On-site Screening Research Articles

Theoretical and experimental validation of the use of hydraulic load cells in fit-for-purpose assessment of structural bolt assemblies

ABSTRACT A hydraulic load cell is a simple onsite load measurement device for quality assurance of structural fasteners. While these load cells can be used to establish torque-tension relationship, due to their reduced stiffness compared to electronic load cells, prominent standards such as EN14399-2 prevents the use of hydraulic load cells in bolt assemblies testing where nut rotational angle is also of importance. Since the significant angular parameter used in EN14399-2 is a difference of two angles, it can be argued that when the difference of angle is considered, the reduced stiffness effect of hydraulic load cell could be negated. This paper provides both theoretical and experimental validation of using an electronic and a hydraulic load cell to carry out the fit-for-purpose assembly test as prescribed in EN14399-2. Results show that a hydraulic load cell can be used as a simple onsite screening test to improve quality assurance of structural bolt assemblies on construction sites. The Australian Standard for fastener assemblies AS/NZS 1252:2016 requires a test regime to ensure the supplied bolts are suitable for its intended application. The methodology developed in this paper maybe used to screen the quality of the supplied fasteners on-site before being used in the assembly.

Endonuclease-driven DNA walking for constructing a novel colorimetric and electrochemical dual-mode biosensing method

The development of methods to realize the on-site analysis of antibiotic pollutants is of great importance for food quality control and environmental monitoring. Herein, we designed a magnetic bead (MB)-based DNA walker and utilized its target-triggered and endonuclease-driven walking reaction to develop a novel colorimetric and electrochemical dual-mode biosensing method for the convenient detection of kanamycin (Kana) antibiotic. The colorimetric signal transduction strategy of the method was constructed on the telomerase extension of the DNA walking-released telomeric primer into G-quadruplex/hemin DNAzymes. Due to the DNA walking and telomerase dual signal amplification, a good linear relationship from 0.1 pg mL−1 to 1 ng mL−1 was obtained for this strategy with a detection limit of 22 fg mL−1. Meanwhile, the MB complex produced through the above DNA walking reaction was also used as a multipedal DNA walker to develop an electrochemical signal transduction strategy. By utilizing it to trigger another endonuclease-driven DNA walking at a DNA hairpin-modified electrode, ferrocene labels were quantitatively released from this electrode to cause the electrochemical signal decrease. Because of the dual endonuclease-driven DNA walking for signal amplification, a five-order of magnitude wide linear relationship from 0.01 pg mL−1 to 1 ng mL−1 was obtained with an ultralow detection limit of 8.4 fg mL−1. As the two strategies did not involve complicated manipulations and the requirement of expensive instruments, this biosensing method exhibits a high application value for the on-site semiquantitative screening and accurate analysis of antibiotic residues.

Hybrid 3D printed integrated microdevice for the determination of copper ions in human body fluids.

On-site screening of copper ions in body fluid plays a critical role in monitoring human health, especially in heavy pollution areas. In this study, we have developed a hybrid 3D printed integrated microdevice for the determination of copper ions in human body fluids. A fixed and low volume of sample was detected by using the integrated microdevice without any preprocessing. The hybrid channel enables sample uniform mixing and quantitative dilution with buffer solution by inducing the “horseshoe vortex” phenomenon. The electrolytic microcell based on the flow detection system shows a more effective copper ion reaction ratio and, as a result, a better sensitivity. The simulation of the finite element method (FEM) determined the relevant optimum parameters of the hybrid channel and the microcell. The design, fabrication, and detection procedure of the integrated microdevice are here illustrated. The microdevice presented superior detection properties towards copper ions. The calibration curves covered two linear ranges varying from 20 to 100 ppb and 100 to 400 ppb, respectively. The limit of detection was estimated to be 15 ppb (S/N = 3). The relative standard deviation of the peak current measurements was 2.26%. The designed microdevice was further applied to detect copper ions in practical samples (calf serum sample and synthetic human urine sample) using a standard addition method, and the average recovery was found to be 95–104%. The performance of copper ion detection with the integrated microdevice was consistent with that of the inductively coupled plasma mass spectrometry (ICP-MS) in the same practical samples, demonstrating significant practicality in the test of body fluidics. The portable integrated microdevice is an excellent choice for on-site detection and has a promising prospect in the point-of-care testing (POCT) applications.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s00216-022-04049-9.

Dual-modal nanoplatform integrated with smartphone for hierarchical diabetic detection

On-site screening of diabetes and precise diagnosis of diabetic complications may provide a conduit for early intervention and disease burden reduction. However, stratified metabolic analysis needs designed materials for colorimetric detection of targeted biomarkers and direct metabolic fingerprinting of the native blood. Here, an advanced dual-modal nanoplatform is constructed based on PdPtAu alloys, which serve both as the nanoenzymes in colorimetric sensing for targeted metabolite quantitation and as matrix in laser desorption/ionization mass spectrometry for untargeted metabolic fingerprinting. The platform achieved rapid glucose quantitation toward point-of-care testing of 27 participants and identified diabetic retinopathy from diabetic population with a sensitivity and specificity of 84.6%. We further assessed the generalizability of the nanoplatform for real-case applications, through the captured digital images and computing resources equipped in smartphones. The results advance the design of material-based platforms for stratified metabolic analysis and display promise to fit in the current hierarchical medical system in practice.

Research on the implementation method of loom monitoring

A loom monitoring system was designed and developed to realize monitoring loom in both industrial field and remote network environments and to meet the on-site workers’ convenient operation and centralized management of enterprises. This article uses the touch screen as the main carrier of the field system and cooperates with configuration technology and expert system to realize fault diagnosis. And this article uses the B/S architecture as the remote system cloud platform network architecture which builds the Redis database and Nginx server operating environment, and the front-end technology such as HTML5 is used to design a web client interface to meet the functional needs. This implementation method has three advantages: First, it breaks the traditional way of mechanical button matching with touch screens in the textile manufacturing industry; second, it can quickly find out the reason for loom failure; and third, it lifts the regional restrictions, thus improving the intelligence and information level of textile machinery and equipment.Article HighlightsThis monitoring system combines configuration technology with computer technology to realize monitoring in both industrial fields and remote environments. Industrial site workers quickly and directly operate the loom through the on-site touch screen. Enterprise management personnel centrally manage the loom through remote means. Therefore, the system is convenient for different types of users in the enterprise.The industrial field monitoring system has comprehensive functions and friendly interface operation, which realizes the comprehensive monitoring and operating parameter setting of each link of the loom production. It can also meet functional requirements such as fault alarm and debugging and maintenance.The use of the cloud platform and other technologies to achieve remote monitoring of the loom, breaking through the geographical restrictions. It is possible to log in to the remote system anytime and anywhere to monitor the running status and production information of the loom, which also provides convenience for later maintenance and upgrades.

Microfluidic paper-based aptasensor devices for multiplexed detection of pathogenic bacteria

Foodborne pathogens are major public health concerns worldwide. Paper-based microfluidic devices are versatile, user friendly and low cost. We report a novel paper-based single input channel microfluidic device that can detect more than one whole-cell foodborne bacteria at the same time, and comes with quantitative reading via image analysis. This microfluidic paper-based multiplexed aptasensor simultaneously detects E. coli O157:H7 and S. Typhimurium. Custom designed particles provide colorimetric signal enhancement and false results prevention. Several aptamers were screened and the highest-affinity aptamers were optimized and employed for detection of these bacteria in solution, both in a buffer as well as pear juice. Image analysis was used to read and quantify the colorimetric signal and measure bacteria concentration, thus rendering this paper based microfluidic device quantitative. The colorimetric results show linearity over a wide concentration range (102CFU/mL to 108CFU/mL) and a limit of detection (LOD) of 103CFU/mL and 102CFU/mL for E. coli O157:H7 and S. Typhimurium, respectively. An insignificant change in colorimetric response for non-target bacteria indicates the aptasesnors are specific. The reported multiplexed colorimetric paper-based microfluidic devices is likely to perform well for on-site rapid screening of pathogenic bacteria in water and food products.

Lessons learned from staging the Olympics during a pandemic

Lessons learned from staging the Olympics during a pandemic

Functional nucleic acid lateral flow magnetic biosensor based on blocking the super PCR and magnetic test strip for rapid detection of genetically modified maize MON810†

Although PCR is a typical temperature-variable amplification technique for nucleic acids, it still faces challenges in rapid screening, such as low speed, poor sensitivity, inferior visualization, and weak stability. In this paper, a universal functional nucleic acid (FNA) lateral flow magnetic biosensor was constructed using blocking super PCR (BS-PCR) and a magnetic test strip (MTS). In theory, the visualized and magnetic output of dsDNA-based amplicons were achieved via ssDNA/dsDNA conversion by blocking linkers in the PCR primers and magnetic probes. In application, high-speed, super-sensitive, highly stable rapid screening was realized by taking advantage of the speediness of the super PCR reactor and the anti-background interference, visualization and high stability of magnetic signal readout. The genetically modified maize MON810 was selected as a double-stranded model target, while 5-min BS-PCR and 5-min magnetic signal readouts achieved the screening results within 10 min. Furthermore, the exponential PCR amplification and magnetic-based sensibilization improved the sensitivity to a single copy. This biosensor is simple and portable, with significant potential for rapid on-site screening.

Nanozyme enhanced paper-based biochip with a smartphone readout system for rapid detection of cyanotoxins in water

Cyanobacterial harmful algal blooms in freshwater systems can produce cyanotoxins, such as microcystins (MCs) and nodularins (NODs), presenting serious threats to human health and ecosystems. Required routine monitoring of cyanotoxins in water samples, as posed by U.S. EPA drinking water contaminant candidate list 5 (CCL5), demands for cost-effective, reliable and sensitive MCs/NODs detection methods. We report the development of a colorimetric paper-based immunochip assisted by nanozyme catalysis with a smartphone readout system for rapid detection of cyanotoxins in water. We show that the introduction of biorthogonal click reaction enables in situ facile self-assembly of multi-layers of peroxidase-like nanozyme onto the anti-MCs/NODs monoclonal antibody. We can detect 13 variants of MCs/NODs even in the sub-microgram per liter range with detection limit of below 0.7 μg/L and satisfactory recovery percentages between 88 and 120% in different water matrices. Our technology shows a good correlation with the well-developed ELISA technology, demonstrating its great potential applications in resource-limited or less-developed regions for on-site and large-scale screening of cyanotoxins in water environment.

Regulation Mechanism of ssDNA Aptamer in Nanozymes and Application of Nanozyme-Based Aptasensors in Food Safety.

Food safety issues are a worldwide concern. Pathogens, toxins, pesticides, veterinary drugs, heavy metals, and illegal additives are frequently reported to contaminate food and pose a serious threat to human health. Conventional detection methods have difficulties fulfilling the requirements for food development in a modern society. Therefore, novel rapid detection methods are urgently needed for on-site and rapid screening of massive food samples. Due to the extraordinary properties of nanozymes and aptamers, biosensors composed of both of them provide considerable advantages in analytical performances, including sensitivity, specificity, repeatability, and accuracy. They are considered a promising complementary detection method on top of conventional ones for the rapid and accurate detection of food contaminants. In recent years, we have witnessed a flourishing of analytical strategies based on aptamers and nanozymes for the detection of food contaminants, especially novel detection models based on the regulation by single-stranded DNA (ssDNA) of nanozyme activity. However, the applications of nanozyme-based aptasensors in food safety are seldom reviewed. Thus, this paper aims to provide a comprehensive review on nanozyme-based aptasensors in food safety, which are arranged according to the different interaction modes of ssDNA and nanozymes: aptasensors based on nanozyme activity either inhibited or enhanced by ssDNA, nanozymes as signal tags, and other methods. Before introducing the nanozyme-based aptasensors, the regulation by ssDNA of nanozyme activity via diverse factors is discussed systematically for precisely tailoring nanozyme activity in biosensors. Furthermore, current challenges are emphasized, and future perspectives are discussed.

On-Site Analyses as a Decision Support Tool for Dredging and Sustainable Sediment Management

Beneficial use of dredged sediments, either in harbours or waterways, is based on their potential as alternative resources. Such sediments can be considered as bulk materials for industrial needs, which is predicated on their current waste status or meeting end-of-waste constraints. They also can be an integral part of beneficial use projects using sediments as a bulk component, including civil engineering and landscaping. This is particularly important for beneficial use projects focusing on climate change effects mitigation, such as flood protection works, coastline defence or littoral urban areas redevelopment. When dredged sediment is used as a bulk material, its acceptability is based on an assumed homogeneity of its properties. On-site analyses allow pre-dredging detailed mapping at a denser scale than laboratory ones; monitoring dredgings during operations and during processing; and continuous control of their properties at the implementation site. This is currently possible only for a selection of inorganic analytes. When dredgings are part of a larger beneficial use project, on-site analyses facilitate first the baseline survey and the sediment source characterisation. Continuous monitoring of the sediment load allows a fast detection of contamination hot spots and their adequate management. Site survey via on-site instruments allow end users and communities to check themselves the contamination level, hence acceptability is better. On-site dredged sediment analyses monitor both building properties and environmental compliance; soil and sediment analyses at receiving sites; surface and groundwater, either for impact assessment or for monitoring works. On-site instruments provide immediate results and allow dynamic or adaptive sampling strategies, as well as allowing operational decisions in real time. Confirmation by laboratory analyses is required for validation, but on-site sample screening for laboratory analyses improves their efficiency. The present paper was developed on the basis of an earlier presentation, which it developed and updated extensively.

A comparative study of “turn-off” mode and “turn-on” mode lateral flow immunoassay for T-2 toxin detection

The “turn-off” mode lateral flow immunoassay (LFA) based on the conventional competitive format and “turn-on” mode LFA mainly determined by inner filter effect (IFE-LFA) were objectively compared using T-2 toxin as a model molecule and T-2-BSA and anti-T-2 monoclonal antibody as immunocomplex pairs to improve the sensitivity of the LFA. First, Au nanoparticles (Au NPs), amorphous carbon nanoparticles (ACNPs), quantum dots nanospheres (QDs), and time-resolved fluorescent microspheres (TRFMs) were selected as labels for developing the “turn-off” mode LFAs (Au NPs-LFA, ACNPs-LFA, QDs-LFA, and TRFMs-LFA, respectively). Thereafter, Au NPs and ACNPs were used as absorbers, and QDs and TRFMs were selected as fluorescers, for preparing the “turn-on” mode IFE-LFAs (IFE-LFA based on Au NPs as absorbers and QDs as fluorescers [Au NPs-mAb-QDs-BSA], IFE-LFA based on Au NPs as absorbers and TRFMs as fluorescers [Au NPs-mAb-TRFMs-BSA], IFE-LFA based on ACNPs as absorbers and QDs as fluorescers [ACNPs-mAb-QDs-BSA], and IFE-LFA based on ACNPs as absorbers and TRFMs as fluorescers [ACNPs-mAb-TRFMs-BSA]). Under optimized conditions, the naked-eye observation cut-off values for the aforementioned eight LFAs were 4, 2, 2, 2, 3, 2, 1.5, and 1 ng/mL, with quantitative limit of detection values of 0.50, 0.23, 0.24, 0.23, 0.47, 0.45, 0.27, and 0.22 ng/mL, respectively. Among all LFAs, ACNPs-mAb-TRFMs-BSA showed the highest sensitivity. The results of this study provide a perspective for improving the sensitivity of the LFAs to meet the requirements of on-site screening for trace substances.

Evaluation of portable vibrational spectroscopy for identifying plasticizers in dairy tubing

ABSTRACT Plasticisers are commonly used to increase the flexibility of a wide variety of food contact materials including the plastic tubing, liners, and gaskets used in the dairy industry. In recent years, some classes of plasticisers have come under scrutiny due to the potential for transfer of these compounds into the milk itself, which can then be further processed into foods such as powdered milks and cheeses, infant formula, and baked goods. One such set of plasticisers that is being evaluated for frequency of use, potential routes of exposure, and risk to consumers is ortho-phthalates, hereafter referred to as phthalates. In order to better understand the actual use of phthalate versus non-phthalate plasticised tubing, a robust, rapid, and portable analytical method is necessary for on-site screening. Laboratory Raman and near-infrared spectrometers have been used extensively for polymer and additive evaluation, and advances in portable/hand-held technology could lead to feasible plasticiser evaluation in the field. This research overviews efforts to evaluate six portable spectroscopy devices for their ability to identify phthalate versus non-phthalate plasticised polyvinyl chloride (PVC) dairy tubing, liners, and gaskets. The most successful method, a hand-held Raman spectrometer along with a plasticiser spectral library or a chemometric model, can rapidly and accurately identify phthalate containing PVC and has the potential to be employed as a future field screening technique for regulators and the dairy industry.

A wide-range pH indicator based on colorimetric patterns of gold@silver nanorods

The potential of hydrogen (pH) is a basic and critical parameter representing the function of numerous chemicals/biomolecules. Due to the widespread applications of pH in diverse fields, the development of rapid and simple yet reliable probes for the determination of pH has attracted significant interest. In this paper, by using AuNRs, silver ions, and ascorbic acid as colorimetric pH sensor, a multicolorimetric nanosensor is described for pH measurement. The reduction of silver ions by ascorbic acid which is strongly influenced by pH, results in silver nanoshell deposition on the surface of AuNRs. Consequently, the formation of Au@Ag core-shell NRs causes a series of blue shifts in the longitudinal peaks of AuNRs and elegant color changes according to pH values ranging from 2.0 to 12.0. As a result of spectral shifting, distinct color variations were observed from brownish pink/light green color (acidic media) to dark green/blue color (neutral media) and eventually purple/brown color (basic media). Furthermore, a paper-based analytical device (PAD) was introduced for on-site pH screening. The pH-sensitive PAD was simply fabricated by immobilizing AuNRs on the surface of filter paper. Finally, the developed plasmonic probe was validated to be capable of accurate pH monitoring in urine, spoiled meat, drinking water, and seawater samples.

Computer-Aided Detection of Retinopathy of Prematurity Severity in Preterm Infants via Measurement of Temporal Vessel Width and Angle.

Retinopathy of prematurity (ROP) is a retinal disorder that occurs in preterm infants with low birth weight and is the leading cause of preventable blindness in children. Early identification of high-risk patients and early diagnosis and timely treatment of ROP can substantially improve patients' visual outcomes. However, manual screening consumes both time and resources. Telescreening using retinal fundus images has the potential to reduce the burden engendered by the necessity of on-site screening. Recently, substantial progress has been made in using computer-aided diagnosis with retinal fundus images, and this approach has attracted considerable attention for the diagnosis of eye diseases. Abnormalities of and alterations in retinal blood vessels may relate to the occurrence and progression of ROP. In this study, we examined the hypothesis that ROP severity may be associated with the angle and width of arteries and veins. We computationally determined the artery–artery and vein–vein angles in the temporal quadrants—the temporal artery angle (TAA) and temporal vein angle (TVA)—under normal conditions and in different ROP stages. We also estimated retinal vessel width—temporal artery width (TAW) and temporal vein width (TVW)—by applying the Radon transform method to fundus images. Our results revealed significant decreases in TAA and TVA and increases in TAW and TVW with increasing ROP severity (all P < 0.0001).In addition, we observed positive TAA–TVA and TAW–TVW correlations (both P < 0.0001). The TAA was negatively correlated with the TAW (r = −0.162, P = 0.0314). These retinal vessel features may be useful in assisting ophthalmologists in the early detection of ROP and its progression.

A Sensitive Aptasensor Using Biotin-Streptavidin System for Patulin Detection in Apple Juice.

Patulin contamination in fruits, vegetables, and their products is considered a serious health risk factor for food safety and human health. Thus, a rapid, simple detection method for patulin is becoming important, which could provide a tool for routine screening and food surveys. The objective of this study was to develop a sensitive aptamer-based lateral flow assay (FLA) using Streptavidin functionalized gold nanoparticles for sensitive patulin detection. An excellent dynamic range for patulin detection was obtained (2.7~139.8 ng/mL in the buffer and 7.07~359.5 ng/mL in the sample) with no affinity for other mycotoxins such as zearalenone (ZEN), ochratoxin A (OTA), aflatoxin B1 (AFB1), citrinin or tenuazonic acid (TEA). The limit of detection was 0.19 ng/mL in the buffer and 0.36 ng/mL in the real sample. The recoveries were 83.3% to 107.1%, with a satisfactory RSD value from 6.5% to 7.5%. Hence the established LFA could be used as a rapid, simple, on-site screening tool for PAT determination in apple juice.

An ultrasensitive colloidal gold immunosensor to simultaneously detect 12 beta (2)-adrenergic agonists

In this study, we first prepared a selective monoclonal antibody against 12 beta (2)-adrenergic agonists (Salbutamol, Clenbuterol, Brombuterol, Clenpenterol, Mabuterol, Carbuterol, Cimbuterol, Mapenterol, Pirbuterol, Terbutaline, Cimaterol, and Clenproperol). Then three haptens were designed and derived, among which, haptenS3 used the amino group of the salbutamol analog to derive a carboxyl group containing a spacer, which is unique to this study. The half-maximal inhibitory concentration (IC50) values were 0.35 ng/mL (Salbutamol), 0.42 ng/mL (Clenbuterol), 0.78 ng/mL (Brombuterol), 0.88 ng/mL (Clenpenterol), 1.34 ng/mL (Mabuterol), 1.38 ng/mL (Carbuterol), 1.71 ng/mL (Cimbuterol), 2.24 ng/mL (Mapenterol), 2.25 ng/mL (Pirbuterol), 2.27 ng/mL (Terbutaline), 3.49 ng/mL (Cimaterol), and 4.89 ng/mL (Clenproperol). We further developed a monoclonal antibody-based colloidal gold immunochromatographic test strip for screening and detecting 12 beta (2)-adrenergic agonists in swine urine and lamb samples. The immunochromatographic method developed in this study is a suitable tool for the on-site rapid detection and screening of beta (2)-adrenergic agonists in swine urine and lamb samples.

Dual-readout fluorescence quenching immunochromatographic test strips for highly sensitive simultaneous detection of chloramphenicol and amantadine based on gold nanoparticle-triggered photoluminescent nanoswitch control

Herein, a novel fluorescence quenching immunochromatographic test strip (FQICTS) for simultaneous detection of chloramphenicol (CAP) and amantadine (AMD) was developed on the basis of inner filter effect (IFE), with the combination of gold nanoparticles (AuNPs) and highly luminescent green-emitting gold nanoclusters (AuNCs) as the IFE quencher/donor pair. The AuNPs could quench the excitation light and emission light of AuNCs and achieve a high IFE efficiency due to dual spectral overlapping. Under optimal conditions, the “turn-on” mode of the AuNCs-based dual-readout FQICTS showed good linearity for CAP detection in chicken samples from 0.05 ng/g to 10 ng/g, with a limit of detection (LOD) of 0.043 ng/g. The linear range of AMD is 0.5–50 ng/g, with LOD of 0.45 ng/g. The visual LODs of CAP and AMD in “turn-on” mode were 200 and 10 times lower than that in “turn-off” mode, respectively. The “turn-on” mode of FQICTS showed high recovery for detecting CAP (82.5–94.5%) and AMD (81.9–110.7%) spiked into chicken samples. The performance and practicability of the established method were verified with commercial enzyme-immunoassay kits, and good correlations were observed. Overall, the newly developed AuNCs-based dual-readout FQICTS is a promising on-site screening tool for rapid, high-sensitivity detection of multiple food contaminants in practical applications.

Development of cost-effective fabrication process for on-site methamphetamine detection by adsorbable SERS substrate

In this study, the adsorbable SERS substrate was successfully fabricated on polydimethylsiloxane (PDMS) with the nanometer-sized roughness existing in a micrometer-sized roughness (nano-in-micro rough) structure which was completely transferred from the laser engraving aluminum (Al) mold by a replication process. Then the silver nanoparticle (Ag NPs) was deposited by magnetron sputtering. The physical morphology of the obtained samples was characterized by a field emission scanning electron microscope (FE-SEM). The ability for direct adsorb trace detection of the methylene blue (MB) on the glass slide surface was investigated. From the results, the SERS signal of the prepared adsorbable SERS substrates was influenced by the topography of the nano-in-micro rough feature and Ag NPs. It was found that combined nano-in-micro rough and microgroove structures exhibit high sensitivity of MB (10−5 M). In addition, the optimum adsorbable SERS substrate was then applied in practical application by adsorbing the methamphetamine (MAP) residues on the glass slide surface with a limit of 10−2 M, which could be expected to be an on-site screening platform for drugs detection.

A fluorescent aptasensor for the detection of Aflatoxin B1 by graphene oxide mediated quenching and release of fluorescence

Aflatoxin B1 contamination in food and agro commodities has been major concern of global food safety and trade industry. There is an urgent need to develop sensitive and on-site detection methods for aflatoxins mainly, AFB1 monitoring. In the present study, a fluorophore (Alexa Fluor 488) based aptamer biosensor was devised in combination with graphene oxide (GO) for the detection of Aflatoxin B1 (AFB1). The optimized diagnostic procedure consisted of a fluorescent modified aptamer (Ax-AFLA5) as detection probe and GO mediated quenching of the same; to the quenched system AFB1 was added resulting in subsequent release of fluorescence. The principle of GO based adsorption of ssDNA and successive desorption in the presence of target mycotoxin was utilised in development of the bioassay. In presence of target mycotoxin, the GO adsorbed ssDNA attained a structural conformation resulting in desorption and subsequent release of fluorescence. Assay parameters such as concentration of fluorescent probe, GO and incubation time were evaluated and optimized. The optical signal thus generated could determine presence of AFB1 in the given sample. Selectivity of the method with other mycotoxins was evaluated. The linear range of AFB1 from 0.2–200 ppb was assessed. Visible green fluorescence release was observed at 20 ppb under UV transilluminator and the detection limit of the developed assay was interpreted as 20 ppb of AFB1. The suitability of the assay for AFB1 quantification in groundnut and natural samples was also evaluated. Thus, the developed assay can be a field deployable, reliable and rapid alternative tool for onsite screening method of aflatoxins and other mycotoxins at field level.