. A sensitive, rapid, and accurate FA detection method is required to assess the nutritional quality and safety of foods. A monoclonal antibody against FA was prepared for the development of indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and lateral-flow immunochromatographic assay (ICA) strip. The 50% inhibitory concentration and limit of detection of ic-ELISA were 0.12 and 0.018 ng/ml, respectively. The visual limit of detection and cut-off values of the lateral-flow ICA strip were 0.5 and 2.5 ng/ml, respectively. Using the ICA strip, FA recovery rates were 89–98% from energy drinks and 73–87% for milk samples and were in good agreement with those obtained from the conventional microbiological assay method. Our developed methods are sensitive, convenient, effective, and suitable for on-site detection and rapid mass screening of food samples.
TL;DR: An immunochromatographic assay was developed and used to detect testosterone in milk samples, which showed high sensitivity to testosterone and could be used as a fast and cost-effective alternative tool for screening for endocrine-disrupting compounds.
Abstract: A monoclonal antibody against testosterone was produced and used to construct an indirect enzyme-linked immunosorbent assay (ELISA) and immunochromatographic assay. As testosterone could not be linked to the protein directly, testosterone and methyltestosterone were first derived by using carboxymethoxylamine hemihydrochloride (CMO) to introduce a carboxyl group at the carbonyl group position. Then the resulting testosterone-3-CMO was coupled to the carrier protein to form the immunogen, using the 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)/N-Hydroxysuccinimide (NHS) method. A cell line obtained by cell fusion secreted an antibody which showed high affinity with testosterone. Based on methyltestosterone-3-CMO-ovalbumin (OVA) as the competitive antigen, the ELISA we developed showed high sensitivity to testosterone, with IC50 of 0.11 ng/mL. The results of cross-reactivity testing showed that the antibody was specific to testosterone. Based on this antibody, an immunochromatographic assay w...
TL;DR: In this article, a sensitive indirect competitive enzyme-linked immunosorbent assay and rapid immunochromatographic strip (ICS) test were developed to simultaneously detect tyl and tilmicosin (TIM) based on an innovative hapten.
Abstract: Tylosin (TYL) and tilmicosin (TIM) are macrolide antibiotics, and maximum residue limits (MRLs) have been set to control their illegal usage in food. We developed a sensitive indirect competitive enzyme-linked immunosorbent assay and rapid immunochromatographic strip (ICS) test to simultaneously detect TYL and TIM based on an innovative hapten (TYL-carboxymethoxylamine hemihydrochloride). The monoclonal antibody 2B3 was obtained with the isotype IgG1, and TYL and TIM had half maximal inhibitory concentrations of 0.57 and 2.10 ng/ml, respectively. The cross-reactivity values were 100%, 27.57%, 97.43%, and 62.42% for TYL, TIM, desmycosin, and acetylisovaleryl tylosin, respectively. By optimizing, the standard dilution buffer was based on 0.8% NaCl, pH 7.4 and 5% acetonitrile. The recoveries ranged from 89.37% to 112.00% in the honey samples, which suggests that the assay would be reliable in the analysis of real honey samples. In addition, an ICS was developed for qualitative, semi-quantitative, and...
TL;DR: A rapid and sensitive indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and a gold nanoparticle immunochromatographic (ICA) strip test for detecting RBV in chicken muscles are developed.
Abstract: The use of ribavirin (RBV) as an antiviral drug for livestock has been prohibited in China, the USA, and many other countries. In this study, we developed a rapid and sensitive indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and a gold nanoparticle immunochromatographic (ICA) strip test for detecting RBV in chicken muscles. Under the optimum assay conditions, where the assay employed phosphate-buffered saline at pH 7.4, no acetonitrile, and an ionic strength of 0.8%, the quantitative working range was 1.43–26.47 ng/ml with an IC50 of 6.15 ng/ml. The recovery rate for RBV in real samples ranged from 82.1% to 112.3%. The immunochromatographic test strip method had a visual cutoff value of 50 μg/kg. Given their high recovery rates and good sensitivity, the proposed ic-ELISA and ICA methods could be useful for the RBV analysis in chicken tissue samples.
TL;DR: Results indicated that the developed icELISA was a fast and efficient method for detecting AA in food and cross-reactivity with other analogues was lower than 10%.
Abstract: Acrylamide (AA) is formed spontaneously in heated foodstuffs and is a focus of concern in many people due to safety. In this study, we developed an indirect competitive enzyme-linked immunosorbent assay (icELISA) based on a monoclonal antibody (MAb) to detect a derivative, which was generated from 4-mercaptobenzoic acid (4-MBA). As AA is a very small molecule (71.08 Da) and cannot elicit a homologous monoclonal antibody, we coupled the AA derivative (AA-4-MBA) to a carrier protein such as bovine serum albumin (BSA) and ovalbumin (OVA). The conjugates were used as the immunogen and coating antigen. A rapid and sensitive icELISA against AA-4-MBA was obtained by optimizing the experimental parameters. The MAb which had no specificity for AA or 4-MBA, but had high affinity for AA-4-MBA, had a satisfactory IC50 of 32 ng/ml and a limit of detection of 8.87 ng/ml. The quantitative working range was 8.87–112.92 ng/ml (IC20 to IC80). Cross-reactivity with other analogues was lower than 10%. These results i...
TL;DR: These findings demonstrated that the immunoassay is able to detect FQs in milk samples.
Abstract: A heterologous immunoassay has been developed for the determination of sarafloxacin (SRFX) and its analogue residues in milk. A novel hapten with molar mass 499 g was synthesised by introducing a six carbon molecule [6-bromohexanoic acid (BR)] as a spacer arm. This greatly improved the effect of SRFX inducing immune response in mice and enhanced the chance of producing a monoclonal antibody capable of recognising analogues to SRFX. The synthesised hapten [7-(4-(5-carboxypentyl)piperazin-1-yl)-6-fluoro-1-(4-fluorophenyl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (SRFX-BR)], to induce an immune response, was conjugated to bovine serum albumin (BSA) (SRFX-BR-BSA) via the carbodiimide active ester method while the mixed anhydride reaction was used to prepare the coating antigen [SRFX conjugated to ovalbumin (OVA) (SRFX-OVA)] to pursue the heterologous sensitivity. Based on the checkerboard titration, an indirect competitive enzyme-linked immunosorbent assay (icELISA) was developed for the quantitative detection of SRFX and three of its analogues in cattle milk. After optimisation, the immunoassay was found to tolerate up to 15% methanol at a physiological pH (7.4) and a salt (NaCl) concentration of 1.2%. The results of this assay showed a good cross-reactivity to tosufloxacin (64.94%), nadifloxacin (58.14%), pazufloxacin (42.02%), fleroxacin (40.04%), pipemidic acid (34.25%), and ofloxacin (20.08%). These findings demonstrated that the immunoassay is able to detect FQs in milk samples.
TL;DR: A simple, rapid, and sensitive immunochromatographic strip was produced based on the monoclonal antibody, with a qualitative visual limit of detection of 2 ng/ml in water samples and 10”ng/ ml in fish samples, indicating its potential utility in monitoring pentachlorophenol in the field.
Abstract: A sensitive monoclonal antibody for targeting pentachlorophenol was prepared with an immunization procedure and cell fusion. The antibody was characterized with an indirect competitive enzyme-linked immunosorbent assay (ELISA), which had an IC50 of 0.2 ng/ml for pentachlorophenol under optimized conditions. The cross-reactivity of the ELISA to related compounds was very low. The recovery of pentachlorophenol was 99.2–105% in water samples and 89–110.9% in fish samples. A simple, rapid, and sensitive immunochromatographic strip was produced based on the monoclonal antibody, with a qualitative visual limit of detection of 2 ng/ml in water samples and 10 ng/ml in fish samples, indicating its potential utility in monitoring pentachlorophenol in the field.
TL;DR: In this paper, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and immune-chromatographic strip were developed to detect these compounds based on monoclonal antibody.
Abstract: Hexestrol (HES) and Diethylstilbestrol (DES) are synthetic hormones, which have been found abuse use in animal-origin food production. We developed an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and immune-chromatographic strip to detect these compounds based on monoclonal antibody. Under optimized conditions, the half-inhibition concentration (IC50) values of ic-ELISA were 0.15 µgL−1 and 0.23 µgL−1 for HES and DES, respectively. Spiked milk samples were analyzed. The recovery of both synthetic hormones in the milk samples was 60.48–102.19% (HES) and 89.34–100.16% (DES). In immune-chromatographic assay, the visual cutoff values at 0.5 and 1.0 µgL−1 respectively for HES and DES, which allow us to detect milk samples of a concentration low to 10 µgL−1 for HES and 15 µgL−1 for DES.
TL;DR: In this paper, an immunochromatographic strip was developed for the semi-quantitative and quantitative detection of biotin in milk and milk products, and the results were validated by the microbiological assay method.
Abstract: An immunochromatographic strip was developed for the semi-quantitative and quantitative detection of biotin in milk and milk products. This detection system was developed based on a sensitive and specific monoclonal antibody produced in our laboratory. The semi-quantitative results, which were visually obtained in 20 min, revealed that the visual limit of detection was 2.0 μg/100 g with a cut-off value of 8.0 μg/100 g. The quantitative results, which are obtained with a strip scan reader, revealed that the calculated limit of detection was 0.32 μg/100 g with a linear range of 0.65–68 μg/100 g. Biotin contents in milk and milk products were determined by using the developed immunochromatographic strip, and the results were validated by the microbiological assay method. Our developed immunochromatographic strip system is suitable for the on-site detection and rapid screening of biotin in food samples.