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Published: 1 September 2022
by MDPI
Journal: Micromachines
Micromachines, Volume 13; https://doi.org/10.3390/mi13091441

Abstract:
Aptamers are important materials for the specific determination of different disease-related biomarkers. Several methods have been enhanced to transform selected target molecule-specific aptamer bindings into measurable signals. A number of specific aptamer-based biosensors have been designed for potential applications in clinical diagnostics. Various methods in combination with a wide variety of nano-scale materials have been employed to develop aptamer-based biosensors to further increase sensitivity and detection limit for related target molecules. In this critical review, we highlight the advantages of aptamers as biorecognition elements in biosensors for target biomolecules. In recent years, it has been demonstrated that electrode material plays an important role in obtaining quick, label-free, simple, stable, and sensitive detection in biological analysis using piezoelectric devices. For this reason, we review the recent progress in growth of aptamer-based QCM biosensors for medical diagnoses, including virus, bacteria, cell, protein, and disease biomarker detection.
Published: 26 August 2022
by MDPI
Journal: Molecules
Abstract:
Low-density lipoprotein (LDL) is a cardiac biomarker identified in the pathology of cardiovascular disease (CVD). Typically, the level of LDL is calculated using the Friedewald relationship based on measured values of total cholesterol, high-density lipoproteins (HDL), and triglycerides. Unfortunately, this approach leads to some errors in calculation. Therefore, direct methods that can be used for fast and accurate detection of LDL are needed. The purpose of this study was to develop an electrochemical platform for the detection of LDL based on an antibody–ferrocene conjugate. An anti-apolipoprotein B-100 antibody labeled with ferrocene was covalently immobilized on the layer of 4-aminothiophenol (4-ATP) on the surface of gold electrodes. Upon interaction between LDL and the antibody–ferrocene conjugate, a decrease in the ferrocene redox signal registered by square wave voltammetry was observed, which depends linearly on the concentration from 0.01 ng/mL to 1.0 ng/mL. The obtained limit of detection was equal to 0.53 ng/mL. Moreover, the satisfied selectivity toward human serum albumin (HSA), HDL, and malondialdehyde-modified low-density lipoprotein (MDA-LDL) was observed. In addition, the acceptable recovery rates of LDL in human serum samples indicate the possible application of immunosensors presented in clinical diagnostics.
Published: 27 April 2022
by MDPI
Journal: Toxins
Abstract:
Aflatoxin, a type of mycotoxin, is mostly produced by Aspergillus flavus and Aspergillus parasiticus. It is responsible for the loss of billions of dollars to the world economy, by contaminating different crops such as cotton, groundnut, maize, and chilies, and causing immense effects on the health of humans and animals. More than eighteen different types of aflatoxins have been reported to date, and among them, aflatoxins B1, B2, G1, and G2 are the most prevalent and lethal. Early detection of fungal infection plays a key role in the control of aflatoxin contamination. Therefore, different methods, including culture, chromatographic techniques, and molecular assays, are used to determine aflatoxin contamination in crops and food products. Many countries have set a maximum limit of aflatoxin contamination (2–20 ppb) in their food and agriculture commodities for human or animal consumption, and the use of different methods to combat this menace is essential. Fungal infection mostly takes place during the pre- and post-harvest stage of crops, and most of the methods to control aflatoxin are employed for the latter phase. Studies have shown that if correct measures are adopted during the crop development phase, aflatoxin contamination can be reduced by a significant level. Currently, the use of bio-pesticides is the intervention employed in many countries, whereby atoxigenic strains competitively reduce the burden of toxigenic strains in the field, thereby helping to mitigate this problem. This updated review on aflatoxins sheds light on the sources of contamination, and the on occurrence, impact, detection techniques, and management strategies, with a special emphasis on bio-pesticides to control aflatoxins.
Published: 20 November 2021
by MDPI
Journal: Sensors
Sensors, Volume 21; https://doi.org/10.3390/s21227733

Abstract:
An elevated level of low density lipoprotein (LDL) can lead to the cardiovascular system-related diseases, such as atherosclerosis and others. Therefore, fast, simple, and accurate methods for LDL detection are very desirable. In this work, the parameters characterizing the electrochemical immuno-and aptasensor for detection of LDL have been compared for the first time. An immunosensor has been designed, for which the anti-apolipoprotein B-100 antibody was covalently attached to 4-aminothiophenol (4-ATP) on the surface of the gold electrode. In the case of an aptasensor, the gold electrode was modified in a mixture of ssDNA aptamer specific for LDL modified with –SH group and 6-mercaptohexanol. Square-wave voltammetry has been used for detection of LDL in PBS containing redox active marker, [Fe(CN)6]3−/4−. Our results show the linear dependence of [Fe(CN)6]3−/4− redox signal changes on LDL concentration for both biosensors, in the range from 0.01 ng/mL to 1.0 ng/mL. The limit of detection was 0.31 and 0.25 ng/mL, for immuno- and aptasensor, respectively. Whereas slightly better selectivity toward human serum albumin (HSA), high density lipoprotein (HDL), and malondialdehyde modified low density lipoprotein (MDA-LDL) has been observed for aptasensor. Moreover, the other components of human blood serum samples did not influence aptasensor sensitivity.
Melvin S. Samuel, K. Mohanraj, , Ramachandran Balaji,
Published: 27 October 2021
Journal: Chemosphere
The publisher has not yet granted permission to display this abstract.
Published: 17 July 2021
by MDPI
Journal: Toxins
Abstract:
Mycotoxin contamination of cereals used for feed can cause intoxication, especially in farm animals; therefore, efficient analytical tools for the qualitative and quantitative analysis of toxic fungal metabolites in feed are required. Current trends in food/feed analysis are focusing on the application of biosensor technologies that offer fast and highly selective and sensitive detection with minimal sample treatment and reagents required. The article presents an overview of the recent progress of the development of biosensors for deoxynivalenol and zearalenone determination in cereals and feed. Novel biosensitive materials and highly sensitive detection methods applied for the sensors and the application of these sensors to food/feed products, the limit, and the time of detection are discussed.
M. Dwiki Destian Susilo, Teguh Jayadi, Ahmad Kusumaatmaja, Ari Dwi Nugraheni
Published: 1 March 2021
Materials Science Forum, Volume 1023, pp 103-109; https://doi.org/10.4028/www.scientific.net/msf.1023.103

Abstract:
Aflatoxin B1 (AFB1) is one of the mycotoxins with the most dangerous poisons and poses a threat to living things. Several detection methods for Aflatoxin B1 (AFB1) with high sensitivity (LC-MS technique, HPLC, ELISA, etc.) still require lengthy preparation time and are not real-time and portable. Aflatoxin B1 (AFB1) detection is one of the major challenges in the field of food safety because Aflatoxin B1 (AFB1) attacks the food and agricultural products sector. One of the potential sensors that can be used as a base for Aflatoxin B1 (AFB1) detection is the Quartz Crystal Microbalance (QCM) sensor. This study examines the performance of the Quartz Crystal Microbalance (QCM) sensor as one of the Aflatoxin B1 detection techniques through the physical deposition method. The Quartz Crystal Microbalance (QCM) sensor modified uses polyvinyl acetate (PVAc) material as a container to embed a molecular model that will be detected through a molecular imprinting polymer (MIP) process coated on QCM using the electrospinning method. The response results show that the value of the sensor response using the MIP process is more significant than without the MIP process. The sensor characteristics demonstrated by the PVAc/AFB 50 sample have a limit of detection (LOD) value is 0.63 ppb, and a limit of quantitation (LOQ) is 1.91 ppb with a coefficient correlation is 0.97 for testing with a concentration range of 5.0 – 40.0 ppb. Therefore, the MIP process in QCM provides a favorable response for the detection of AFB1 in the future.
Published: 5 February 2021
by MDPI
Journal: Sensors
Sensors, Volume 21; https://doi.org/10.3390/s21041118

Abstract:
In this paper, a polyimide (PI)/Si/SiO2-based piezoresistive microcantilever biosensor was developed to achieve a trace level detection for aflatoxin B1. To take advantage of both the high piezoresistance coefficient of single-crystal silicon and the small spring constant of PI, the flexible piezoresistive microcantilever was designed using the buried oxide (BOX) layer of a silicon-on-insulator (SOI) wafer as a bottom passivation layer, the topmost single-crystal silicon layer as a piezoresistor layer, and a thin PI film as a top passivation layer. To obtain higher sensitivity and output voltage stability, four identical piezoresistors, two of which were located in the substrate and two integrated in the microcantilevers, were composed of a quarter-bridge configuration wheatstone bridge. The fabricated PI/Si/SiO2 microcantilever showed good mechanical properties with a spring constant of 21.31 nN/μm and a deflection sensitivity of 3.54 × 10−7 nm−1. The microcantilever biosensor also showed a stable voltage output in the Phosphate Buffered Saline (PBS) buffer with a fluctuation less than 1 μV @ 3 V. By functionalizing anti-aflatoxin B1 on the sensing piezoresistive microcantilever with a biotin avidin system (BAS), a linear aflatoxin B1 detection concentration resulting from 1 ng/mL to 100 ng/mL was obtained, and the toxic molecule detection also showed good specificity. The experimental results indicate that the PI/Si/SiO2 flexible piezoresistive microcantilever biosensor has excellent abilities in trace-level and specific detections of aflatoxin B1 and other biomolecules.
Published: 16 December 2020
Food and Chemical Toxicology, Volume 148; https://doi.org/10.1016/j.fct.2020.111931

Abstract:
This work focuses on the study of nanomaterial-based sensors for mycotoxins detection. Due to their adverse effects on humans and animals, mycotoxins are heavily regulated, and the foodstuff and feed stocks with a high probability of being contaminated are often analyzed. In this context, the recent developments in graphene-based electrochemical sensors for mycotoxins detection were examined. The mycotoxins' toxicity implications on their detection and the development of diverse recognition elements are described considering the current challenges and limitations.
Published: 30 November 2020
by MDPI
Journal: Chemosensors
Abstract:
Aflatoxins are highly toxic fungal secondary metabolites that often contaminate food and feed commodities. An electrochemical immunosensor for the determination of aflatoxin B1 (AFB1) was fabricated by immobilizing monoclonal AFB1 antibodies onto a screen-printed gold electrode that was modified with carbo-methyldextran by N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide cross-linking. An electrochemical interfacial modelling of biomolecular recognition was suggested and reasonably interpreted. Impedance technology was employed for the quantitative determination of AFB1. The limit of detection concentration of AFB1 for standard solutions and spiked pistachio samples was 0.5 ng/mL and 1 ng/mL, respectively. The immunosensor was able to successfully determine AFB1 concentrations in the range of 4.56–50.86 ng/mL in unknown pistachio samples. Comparative chromatographic analysis revealed that AFB1 concentrations that were higher than 345 ng/mL were not within the immunosensor’s upper limits of detection. Selectivity studies against Ochratoxin A and Aflatoxin M1 demonstrated that the proposed AFB1 immunosensor was able to differentiate between these other fungal mycotoxins. The novel electrochemical immunosensor approach has the potential for rapid sample screening in a portable, disposable format, thus contributing to the requirement for effective prevention and the control of aflatoxin B1 in pistachios.
Ismail I. Althagafi, ,
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 246; https://doi.org/10.1016/j.saa.2020.118999

The publisher has not yet granted permission to display this abstract.
Hui Jean Lim, Tridib Saha, Beng Ti Tey, Wen Siang Tan,
Published: 23 August 2020
Biosensors and Bioelectronics, Volume 168, pp 112513-112513; https://doi.org/10.1016/j.bios.2020.112513

Abstract:
Infectious diseases are the ever-present threats to public health and the global economy. Accurate and timely diagnosis is crucial to impede the progression of a disease and break the chain of transmission. Conventional diagnostic techniques are typically time-consuming and costly, making them inefficient for early diagnosis of infections and inconvenient for use at the point of care. Developments of sensitive, rapid, and affordable diagnostic methods are necessary to improve the clinical management of infectious diseases. Quartz crystal microbalance (QCM) systems have emerged as a robust biosensing platform due to their label-free mechanism, which allows the detection and quantification of a wide range of biomolecules. The high sensitivity and short detection time offered by QCM-based biosensors are attractive for the early detection of infections and the routine monitoring of disease progression. Herein, the strategies employed in QCM-based biosensors for the detection of infectious diseases are extensively reviewed, with a focus on prevalent diseases for which improved diagnostic techniques are in high demand. The challenges to the clinical application of QCM-based biosensors are highlighted, along with an outline of the future scope of research in QCM-based diagnostics.
Chansi, Rashi Bhardwaj, R. Pragadeeshwara Rao, Irani Mukherjee, Pawan Kumar Agrawal, , Lalit M. Bharadwaj
Published: 26 June 2020
Journal of Electroanalytical Chemistry, Volume 873; https://doi.org/10.1016/j.jelechem.2020.114386

The publisher has not yet granted permission to display this abstract.
Lourdes Cervera-Chiner, Yolanda Jiménez, Ángel Montoya, Marisol Juan-Borrás, Nuria Pascual, Antonio Arnau,
Published: 10 April 2020
Journal: Food Control
The publisher has not yet granted permission to display this abstract.
Qi Wang, Qingli Yang, Wei Wu
Published: 27 March 2020
Frontiers in Microbiology, Volume 11; https://doi.org/10.3389/fmicb.2020.00408

Abstract:
Aspergillus exists commonly in many crops and any process of crop growth, harvest, storage, and processing can be polluted by this fungus. Once it forms a biofilm, Aspergillus can produce many toxins, such as aflatoxin B1 (AFB1), ochratoxin, zearalenone, fumonisin, and patulin. Among these toxins, AFB1 possesses the highest toxicity and is labeled as a group I carcinogen in humans and animals. Consequently, the proper control of AFB1 produced from biofilms in food and feed has long been recognized. Moreover, many biosensors have been applied to monitor AFB1 in biofilms in food. Additionally, in recent years, novel molecular recognition elements and transducer elements have been introduced for the detection of AFB1. This review presents an outline of recent progress made in the development of biosensors capable of determining AFB1 in biofilms, such as aptasensors, immunosensors, and molecularly imprinted polymer (MIP) biosensors. In addition, the current feasibility, shortcomings, and future challenges of AFB1 determination and analysis are addressed.
Jyoti Singh,
Published: 25 March 2020
Food Science & Nutrition, Volume 8, pp 2183-2204; https://doi.org/10.1002/fsn3.1474

The publisher has not yet granted permission to display this abstract.
Muhammad Rizwan Younis, , Xing‐Hua Xia
Published: 14 February 2020
The publisher has not yet granted permission to display this abstract.
Frank Daliri, Agnes Achiaa Aboagye, Vincent Kyei-Baffour, Fazle Elahi, Ramachandran Chelliah, Eric Banan-Mwine Daliri
Journal of Food Hygiene and Safety, Volume 34, pp 509-518; https://doi.org/10.13103/jfhs.2019.34.6.509

, Xian-He Huang, Wei Pan, Yao Yao
Published: 1 December 2019
Chinese Physics Letters, Volume 36; https://doi.org/10.1088/0256-307x/36/12/120702

Abstract:
A high-Q quartz crystal microbalance (QCM) sensor with a fundamental resonance frequency of 210 MHz is developed based on inverted mesa technology. The mass sensitivity reaches 5.332 × 1017Hz/kg at the center of the electrode, which is 5–7 orders of magnitude higher than the commonly used 5 MHz or 10 MHz QCMs (their mass sensitivity is 1010–1012Hz/kg). This mass sensitivity is confirmed by an experiment of plating 1-ng rigid aluminium films on the surface of the QCM sensor. By comparing the changes in QCM equivalent parameters before and after coating the aluminum films, it is found that the QCM sensor maintains the high-Q characteristics of the quartz crystal while the mass sensitivity is significantly improved. Therefore, this QCM sensor may be used as a promising analytical tool for applications requiring high sensitivity detection.
Somayeh Mousavi Nodoushan, , Reza Kachuei, Abbas Ali Imani Fooladi
Published: 30 October 2019
Analytical Methods, Volume 11, pp 6033-6042; https://doi.org/10.1039/c9ay01673b

Abstract:
An electrochemical aptasensor was developed for the detection of aflatoxin B1 using a nanocomposite of graphene oxide and gold nanowires.
Published: 14 September 2019
by MDPI
Journal: Sensors
Sensors, Volume 19; https://doi.org/10.3390/s19183968

Abstract:
Mass sensitivity is vital for quartz crystal microbalance (QCM)-based data analysis. The mass sensitivity distribution of QCMs may differ greatly depending on the shapes, thicknesses, sizes, and materials of the metal electrodes. This is not considered by the Sauerbrey equation, and has a large potential to cause errors in QCM-based data analysis. Many previous works have studied the effects of shape, thickness, and size of metal electrodes on mass sensitivity. However, it is necessary to continue to clarify the relationship between the mass sensitivity and the electrode material of the QCM. In this paper, the results of both theoretical calculation and experimental analysis showed that the mass sensitivity of QCMs with gold electrodes is higher than that of the QCMs with silver electrodes, which in turn indicated that the mass sensitivity of QCMs varies with the electrode material. Meanwhile, the results of this study showed that the mass sensitivity of QCMs with different electrode materials is not proportional to the density of the electrode materials. This result suggests that, in order to obtain more accurate results in the practical applications of QCMs, the influence of electrode material on the mass sensitivity of the QCMs must be considered.
Tao Wei, Pingping Ren, Linli Huang, Zicheng Ouyang, Ziying Wang, Xiangfeng Kong, Tiejun Li, Yulong Yin, ,
Published: 13 July 2019
Journal: Food chemistry
Abstract:
Mycotoxins are toxic metabolites produced by fungi or molds, which may cause serious harm to human health through polluted cereal foods. In order to measure the typical mycotoxin contaminations in wheat and corn, a surface plasmon resonance (SPR) method was established using SPR sensor chip that was fabricated based on self-assembled monolayer. The minimum detection limit of aflatoxin B1, ochratoxin A, zearalenone and deoxynivalenol were identified as 0.59 ng/mL, 1.27 ng/mL, 7.07 ng/mL and 3.26 ng/mL, respectively. The cross-reactivity for all four mycotoxins were demonstrated to be low. Moreover, the test data were compared with HPLC-MS/MS confirmatory analysis results and good agreement was found between them. In conclusion, the SPR method for simultaneously detecting four mycotoxins has been developed with high sensitivity, good linearity and specificity, which can meet the detection requirements of cereal foods.
Yaguang Yun, , Lulu Wang, Shijie Li, Yanan Wang, Ying Gu, Jingying Yang,
Published: 26 June 2019
Analytical and Bioanalytical Chemistry, Volume 411, pp 5745-5753; https://doi.org/10.1007/s00216-019-01954-4

Abstract:
A label-free piezoelectric immunosensor was fabricated and applied to the detection of the antiviral drug amantadine (AM) in foods of animal origin. Experimental parameters associated with the fabrication and measurement process were optimized and are discussed here in detail. The proposed piezoelectric sensor is based on an immunosuppression format and uses a portable quartz crystal microbalance (QCM) chip. It was found to provide a good response to AM, with a sensitivity and limit of detection (LOD) of 33.9 and 1.3 ng mL−1, respectively, as well as low cross-reactivity (CR, < 0.01%) with AM analogues. The immunosensor was further applied to quantify AM at three levels in spiked samples of typical foods of animal origin, and yielded recoveries of 83.2–93.4% and standard deviations (SDs, n = 3) of 2.4–4.5%, which are comparable to the results (recoveries: 82.6–94.3%; SDs: 1.7–4.2%) obtained using a high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS) method. Furthermore, the piezoelectric immunosensing chip can be regenerated multiple (at least 20) times with low signal attenuation (about 10%). A sample analysis can be completed within 50 min (sample pretreatment: about 40 min, QCM measurement: 5 min). These results demonstrate that the developed piezoelectric immunosensor provides a sensitive, accurate, portable, and low-cost analytical strategy for the antiviral drug AM in foods of animal origin, and this label-free detection method could also be applied to analyze other targets in the field of food safety. Graphical abstract
Yuan Tian, Yang Wang, Xiaomei Yu
Abstract:
In this work, we propose an ultrasensitive detection of aflatoxin B1 using a piezoresistive microcantilever biosensor, which is composed of doped piezoresistive layer, top polyimide (PI) passive layer and bottom silicon oxide (SiO 2 ) passive layer. Four microcantilevers with the same dimensions consist of a wheatstone bridge to achieve a higher sensitivity and better noise performance. The fabricated PI/Si/SiO 2 microcantilever shows a steady output with less than 1 μ[email protected] fluctuation in PBS buffer, while the spring constant is 21.307 nN/μm and the deflection sensitivity is 3.54×10 -7 nm -1 . Detections on aflatoxin B1 with a minimum concentration of 1 ng/mL were achieved.
Ismail I. AlThagafi, Saleh A. Ahmed,
Published: 16 January 2019
Journal: PLoS ONE
Abstract:
Aflatoxins (AFs) are a family of fungal toxins that produced in food and feed by two Aspergillus species (Aspergillus flavus and Aspergillus parasiticus). Several techniques have been reported for AFs detection including high-pressure liquid chromatography, enzyme-linked immunosorbent assay, surface plasmon resonance and recombinant immune blotting assay. But, these methods are disadvantaged because they consumed a long time for analysis; in addition, they required a piece of complicated and expensive equipment. Therefore, developing of inexpensive sensors with high selectivity and sensitivity for detecting of AFs levels without extensive sample preparation has received great attention. Several electrochemical AFs sensors have been reported; however, there is still a need for developing a new, simple and rapid electrochemical AFs sensor. Here, we have developed a new AFs sensor based on Au nanostructures/graphene nanosheets modified ITO substrate that could enhance the Raman effect and the electrochemical conductivity. The modified electrode was prepared based on layer-by-layer electrochemical deposition method. AFs antibody was immobilized onto the Au nanostructures/graphene nanosheets; then it was used as a probe for rapid, simple and cheap detection of AFs level using Raman spectroscopy and electrochemical techniques. Our results demonstrated that the developed system showed a simple, easy and sensitive sensor for monitoring low concentrations of AFB1 with a detection limit of about 6.9 pg/mL, also it allowed the determination of AFB1 in spiked food samples.
Ying Tang, , Jin Zhang,
Published: 1 November 2018
Analytica chimica acta, Volume 1031, pp 161-168; https://doi.org/10.1016/j.aca.2018.05.027

Abstract:
A simple and sensitive quartz crystal microbalance (QCM) immunosensing platform was designed for the high-efficient detection of aflatoxin B1 (AFB1) in foodstuff. Initially, phenoxy-derived dextran molecule was immobilized on the surface of QCM gold substrate by using thiolated β-cyclodextrin based on the supramolecular host-guest chemistry between phenoxy group and cyclodextrin. Then, AFB1-bovine serum albumin (AFB1-BSA)-conjugated concanavalin A (Con A) was assembled onto the QCM probe through the dextran-Con A interaction. Glucose-loaded nanoliposome, labeled with monocolonal anti-AFB1 antibody, was used for the amplification of QCM signal. Upon target AFB1 introduction, the analyte competed with the immobilized AFB1-BSA on the probe for the labeled anti-AFB1 antibody on the nanoliposome. Based on specific antigen-antibody reaction, the amount of the conjugated nanoliposomes on the QCM probe gradually decreased with the increment of target AFB1 in the sample. Upon injection of Triton X-100 in the detection cell, the carried nanoliposome was lysed to release the encapsulated glucose molecules. Thanks to the stronger affinity of Con A toward glucose than that of dextran, AFB1-BSA-labeled Con A was displaced from the QCM probe, resulting in the change of the local frequency. Under the optimum conditions, the shift of the functionalized QCM immunosensing interface in the frequency shift was proportional to the concentration of target AFB1 within a dynamic range from 1.0 ng kg−1 to 10 μg kg-1 at a low detection limit of 0.83 ng kg−1. In addition, the acceptable assayed results on precision, reproducibility, specificity and method accuracy for the analysis of real samples were also acquired. Importantly, our strategy can provide a signal-on competitive immunoassay for the detection of small molecules, e.g., mycotoxins and biotoxins, thereby representing a versatile sensing schemes by controlling the corresponding antibody or hapten in the analysis of food safety.
K. Yugender Goud, , , , S.E. Lee, K. Vengatajalabathy Gobi,
Published: 16 August 2018
Biosensors and Bioelectronics, Volume 121, pp 205-222; https://doi.org/10.1016/j.bios.2018.08.029

Abstract:
Nanomaterial-embedded sensors have been developed and applied to monitor various targets. Mycotoxins are fungal secondary metabolites that can exert carcinogenic, mutagenic, teratogenic, immunotoxic, and estrogenic effects on humans and animals. Consequently, the need for the proper regulation on foodstuff and feed materials has been recognized from times long past. This review provides an overview of recent developments in electrochemical sensors and biosensors employed for the detection of mycotoxins. Basic aspects of the toxicity of mycotoxins and the implications of their detection are comprehensively discussed. Furthermore, the development of different molecular recognition elements and nanomaterials required for the detection of mycotoxins (such as portable biosensing systems for point-of-care analysis) is described. The current capabilities, limitations, and future challenges in mycotoxin detection and analysis are also addressed.
, Hongbo Wang, , Zhenguo Ji
Published: 1 June 2018
Materials Research Express, Volume 5; https://doi.org/10.1088/2053-1591/aaca0d

Abstract:
The detection of aflatoxin B1 (AFB1) using immunoassays, especially electrochemical immunoassays, is fast, sensitive and efficient. In this study, 2-aminoethanethiol was used to enhance the speed and sensitivity of conventional electrochemical immunoassays for AFB1 detection by assembly on the surface of a Au electrode, forming self-assembled monolayers (SAMs). Then, non-competitive immunoassays occurred on the modified electrode surface forming an electrochemical immunoassay sensor. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy were used to examine the state of the SAMs, and an electrochemical workstation was used to monitor the current change of the electrochemical reaction, so as to characterize the designed immunosensor. Our experimental results shows that, the 2-aminoethanethiol reagent was successfully assembled on the Au surface through Au-S bonding and the –NH2 terminal group faced outward. Herein, the minimum concentration of AFB1 which caused a significant current change was 0.01 ng/mL. The prepared immunosensor also exhibited excellent stability and sensitivity after storage for 7 days or upon regeneration.
Wenbo Wu, Zhiling Zhu, Bingjie Li, Zhuqing Liu, Lili Jia, Limin Zuo, , Zhentai Zhu, Guangzhi Shan,
Published: 1 May 2018
Journal: Toxicon
Toxicon, Volume 146, pp 24-30; https://doi.org/10.1016/j.toxicon.2018.03.006

Abstract:
Aflatoxin (AFB) is one of the most toxic fungal metabolites produced by Aspergillus flavus, which may contaminate food and agricultural products. Herein, an aptamer-based surface plasmon resonance (SPR) biosensor was developed to detect AFBs. The chosen aptamer showed comparable interaction with the two AFBs, namely aflatoxin B1 (AFB1) and aflatoxin B2 (AFB2). Such phenomenon was rarely reported, and might lead to a simultaneous detection of both AFBs. In this study, AFB1 was used to systematically establish the detection method. In the SPR system, streptavidin proteins were immobilized on the surface of a CM5 sensor chip as a cross-linker and biotin-aptamers were captured through streptavidin-biotin interaction. After optimization, the assay showed a dynamic range between 0.09 and 200 ng mL−1 (linear range from 1.5 to 50 ng mL−1 and a LOD of 0.19 ng mL−1) of AFB1 in buffer. As expected, the aptasensor showed high specificity towards AFB1 and AFB2, but hardly bound to other toxins with similar structures, including ochratoxin A (OTA), ochratoxin B (OTB), Zeralenone (ZEA) and T-2 toxin (T-2). Determination of AFB1 in vinegar was further performed using the SPR biosensor. Recoveries of AFB1 from spiked samples ranged from 96.3 to 117.8%. The developed SPR assay is a simple, fast and sensitive approach for the detection of residual AFBs in agricultural products and foodstuffs like vinegar.
Yueyuan Li, Lihui Tian, Li Liu, Malik Saddam Khan, Guanhui Zhao, , ,
Published: 1 March 2018
Journal: Talanta
Talanta, Volume 179, pp 420-425; https://doi.org/10.1016/j.talanta.2017.11.037

Abstract:
In this study, described an electrochemical immunoassay for insulin that is based on the use of zinc silicate spheres loaded with palladium nanoparticles (ZnSiO-PdNPs) that act as dual-function labels. The ZnSiO-PdNPs display high electrocatalytic activity towards the reduction of HO and high sensitivity in chronoamperometry. The ZnSiO-PdNPs decrease the electron transfer rate between the electrolyte and the surface of the electrode, which can increase the changed current and enhance the sensitivity of the immunosensor as detected by square wave voltammetry (SWV). Electrodeposited gold is used as the matrix material. The icosahedral gold nanocrystals are coated with the primary antibodies formed a 3D mode to against abundant of insulin. Under optimal conditions, the assay has a linear response in the 0.1pgmL to 50ngmL insulin concentration range, and the limit of detection of the SWV and CA methods are 0.25 fg mL and 80 fg mL, respectively. Moreover, the immunosensor holds an outstanding analytical performance for the insulin detection and has promising potential in clinical diagnosis.
Published: 1 March 2018
Biosensors and Bioelectronics, Volume 101, pp 199-205; https://doi.org/10.1016/j.bios.2017.10.030

Abstract:
We have constructed an aptamer immobilized gold atomic cluster mediated, ultrasensitive electrochemical biosensor (Apt/AuAC/Au) for LPS detection without any additional signal amplification strategy. The aptamer self-assemble onto the gold atomic clusters makes Apt/AuAC/Au an excellent platform for the LPS detection. Differential pulse voltammetry and EIS were used for the quantitative LPS detection. The Apt/AuAC/Au sensor offers an ultrasensitive and selective detection of LPS down to 7.94 × 10(-21)M level with a wide dynamic range from 0.01 attomolar to 1pM. The sensor exhibited excellent selectivity and stability. The real sample analysis was performed by spiking the diluted insulin sample with various concentration of LPS and obtained recovery within 2% error value. The sensor is found to be more sensitive than most of the literature reports. The simple and easy way of construction of this sensor provides an efficient and promising detection of an even trace amount of LPS.
Sandeep K. Vashist,
Published: 1 January 2018
The publisher has not yet granted permission to display this abstract.
Tamal Sarkar, Neethu Narayanan,
International Journal of Environmental Research, Volume 11, pp 591-601; https://doi.org/10.1007/s41742-017-0052-0

The publisher has not yet granted permission to display this abstract.
Emmanuel Matabaro, , Eric Uwimbabazi,
Comprehensive reviews in food science and food safety, Volume 16, pp 808-820; https://doi.org/10.1111/1541-4337.12287

The publisher has not yet granted permission to display this abstract.
Thitirat Putnin, Watthanachai Jumpathong, Rawiwan Laocharoensuk, ,
Artificial cells, nanomedicine, and biotechnology, Volume 46, pp 1042-1051; https://doi.org/10.1080/21691401.2017.1360322

Abstract:
This work focuses on fabricating poly(2-aminobenzylamine)-modified screen-printed carbon electrode as an electrochemical immunosensor for the label-free detection of human immunoglobulin G. To selectively detect immunoglobulin G, the anti-immunoglobulin G antibody with high affinity to immunoglobulin G was covalently linked with the amine group of poly(2-aminobenzylamine) film-deposited screen-printed carbon electrode. The selectivity for immunoglobulin G was subsequently assured by being challenged with redox-active interferences and adventitious adsorption did not significantly interfere the analyte signal. To obviate the use of costly secondary antibody, the [Fe(CN)6]4-/3- redox probe was instead applied to measure the number of human immunoglobulin G through the immunocomplex formation that is quantitatively related to the level of the differential pulse voltammetric current. The resulting immunosensor exhibited good sensitivity with the detection limit of 0.15 ng mL−1, limit of quantitation of 0.50 ng mL−1 and the linear range from 1.0 to 50 ng mL−1. Given those striking analytical performances and the affordability arising from using cheap screen-printed carbon electrode with label-free detection, the immunosensor serves as a promising model for the next-step development of a diagnostic tool.
Yueyuan Li, Malik Saddam Khan, Lihui Tian, Li Liu, Lihua Hu, Dawei Fan, Wei Cao, Qin Wei
Published: 1 March 2017
Analytical and Bioanalytical Chemistry, Volume 409, pp 3245-3251; https://doi.org/10.1007/s00216-017-0266-1

Abstract:
A sensitive label-free amperometric electrochemical immunosensor for detection of prostate-specific antigen (PSA) was proposed in this work. The nanocomposite of halloysite nanotubes with polypyrrole shell and palladium nanoparticles ([email protected]) was used as a novel signal label. The HNTs with adequate hydroxyl groups are economically available raw materials. PPy, as an electrically conducting polymer material, can be absorbed to the surface of HNTs by in situ oxidative polymerization of the pyrrole monomer and form a shell on the HNTs. The shell of PPy could not only improve the conductivity of the nanocomposite but also absorb large amounts of Pd nanoparticles (NPs). The Pd NPs with high electrocatalytic activity toward the reduction of H2O2 and the [email protected] nanocomposite as the analytical signal label could improve the sensitivity of the immunosensor. Under optimal conditions, the immunosensor showed a low detection limit (0.03 pg/mL) and a wide linear range (0.0001 to 25 ng/mL) of PSA. Moreover, its merits such as good selectivity, acceptable reproducibility, and stability indicate that the fabricated immunosensor has a promising application potential in clinical diagnosis. Graphical Abstract A new label-free amperometric electrochemical immunosensor based on [email protected] nanocomposite for quantitative detection of PSA.
, Joni Kilpijärvi, Maciej Sobocinski, , Antti Hassinen, Someshekar B. Prakash, Peter Möller, Pamela Abshire, Sakari Kellokumpu,
Published: 29 November 2016
Beilstein Journal of Nanotechnology, Volume 7, pp 1871-1877; https://doi.org/10.3762/bjnano.7.179

Abstract:
Cell viability monitoring is an important part of biosafety evaluation for the detection of toxic effects on cells caused by nanomaterials, preferably by label-free, noninvasive, fast, and cost effective methods. These requirements can be met by monitoring cell viability with a capacitance-sensing integrated circuit (IC) microchip. The capacitance provides a measurement of the surface attachment of adherent cells as an indication of their health status. However, the moist, warm, and corrosive biological environment requires reliable packaging of the sensor chip. In this work, a second generation of low temperature co-fired ceramic (LTCC) technology was combined with flip-chip bonding to provide a durable package compatible with cell culture. The LTCC-packaged sensor chip was integrated with a printed circuit board, data acquisition device, and measurement-controlling software. The packaged sensor chip functioned well in the presence of cell medium and cells, with output voltages depending on the medium above the capacitors. Moreover, the manufacturing of microfluidic channels in the LTCC package was demonstrated.
K. Yugender Goud, , Akhtar Hayat, Satyanarayana M., K. Vengatajalabathy Gobi, Jean Louis Marty
Published: 1 November 2016
Sensors and Actuators. B, Chemical, Volume 235, pp 466-473; https://doi.org/10.1016/j.snb.2016.05.112

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Kaveh Amini, Iraklii I. Ebralidze, Nora W. C. Chan,
Published: 22 September 2016
Analytical Methods, Volume 8, pp 7623-7631; https://doi.org/10.1039/c6ay01978a

Abstract:
Lipopolysaccharides (LPSs), also known as endotoxins, can be fatal even at low concentrations.
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