查找使用阿拉丁产品的科研文献

A highly sensitive aptasensor for OTA detection based on hybridization chain reaction and fluorescent perylene probe

Bin Wang,Yuanya Wu,Yanfen Chen,Bo Weng,Liqun Xu,Changming Li

An optical aptasensor was developed for ultrasensitive detection of ochratoxin A (OTA) based on hybridization chain reaction (HCR) amplification strategy and fluorescent perylene probe (PAPDI)/DNA composites. Dendritic DNA concatamers were synthesized by HCR strategy and modified on magnetic nanoparticles through aptamer as medium. A large amount of PAPDI probe aggregated under the induction of DNA concatamers and caused fluorescence quenching . In the presence of OTA, the PAPDI/DNA composites were released from magnetic nanoparticles due to the strong affinity between aptamer and OTA. In ethanol, PAPDI monomers disaggregated and produced strong fluorescence. The present method displays excellent sensitivity and selectivity towards OTA.

Structure-switching locked hairpin triggered rolling circle amplification for ochratoxin A (OTA) detection by ICP-MS

Jie Zhang,Yuheng Lu,Wei Gao,Peng Yang,Nansheng Cheng,Yanwen Jin,Junbo Chen

Ochratoxin A (OTA) is usually found in the contaminated cereal food that its trace concentration would cause severe carcinogenicity and neurotoxicity. Herein, a recognition-triggered structure switching-based element spectrometric assay was proposed for ultrasensitive and highly specific detection of OTA. OTA aptamer was first adapted into a primer for the formation of a locked hairpin (LHP), and followed by attachment on the surface of magnetic beads (MBs). In the presence of OTA, the binding event between OTA molecule and its aptamer induced the liberation of the primer for that is otherwise unable to spontaneously structure-switching. For the rolling circle amplification (RCA), thereby a dumbbell structure was designed as the template (DT). The hybridization of the dumbbell template with free primer initiates the rolling circle amplification along with the production of repeated sequences. To obtain the signal output, the DNA-AuNP tag was prepared which contained the complementary sequences with RCA products. Thus, each tag can hybridize with the repeated sequences derived from the RCA, enabling the formation of detectable signal by the following ICP-MS measurement. Such design can translate a single recognition event into numerous AuNPs, enabling amplified detection of OTA. Taking advantage of this principle, the OTA in real sample (AFP, PSA) can be quantified at femtomolar concentration and it can be expanded into application in food safety inspection.

Competitive ELISA based on pH-responsive persistent luminescence nanoparticles for autofluorescence-free biosensor determination of ochratoxin A in cereals

Wang Yinghui,Yu Ling,Zhang Hui,Zhu Runzhi,Meng Zhe

An accurate and sensitive competitive enzyme-linked immunosorbent assay (ELISA) based on persistent luminescence nanoparticles Zn 2 GeO 4 :Mn 2+ , Eu 3+ (ZGME) was developed for detecting ochratoxin A (OTA), a powerfully toxic mycotoxin usually found in grains. As a signal output element of autofluorescence-free biosensors, ZGME can be integrated into ELISA with glucose oxidase (GOx)-binding OTA molecules due to its excellent pH-responsive persistent luminescence. In the absence of OTA, the OTA-GOx conjugate was captured by the anti-OTA monoclonal antibody (anti-OTA mAb) pre-coated on the 96-well plate. The results indicate a decrease in the pH value of the solution, which triggered the quenching of ZGME luminescence due to GOx-dependent gluconic acid production. The presence of OTA inhibited the binding of OTA-GOx on the plate, thus decreasing the production of gluconic acid and increasing the persistent luminous intensity of ZGME. Under the optimized concentrations of anti-OTA mAb and OTA-GOx, quantitative determination of OTA was achieved by plotting the increase or decrease in persistent luminescence intensity of ZGME at 535 nm. In this study, the linear range was from 0.1 μg L −1 to 63 μg L −1 , and the limit of detection (LOD) was as low as 0.045 μg L −1 . In five food samples (corn grit, brown rice, soybean, rice, and wheat), the results exhibited good stability and repeatability, with a recovery range from 81.3% to 94.4% and a relative standard deviation (RSD) of less than 4.2%. Hence, the established method provides a sensitive, accurate, and autofluorescence-free approach for the determination of OTA in different grain samples.

A smartphone-coupled electrochemical biosensor based on DNA tetrahedral scaffolds for simultaneous quantification of AFB1 and OTA

Wenting Li,Yongqiang Shi,Yuanyuan Zhu,Yongjian Yu,Dong Han,Xiaobo Zou,Jiyong Shi

This study developed a novel dual-functional portable electrochemical biosensor capable of simultaneous and sensitive detection of AFB 1 and OTA. The biosensor incorporates SPCE modified with gold nanoflowers, which not only enhances electrical conductivity and specific surface area of work electrode but also supports the stable immobilization of DNA tetrahedral probes. This biosensor utilizes ferrocene and methylene blue as distinct electrochemical signal reporters and enables specific and parallel recognition of AFB 1 and OTA in a single measurement, this strategy greatly improves its detection efficiency. Integrated with a portable electrochemical workstation and smartphone, this platform facilitates rapid, user-friendly, and real-time mycotoxin detection. Under optimized conditions, the biosensor exhibited wide linear detection ranges (0.05–250 ng/mL) and impressive detection limits of 2.8 pg/mL (AFB 1 ) for and 4.1 pg/mL (OTA). This work developed platform exhibits excellent stability and field applicability, providing a practical integrated solution for on-site screening of multiple mycotoxin in agricultural products.

Development and application of the physiologically-based toxicokinetic (PBTK) model for ochratoxin A (OTA) in rats and humans

Bu-Da Su,Xiao-Meng Li,Zhi-Wei Huang,Yue Wang,Jia Shao,Yan-Yan Xu,Le-Xin Shu,Yu-Bo Li

Ochratoxin A (OTA) is a common fungal toxin frequently detected in food and human plasma samples. Currently, the physiologically based toxicokinetic (PBTK) model plays an active role in dose translation and can improve and enhance the risk assessment of toxins. In this study, the PBTK model of OTA in rats and humans was established based on knowledge of OTA-specific absorption, distribution, metabolism, and excretion (ADME) in order to better explain the disposition of OTA in humans and the discrepancies with other species. The models were calibrated and optimized using the available kinetic and toxicokinetic (TK) data, and independent test datasets were used for model evaluation. Subsequently, sensitivity analyses and population simulations were performed to characterize the extent to which variations in physiological and specific chemical parameters affected the model output. Finally, the constructed models were used for dose extrapolation of OTA, including the rat-to-human dose adjustment factor (DAF) and the human exposure conversion factor (ECF). The results showed that the unbound fraction (F up ) of OTA in plasma of rat and human was 0.02–0.04% and 0.13–4.21%, respectively. In vitro experiments, the maximum enzyme velocity (V max ) and Michaelis–Menten constant (K m ) of OTA in rat and human liver microsomes were 3.86 and 78.17 μg/g min −1 , 0.46 and 4.108 μg/mL, respectively. The predicted results of the model were in good agreement with the observed data, and the models in rats and humans were verified. The PBTK model derived a DAF of 0.1081 between rats and humans, whereas the ECF was 2.03. The established PBTK model can be used to estimate short- or long-term OTA exposure levels in rats and humans, with the capacity for dose translation of OTA to provide the underlying data for risk assessment of OTA.

On-site detection of OTA and AFB1 based on branched hybridization chain reaction coupled with lateral flow assay

Wenjun Jiang,Yidan Zhu,Qu Tang,Xiaoxia Kang,Haiwei Ji,Conglin Guo,Xijuan Gu,Jing Zhang,Zhenzhen Mao,Li Wu,Yuling Qin

Mycotoxins are widely prevalent in various agricultural commodities, whose excessive consumption can pose significant risks to human health. In this study, we developed a facile mycotoxin detection platform based on branched hybridization chain reaction coupled with lateral flow assay. Ochratoxin A/Aflatoxin B1 bind to aptamers triggering the release of initiators, which leads to bHCR amplification and forms three-dimensional dendritic DNA nanostructures. Using the functionalized quantum dots as a fluorescent label, by leveraging smartphones and handheld ultraviolet lamps, the qualitative and quantitative detection of OTA and AFB1 can be achieved with a significantly enhanced sensitivity level, surpassing that of commercial test strips by 2–3 orders of magnitude. The visual detection limits for OTA and AFB1 were 30 pg/mL and 4 pg/mL, respectively. This approach eliminates the necessity for enzyme catalysis or the preparation and purification of antibodies and/or hapten, thereby reducing testing expenses and streamlining operational procedures. Moreover, substituting aptamer and nucleic acid sequences can effectively expand the scope of detection targets. Consequently, the as-proposed strategy exhibits great potential as a versatile technique, suitable for various analytical scenarios due to its sensitivity, accuracy, simplicity, and portability.

A novel ratiometric aptasensor based on dual-emission fluorescent signals and the conformation of G-quadruplex for OTA detection

Hualin Guo,Pengfei Ma,Ke Li,Shuxia Zhang,Yin Zhang,Huiqing Guo,Zhouping Wang

Ochratoxin A (OTA) is known as an important mycotoxin that is widely distributed in food products. The increasing requirement for sensitive and convenient OTA detection has promoted the development of aptasensors based on nanomaterials and elegant design strategy for aptamer probes. Ratiometric fluorescence aptasensors greatly reduce the probability of generating false-positive signals, compared to one-signal detection methods. In this work, an efficient ratiometric aptasensor was constructed, based on the dual-emission fluorescence of N -methyl mesoporphyrin IX (NMM) and copper nanoclusters (CuNCs). The key binding region of aptamer was obtained by theoretical results of molecular docking, and experiments of optimizing the length of complementary DNA (cDNA) verified the conjecture. With the addition of OTA, CuNCs-cDNA dissociated from the aptamer sequence, and the fluorescence of CuNCs (λ em =510 nm) decreased. Meanwhile, the aptamer contained G-quadruplex structure and enhanced the fluorescence of NMM (λ em =610 nm). In this way, fluorescence intensity at the emission wavelength of 610 nm and 510 nm were monitored and I 610 /I 510 was set as the signal output of this aptasensor. Stability tests indicated that the established aptasensor can reduce the interference of pH and storage time. The limit of detection (LOD) was as low as 0.045 ng/mL, with a wide linear range of 0.05–100 ng/mL. Moreover, specificity tests provided excellent selectivity towards other common mycotoxins, and the applicability was confirmed by performing real sample analysis, indicating that the NMM/CuNCs ratiometric biosensor for OTA detection has practical application prospects in food samples.

A label-free fluorescence sensor for OTA detection based on enzymatic recycling -mediated precise regulation of DNA-templated silver nanocluster

Yan Yang,Wenxin Mai,Shuojie Wang,Guixiang Teng,Shiyu Wei,Meiling Shi,Yongqiang Tian

Ochratoxin A (OTA) is a widespread mycotoxin in food chains, yet conventional aptamer-based assays remain challenging because of the background signals and matrix interference. Here, we introduced a target-triggered reporter synthesis mechanism in which OTA binding unlocks a TdT- Nt.AlwI enzymatic cycle that generates polyT strands exclusively in the presence of the target. These generated polyT products interact specifically with polyA-recognition motifs on DNA-templated silver nanoclusters (DNA-AgNCs), enabling fluorescence transduction for OTA detection. This “zero-to-one” generative logic gate ensures that signal molecules are produced exclusively after recognition, intrinsically suppressing blank background. Moreover, the enzymatic cycle allows a single OTA molecule to trigger the generation of multiple polyT strands, imparting signal amplification without external labels or immobilization. Furthermore, integrating target-initiated nucleic acid synthesis with orthogonal optical transduction enables the construction of a label-free assay that intrinsically decreases background noise from signal generation, thereby ensuring high specificity, low interference, and quantitative reliability for target detection. The assay shows a linear response from 10 pM to 50 nM, achieves a detection limit of 0.097 ng mL −1 , and yields 86.4–94.1 % recoveries with<8.1 % RSD in spiked soybean extracts. By suppressing baseline noise at the mechanism level and separating amplification from readout, this platform enables sensitive, low false-positive OTA quantification and is readily adaptable to other small molecules by exchanging the aptamer, advancing portable food-safety screening.

Simultaneous detection of OTA and AFB1 in cereals based on bispecific monoclonal antibody using quantum dot nanobead lateral flow immunoassay

Mengyun Wu,Jun Xia,Tingting Liu,Guangjian Xue,Xuechen Fang,Weihua Lai,Juan Peng

A self-calibrated electrochemical aptasensor based on DNA-mediated Au/PB NFs and Pt/ZnCo MOF for the detection of OTA

Yin Yanjun,Shen Hailin,Wang Mengyao,Suo Zhiguang,Liu Yong,Wei Min

A self-calibrated ratiometric electrochemical aptasensor was developed for the detection of ochratoxin A. This sensor is based on DNA-mediated gold/prussian blue nanoflowers (Au/PB NFs), methylene blue/platinum/zinc-cobalt metal-organic framework (MB/Pt/ZnCo MOF), and an exonuclease III (Exo III)–driven bipedal DNA walker cyclic amplification strategy. The self-calibration mechanism of this sensor relies on the ratio between the response signal of MB/Pt/ZnCo MOF (I MB ) and the internal reference signal of Au/PB NFs (I PB ). This ratio can effectively resist external interference factors. DNA-mediated Au/PB NFs with a flower-like structure provide stable internal reference signals and promote electron transfer. MB/Pt/ZnCo MOF, leveraging ZnCo MOF with a porous structure and bimetallic synergistic effects, and Pt with electrocatalytic activity, serve as response signals. An Exo III–driven biped DNA walker was used to realize the cyclic amplification strategy. The sensor showed a wide linear range of 0.001~500 ng/mL, with a low limit of detection of 0.17 pg/mL. The detection capability of spiked corn flour, wine, and coffee powder samples was satisfactory, and the detection results for the quality control samples of coarse rice flour and wheat flour were not significantly different from those of high-performance liquid chromatography (HPLC), showing the potential for practical application.

An Extremely Highly Sensitive ELISA in pg mL−1 Level Based on a Newly Produced Monoclonal Antibody for the Detection of Ochratoxin A in Food Samples

Yexuan Ren,Ruwen Tian,Ting Wang,Junlin Cao,Jianguo Li,Anping Deng

In this study, an extremely highly sensitive enzyme-linked immunosorbent assay (ELISA) based on a newly produced monoclonal antibody (mAb) for the detection of ochratoxin A (OTA) in food samples was developed. OTA-Bovine serum albumin (BSA) conjugate was prepared and used as the immunogen for the production of the mAb. Among four hybridoma clones (8B10, 5C2, 9B7, and 5E11), the antibody from 8B10 displayed the highest affinity recognition for OTA. Based on the mAb (8B10), the IC50and LOD of the ELISA for OTA were 34.8 pg mL−1and 1.5 pg mL−1, respectively, which was 1.53~147 times lower than those in published ELISAs, indicating the ultra-sensitivity of our assay. There was no cross-reactivity of the mAb with the other four mycotoxins (AFB1, ZEN, DON, and T-2). Due to the high similarity in molecular structures among OTA, ochratoxin B (OTB), and ochratoxin C (OTC), the CR values of the mAb with OTB and OTC were 96.67% and 22.02%, respectively. Taking this advantage, the ELISA may be able to evaluate total ochratoxin levels in food samples. The recoveries of the ELISA for OTA in spiked samples (corn, wheat, and feed) were 96.5–110.8%, 89.5–94.4%, and 91.8–113.3%; and the RSDs were 5.2–13.6%, 8.2–13.0%, and 7.7–13.7% (n= 3), respectively. The spiked food samples (corn) were measured by ELISA and HPLC-FLD simultaneously. A good correlation between ELISA (x) and HPLC-FLD (y) with the linear regression equation of y = 0.918x − 0.034 (R2= 0.985,n= 5) was obtained. These results demonstrated that the newly produced mAb-based ELISA was a feasible and ultra-sensitive analytical method for the detection of OTA in food samples.Keywords:enzyme-linked immunosorbent assay (ELISA);monoclonal antibody (mAb);mycotoxin;ochratoxin A (OTA);food samples;sensitive detection

Highly hydrophilic polyhedral oligomeric silsesquioxane (POSS)-containing aptamer-modified affinity hybrid monolith for efficient on-column discrimination with low nonspecific adsorption

Yiqiong Chen,Dandan Zhu,Xinyue Ding,Guomin Qi,Xucong Lin,Zenghong Xie

A novel polyhedral oligomeric silsesquioxane (POSS)-containing aptamer-modified hybrid affinity monolith with excellent hydrophilicity and unique architecture without Si–OH groups is presented herein, and the nonspecific adsorption caused by the hydrophobic nature of the monolithic column or polar interaction with silanol groups is minimized. Via a simple “one-pot” procedure, hydrophilic monomers were facilely polymerized with the POSS-methacryl substituted (POSS-MA) and aptamer; a highly hydrophilic nature was obtained and the lowest contact angle of 11° was achieved. By using ochratoxin A (OTA) as the model analyte, highly selective recognition of OTA in the mixture was achieved and the control of nonspecific interactions and the cross-reactivity of OTB and AFB1 were significantly improved. The recovery yield of OTB caused by nonspecific adsorption in the resultant monolith was only about 0.1% and remained steady even with the coexistence of a high OTB content (OTA : OTB = 1 : 50), which reached the best level to date and was obviously less than the 6.1% occurring in the hydrophobic POSS-containing control monolith, 8.3% in the POSS-PEI@AuNPs@aptamer affinity monolith and 18.7% in the silica-hybrid affinity monolith. When applied to wine and wheat samples, the nonspecific adsorption was significantly reduced and efficient discrimination of OTA was obtained with better results than that of the hydrophobic POSS-containing affinity column. This provides an attractive tool for minimizing the nonspecific adsorption for highly selective on-column recognition.