Developments in nanoparticles for use in biosensors to assess food safety and quality

The following will provide an overview on how advances in nanoparticle technology have contributed towards developing biosensors to screen for safety and quality markers associated with foods. The novel properties of nanoparticles will be described and how such characteristics have been exploited in sensor design will be provided. All the biosensor formats were initially developed for the health care sector to meet the demand for point-of-care diagnostics. As a consequence, research has been directed towards miniaturization thereby reducing the sample volume to nanolitres. However, the needs of the food sector are very different which may ultimately limit commercial application of nanoparticle based nanosensors. © 2014 Elsevier Ltd

Smartphone-based food diagnostic technologies: A review

A new generation of mobile sensing approaches offers significant advantages over traditional platforms in terms of test speed, control, low cost, ease-of-operation, and data management, and requires minimal equipment and user involvement. The marriage of novel sensing technologies with cellphones enables the development of powerful lab-on-smartphone platforms for many important applications including medical diagnosis, environmental monitoring, and food safety analysis. This paper reviews the recent advancements and developments in the field of smartphone-based food diagnostic technologies, with an emphasis on custom modules to enhance smartphone sensing capabilities. These devices typically comprise multiple components such as detectors, sample processors, disposable chips, batteries and software, which are integrated with a commercial smartphone. One of the most important aspects of developing these systems is the integration of these components onto a compact and lightweight platform that requires minimal power. To date, researchers have demonstrated several promising approaches employing various sensing techniques and device configurations. We aim to provide a systematic classification according to the detection strategy, providing a critical discussion of strengths and weaknesses. We have also extended the analysis to the food scanning devices that are increasingly populating the Internet of Things (IoT) market, demonstrating how this field is indeed promising, as the research outputs are quickly capitalized on new start-up companies

Lateral Flow Assay for <em>Salmonella</em> Detection and Potential Reagents

Salmonella is among the very important pathogens threating human and animal health. It is a common food pathogen transmitted from animals to humans via contaminated food, drinking water, and air. It invades the intestinal tract of hosts and causes salmonellosis leading to death. S. enteritidis was the most common species accounted for all salmonellosis cases. S. typhimurium is also another significant species causing the serious cases worldwide. To ensure public health, early detection of pathogens is crucial. Lateral flow assay (LFA), immunochromatographic assay, is a simple and rapid diagnostic test kits used in various fields and can be developed by, aptamers, antibodies (Abs), and nucleic acids. They are also being continued to develop different capture reagents coming from the recombinant technology. It has many advantages such as having mature technology, market presence, low cost, easy to use for end users without education, and stable shelf life. Gold nanoparticles (GNPs) are the most commonly used labels in the LFAs for the naked-eye analysis. Therefore, Salmonella detection by LFA based on GNPs in a rapid and simple way is always open to be developed by new reagents and methods

Up-Converting Nanoparticle-Based Immunochromatographic Strip for Multi-Residue Detection of Three Organophosphorus Pesticides in Food

Organophosphorus (OP) pesticides are widely used to control pests because of their high activity. This study described a rapid and sensitive lateral flow immunochromatographic (LFIC) assay based on up-converting nanoparticles (UCNPs) for multi-residue detection of three OP pesticides. The developed assay integrated novel fluorescent material UCNPs labeled with a broad-specific monoclonal antibody. Based on the competitive platform by immobilized antigen in the test zone, the optimized UCNPs-LFIC assay enabled sensitive detection for parathion, parathion-methyl, and fenitrothion with IC50 of 3.44, 3.98, and 12.49 ng/mL (R2 ≥ 0.9776) within 40 min. The detectable ability ranged from 0.98 to 250 ng/mL. There was no cross-reactivity with fenthion, phoxim, isocarbophos, chlorpyrifos, or triazophos, even at a high concentration of 500 ng/mL. Matrix interference from various agricultural products was also studied in food sample detection. In the spiked test, recoveries of the three OP pesticides ranged from 67 to 120% and relative standard deviations were below 19.54%. These results indicated that the proposed strip assay can be an alternative screening tool for rapid detection of the three OP pesticides in food samples

Lateral flow immunoassays with fluorescent reporter technologies

Lateral flow assays (LFAs) are user-friendly diagnostic test devices most commonly known from the home pregnancy tests. Since their appearance in the market in 1980’s, LFAs have become well-established and products have been developed for various applications, but the most commonly sold LFAs still have the same basic features as the early products. Compared to other rapid diagnostic test (RDT) platforms, the main benefits of LFAs include inexpensive manufacturing costs, relatively fast assay development process, and the stand-alone capability of the test to be used without any instrumentation. The analytical membrane that provides the solid support for the bioassay reagents and allows the liquids to migrate through the binder lines by capillary force is almost exclusively manufactured of nitrocellulose. As the nitrocellulose remains the most widely used material, its optical properties, mechanical robustness, and chemical stability are not optimal for the RDT development. However, the established status of the nitrocellulose membrane in the RDT industry and the continuous product development suggests that the material will remain in LFAs for years to come. Typically, in LFAs, the coloured reporter particles form visible lines on the analytical membrane depending on the presence or absence of the analyte of interest. The visible lines can be interpreted visually without any instrumentation. However, the visual assessment of the assay read-out is prone to subjectivity in interpretation and can be affected by poor lighting conditions. Moreover, the visual read-out can only be used to generate a qualitative or a semi-quantitative result. The versatility of the lateral flow technology can be improved by using efficiently quantifiable reporter technologies such as fluorescent nanoparticles. However, the drawback of pursuing high analytical sensitivity and quantitative results by fluorescent reporter is the apparent need for a reader instrument. With fluorescent reporters, the optical properties of the assay membranes and sample fluids must be considered in order to achieve minimal interference to the detection of the reporters. Autofluorescence originating from the assay materials can be avoided by using the upconverting nanoparticle (UCNP) detection technology. Nevertheless, the non-analyte specific background signal can still occur from non-specific binding of the reporter particles. The aim of the thesis is to explore the opportunities arising from the use of different fluorescent reporter particles to improve the analytical sensitivities of LFAs, and to evaluate the feasibility of fluorescent reporter particles as a substitute for common visually detectable reporters. Exploiting the increased detectability of the reporter particles to improve the assay sensitivity requires careful re-optimization of the assay conditions

Quantum Dots-Based Immunochromatographic Strip for Rapid and Sensitive Detection of Acetamiprid in Agricultural Products

In this study, a rapid and sensitive immunochromatographic strip (ICS) assay, based on quantum dots (QDs), was developed for the qualitative and quantitative detection of acetamiprid in agricultural samples. Acetamiprid-ovalbumin conjugates (ACE-OVA) and goat anti-mouse IgG were sprayed onto a nitrocellulose membrane as a test and control line. Two kinds of anti-acetamiprid monoclonal antibodies (mAb) obtained in our lab were characterized by the ELISA and surface plasmon resonance assay. The competitive immunoassay was established using a QDs-mAb conjugate probe. The visual detection limit of acetamiprid for a qualitative threshold was set as 1 ng/mL to the naked eye. In the quantitative test, the fluorescence intensity was measured by a portable strip reader and a standard curve was obtained with a linear range from 0.098 to 25 ng/mL, and the half maximal inhibitory concentration of 1.12 ng/mL. The developed method showed no evident cross-reactivities with other neonicotinoid insecticides except for thiacloprid (36.68%). The accuracy and precision of the developed QDs-ICS were further evaluated. Results showed that the average recoveries ranged from 78.38 to 126.97% in agricultural samples. Moreover, to test blind tea samples, the QDs-ICS showed comparable reliability and a high correlation with ultra-performance liquid chromatography-tandem mass spectrometry. The whole sample detection could be accomplished within 1 h. In brief, our data clearly manifested that QDs-ICS was quite qualified for the rapid and sensitive screening of acetamiprid residues in an agricultural product analysis and paves the way to point-of-care testing for other analytes

ADVANCED IMMUNOSENSING PLATFORMS FOR BIOMONITORING AND ENVIRONMENTAL MONITORING

Chemical analysis of complex sample matrix is significant towards the efficient monitoring of human and environmental health. In the area of environmental contamination control and disease diagnosis, traditional analytical approaches rely on the separation effects by chromatography, such as gas chromatography (GC) and liquid chromatography (LC). Although GC/LC coupled with various detectors are extensively employed in analytical settings as the mature technologies, the disadvantages are also obvious, including the dependence on large and bulky instruments, complex and time-consuming instrumental operation, inevitable sample pretreatment and high cost. These disadvantages greatly limit their application in rapid diagnosis of disease, on-site samples testing, and household preclinic diagnosis. Immunosensing approaches, however, are promising substitutes applicable to the above scenarios. Featured with extraordinary selectivity and accuracy of detection attributed to the specific antibody-antigen recognition, immunoassays (IAs) have attracted extensive interests in recent years. Nevertheless, the major challenges are to overcome the inherent defects of IAs, such as low sensitivity of detection and difficult to realize multi-target simultaneous detection, in the meantime, to develop high-performance portable detection platforms. In this dissertation, advanced immunosensing platforms based on the principle of enzyme-linked immunosorbent assay (ELISA) and lateral flow immunoassay (LFIA) were systematically explored from the aspects of biorecognition, signal amplification, and signal quantification. Advanced functional nanomaterials, including metal-organic framework (MOF), graphene, carbon dot, mesoporous nanocomposite, etc., with unique physical or chemical properties were synthesized and employed as signal reporters in IAs for amplified sensitivity of detection. In addition, we designed and manufactured immunosensing platforms using 3D printing to achieve optimal integration of immunoassays, nanomaterials, and quantitative detection methods, thus the on-site, point-of-care, high-performance sample assessment was realized. Further, the extraordinary analytical performances of the immunosensing platforms were validated in practical applications for the detection of woodsmoke biomarkers in various human biofluids representing the exposure of human to contaminated air from wildfires, as well as the detection of environmental pesticide contaminants and the corresponding human metabolites in biofluids

Developments in nanoparticles for use in biosensors to assess food safety and quality

The following will provide an overview on how advances in nanoparticle technology have contributed towards developing biosensors to screen for safety and quality markers associated with foods. The novel properties of nanoparticles will be described and how such characteristics have been exploited in sensor design will be provided. All the biosensor formats were initially developed for the health care sector to meet the demand for point-of-care diagnostics. As a consequence, research has been directed towards miniaturization thereby reducing the sample volume to nanolitres. However, the needs of the food sector are very different which may ultimately limit commercial application of nanoparticle based nanosensors

Paper-Based Point-of-Care Tools for Blood Testing

Early detection of malignant disease is crucial for timely diagnosis and effective medical intervention, which significantly increases survival rates and reduce financial burden on patients. Biomarkers are becoming increasingly important in detection of malignant diseases, because they can be employed for indicating diseases, predicting risks and monitoring the progression of diseases. In addition, biomarkers show up at early stages of diseases in human tissues and fluids (e.g., blood, urine and saliva), which shows great promise for early disease detection. In this dissertation, paper-based lateral flow strips (PLFSs) have been developed for the detection of disease biomarkers, including protein biomarkers and microRNA (miRNA) biomarkers from clinical samples and whole blood samples. Among most of the reported biosensors, PLFSs appear to be an effective tool for providing access to point-of-care (POC) applications, due to low cost, fast response, portability and ease of use. In addition, paper is compatible with biological samples, which allows its application in analyzing various biomolecules. However, conventional PLFSs exhibit insufficient sensitivity and poor interference resistance. In particular whole blood samples, which contain numerous interference biomolecules, substantially affect detection accuracy and specificity. In this dissertation, several strategies have been employed to solve the problems, including introducing PLFSs with ultrasensitive techniques, meanwhile modifying PLFSs with functional nanomaterials and paper accessory unit to reduce the interference biomolecules from human fluids. In summary, five chapters will be demonstrated: (1) Surface-enhanced Raman scattering (SERS) technique modified PLFSs for protein biomarker detection in clinical blood plasma samples. In this chapter, silica coated SERS nanoparticles (NPs) have been developed for improving Raman signal and detection sensitivity, at the same time, silica coating of the SERS NPs substantially improve the stability of the NPs in complex human fluids. As a result, the developed SERS-PLFS can realize direct detection of neuron-specific enolase (NSE) from clinical blood plasma samples of traumatic brain injury (TBI) patients. The test results of the SERS-PLFSs were compatible with those from the standard enzyme-linked immunospecific assay (ELISA) method; (2) Blood plasma separation unit (PSU) integrated PLFS for cancer protein biomarker detection from whole human blood sample. In this chapter, a paper based PSU was fabricated to efficiently retain red blood cells (RBCs) inside the unit to block their migration and meanwhile push the target protein contained plasma to the detection area of the PLFS. As a result, cancer protein biomarker-carcinoembryonic antigen (CEA) was successfully detected by the PSU-PLFS from whole blood samples; (3) Plasmonic chip and PSU integrated PLFS for protein biomarker detection from whole blood. In order to meet the high sensitivity demand, a gold nanopyramid array functionalized chip was integrated into a PLFS for amplifying Raman signal and ultrasensitive detection of TBI protein biomarker s-100β; while the PSU was utilized to reduce the RBCs interference from whole blood. As a result, compared with the result of the SERS-PLFS in Chapter 2, an improvement in LOD with two-order of magnitude was obtained; (4) Near-infrared fluorophores (NIRFs) functionalized PLFS for miRNA detection from blood plasma. In this chapter, NIRFs encapsulated silica nanoparticles were synthesized and incorporated into a PLFS for stroke biomarker miRNA-34 detection. Compared with a single fluorescent dye, the synthesized NIRF NPs encapsulated numerous fluorophores into one single silica nanoparticle, exhibiting amplified luminescent intensity. Moreover, the NIRF nanoparticles minimized the fluorescent background from biological matrices and test strip materials, which elevates signal-to-noise ratio and anti-interference capacity; (5) Duplex specific nuclease (DSN) based signal amplification strategy modified PLFS for ultrasensitive miRNA detection in blood plasma. In order to meet the high sensitivity demand of miRNA-34 measurement from the clinical blood plasma of stroke patient, the developed NIRFs-PLFS in Part 4 was further elevated with DSN modification for amplifying fluorescent signal. As a result, the DSN-PLFS exhibited an improvement in detection sensitivity with two-orders of magnitude in blood plasma