Rapid Antibody-based Technologies in Food Analysis

Richard OKennedy, Richard OKennedy

• Publisher: Royal Society of Chemistry
• Year: 2019
• ISBN:
  9781788017916
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Analytic Chemistry

There are significant challenges in food analysis, problems with food contamination and authentication, and a worldwide need to ensure food safety.

This book provides a description of antibody-based technologies used in food analysis. It focuses on key applications, outlining the approaches used, their advantages and limitations, and describes future areas for development. Chapters are written by experts in the field, critically examining each of the currently used methodologies and highlighting new evolving technologies, such as lab-on-chip and microfluidics-based devices and biosensors. Case studies demonstrating the utility of each of the methods described are included. Important introductory chapters cover sample preparation for analysis and statistical sampling necessary for quality control for verification of results. An overview chapter highlighting major analytical issues and areas that have specific requirements, e.g. food authentication, is provided.

Researchers and scientists in the field who have to acquire, verify and use technologies for food analysis, food producers and processors, food safety and testing laboratories, and government agencies will all find this a useful addition to their library.

CHAPTER 1

Introduction to Antibody-based Food Analysis

Richard O'Kennedy^*a,b

^a School of Biotechnology, Dublin City University, Dublin 9, Ireland

^b Hamad Bin Khalifa University and Research Development and Innovation, Qatar Foundation, Doha, Qatar
*E-mail: [email protected]

This book provides a description of antibody-based technologies used in food analysis, which are widely applied and offer significant advantages when linked to a range of detection stratagems. In this book all the key elements associated with the use of antibody-based detection strategies are addressed ranging from the structure and production of antibodies to established and newly applied detection platforms.

This book provides a description of antibody-based technologies used in food analysis. It focuses on key applications outlining the approaches used, their advantages and limitations and areas for future development. Each chapter is written by an expert or experts in the field who are highly conversant with the relevant topic being examined and its applications in the food area. A number of case studies demonstrating the utility of the methods described is included. To ensure that all key areas are covered, chapters include descriptions of sample preparation for analysis, often a major issue with foods, statistical sampling necessary for quality control, and the use of specific approaches, e.g. statistical, for verification of results. In addition, new technologies with significant potential use in specific facets of food analysis are included. These are by no means exhaustive but highlight novel strategies and platforms that offer significant opportunities for deployment to address key analytical challenges.

Currently we are faced with major global challenges in terms of ensuring food quality given the variety of foods and food components that are regularly and continuously transported around the world.^1,2 Foods are by their nature very complex with multiple ingredients which need to be determined. In addition to the expected constituents there is a crucial need to ensure that no adulterants are present and that the types and source of ingredients are indeed authentic and expected. Food is also perishable, so the analysis may well need to be determined very quickly not only to exclude harmful effects but also to allow rapid safe movements of food from producer to consumer. Producers, suppliers and government control agencies must be able to certify that food and food components are safe for the consumer and, equally, that contaminated and unsafe material is removed from the food chain as quickly as possible.

In setting out to develop this book it was decided to focus on antibody-based approaches as these are widely applied and offer significant advantages when linked to a range of detection stratagems. Antibodies can be generated against a vast range of food components, food toxins and adulterants arising from the food itself, or from pathogenic organisms such as microbes and also from environmental contaminants.^3,4 In addition, foods are often exposed to a variety of potential adulterants during production, for example pesticides or antibiotics, and many of these can be detected effectively using antibodies specifically designed to assay them. Initially polyclonal antibodies were used but in some cases there were issues with reproducibility and specificity. The availability of monoclonal antibodies that could detect very specific epitopes with high sensitivity greatly enhances the diagnostic capability of antibodies, and the capacity to produce large quantities of identical antibodies continuously overcame one of the major issues associated with polyclonal antibodies due to heterogeneity and batch-to-batch variation. However, polyclonal antibodies are still widely used. They are often the only type of antibody available for a particular target and are used very widely as secondary detection antibodies in a variety of analytical technologies/platforms.

Significant advantages arose with the availability of recombinant approaches.⁵ Major advantages associated with recombinant antibodies are that they can be tailored to the specific requirements of the assay in terms of sensitivity, specificity, size, addition of chemistries or tags to aid immobilization, and the availability of multiple expression/production strategies. The specificity can be engineered to be highly specific or indeed broadened so that the antibody can react with a whole class of compounds. Such approaches have proved to be of huge significance in terms of clinically applied therapeutic approaches, e.g. in cancer. However, for diagnostics, and specifically food diagnostics, much can be achieved if recombinant antibodies are fully exploited. This relates to both direct analyses of specific analytes and isolation/concentration of analytes from complex food matrices.

One of the major challenges in food analysis relates to the complexity of the matrix, which can lead to difficulties associated with interferences in assay performance characteristics. For example, with antibodies this could be associated with cross-reactivity of the antibody used in the assay with molecules or entities having closely related epitopes. Errors can also occur where the antibody might bind in a non-specific manner to a component in the food; it is vital that relevant controls are included to allow for such issues. Very rigorous characterization and screening approaches for antibodies are also necessary to minimize or preferably eliminate such effects.⁶

In many cases it may be necessary to detect targets present in very small quantities, e.g. with microbial pathogens.⁴ Traditionally this was addressed by taking food samples and applying them to selective media enriched with key constituents to preferentially allow the growth of the targeted pathogen. The assay would then be performed on samples derived following such enrichment. However, this approach takes time and ideally the assay should be sufficiently sensitive and selective to remove the need for such enrichment. Additional complications can arise if constituents of the food sample itself may affect the growth capacity of the target microbe in the medium and this need always to be determined, especially with new formulations. In many cases where targets are present in very low quantities concentration steps may also be necessary prior to analysis, e.g. in large liquid samples. This may be addressed by using antibodies linked to magnetized particles, which can then be concentrated using columns that bind the antibody–bead–target complex. The concentrated target can then be more easily quantified.

Nowadays there is significant pressure to develop methods that are cheap and easy to use with minimum complications and user inputs. This approach facilitates the application of testing on produce at an early stage, e.g. detection of viruses in growing plants in the field or in analysis of corn immediately after harvesting. Such approaches allow the early detection of problems which can potentially be addressed by suitable treatments or segregation of contaminated material before it is mixed with clean batches. The early warning of problems ensures that contamination is eliminated as speedily as possible from the food chain. While subsequent confirmation testing may require the use of lab-based methods, which are often complex and expensive, the ‘on-site’ approach offers a first line of defence in our efforts to maximize the quality and authenticity of the components of the food chain.^3,7 This point-of-use approach, now widely being applied in the healthcare sector, certainly offers great benefits for rapid analysis and will become much more important in the future. Key issues to be addressed include the need for high levels of specificity and sensitivity, rapidity of use, robustness in terms of coping with difficult matrices, simplicity of measurement for users, and the ability to routinely quantify the target analytes at the levels required The ability to capture, carefully quality control, use, and record data, e.g. using mobile phone-based detection, is an important requirement. An additional need is to be able to follow carefully how the food ingredients were tested and the results obtained at all stages of the process ‘from field to fork’.⁶

In this book all the key elements associated with the use of antibody-based detection strategies are addressed, ranging from the structure and production of antibodies to established and newly applied detection platforms. It is envisaged that this approach will be of significant value to the established analyst seeking to understand new approaches that are being developed. In addition, it should be of importance to researchers and those seeking to develop and authenticate new methods. The descriptions of detection technologies now being developed should provide significant insights in terms of potential novel applications.

Increasingly there are needs for the detection of multiple complex analytes ranging from complex biological components to small molecules such as pesticides; this is certainly the case for food analysis. The development of multiplexed systems capable of measuring many targets concurrently is therefore essential. Indeed, some of the main challenges relate to the selection of antibodies with significantly different detection ranges, determined by the needs for analyte determination and their incorporation into systems that can accommodate such differences in a highly effective manner.

When assembling the expertise to produce this book it was necessary to also address key issues related to quality control and how this is addressed in relation to antibody-based methods. This is crucial for any assay procedure, as rigorous validation is an absolute requirement. An added complication that is becoming more evident is that analytes are often present in food in conjugated forms although they may become unconjugated either through processing or when the food is eaten, and these conjugated forms may be less easy to detect.

Increasingly the microbiome is seen to play a crucial role in food utilization by both animals and humans. It is clear that food constituents can be differentially modified depending on the microbial environment and this in turn may offer additional analytical challenges.

Food authentication is now clearly recognized as a vital area for food analysis and this may offer additional problems where the origin, species or production and treatment of food ingredients needs to be verified and where efforts have been made to nullify or avoid the effectiveness of currently employed quality control processes.

It is highly likely that future food-based analyses will involve a plethora of tests including mass spectrometric analysis, nucleic acid-based tests and antibody tests to adequately encompass the analysis of all constituents present. Indeed, new analytical platforms now emerging incorporate entire assays and the associated steps with minimal user intervention. These platforms use microfluidics-based systems to successfully incorporate all steps ranging from sample addition to detection, with the results being generated in minutes. Although many such platforms are still being developed, some are already commercially available and well established, particularly for clinical analyses.⁸

As this area further develops one can envisage multiple test formats and assay approaches all being combined in a single system. This would be of highly significant benefit to all sectors of the food industry.

In summary, therefore, this book consists of an up-to-date compendium of key antibody-based technologies used in food analysis by leading experts. It focuses on major areas of analytical need required by food producers, processors and associated quality assurance labs. The advantages/limitations of methodologies and areas of ongoing and future development are highlighted. Other texts cover all methods of food analysis, but this results in less focus, lack of depth and inadequate coverage of advantages and limitations, points that are crucial to users. It is hoped that readers will find this book valuable and informative and that it will help to effectively address current and future challenges for antibody-based food analysis.

Acknowledgements

I wish to acknowledge all the inputs of the authors and of the editorial and production teams at the Royal Society of Chemistry, particularly Katie Morrey, Sylvia Pegg and Noah Tate. Their help was absolutely vital in making this book a reality. I would also like to thank the Qatar Foundation and Dublin City University, and the associated funding bodies for their support. Finally I would like to thank my wife, Kristina, and my family, for their patience, forbearance and support during the evolution of this book from an idea to the final manuscript.

References

1. P. Leonard, S. Hearty, J. Brennan, L. Dunne, J. Quinn and T. Chakraborty, Enzyme Microb. Technol., 2003, 32(1), 313.

2. B. Byrne, E. Stack, N. Gilmartin and R. O'Kennedy, Sensors, 2009, 9(6), 44074445.

3. D. A. McPartlin, J. H. Loftus, A. S. Crawley, J. Silke, C. S. Murphy and R. J. O'Kennedy, Curr. Opin. Biotechnol., 2017, 45, 164169.

4. N. Gilmartin, M. S. Gião, C. W. Keevil and R. O'Kennedy, Int. J. Food Microbiol., 2016, 219, 5055.

5. H. Ma and R. O'Kennedy, Methods, 2017, 116, 2333.

6. R. O'Kennedy, S. Fitzgerald and C. Murphy, TrAC, Trends Anal. Chem., 2017, 89, 5359.

7. D. A. McPartlin and R. J. O'Kennedy, Expert Rev. Mol. Diagn., 2014, 14(8), 979998.

8. R. O'Kennedy, J. Fitzgerald, A. Cassedy, A. Crawley, X. Zhang and S. Carrera, J. Micromech. Microeng., 2018, 28(6), 063001.

CHAPTER 2

Production and Use of Antibodies

B. Vijayalakshmi Ayyar^†*a, Sushrut Arora^†b and Richard O'Kennedy^{c, d}

^a Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA

^b Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA

^c School of Biotechnology, Dublin City University, Dublin 9, Ireland

^d Hama...

Table of contents

• Cover
• Half Title
• Series Editor
• Title
• Copyright
• Contents
• Chapter 1 Introduction to Antibody-based Food Analysis 1
• Chapter 2 Production and Use of Antibodies 6
• Chapter 3 The Importance of Bioanalytical Parameters and Statistical Analysis in Immunoassays for Food Analytes 32
• Chapter 4 Designing Appropriate Immunoassays for Food Analysis 46
• Chapter 5 Targeting Marine Toxins and Other Adulterants in Fish 75
• Chapter 6 Mycotoxins: Contamination, Control and Analyses 112
• Chapter 7 New Chip-based Technologies for Rapid Analysis of Food Contaminants 139
• Chapter 8 Applications of Immuno-electrochemical Detection Strategies for Food Analysis 154
• Chapter 9 The Use of Flow-based Technologies for Food Analysis 175
• Chapter 10 Novel Recombinant Antibody and Protein-based Approaches for Analysis of Food and Food Contaminants with Particular Relevance to Asia 195
• Chapter 11 Optical and Acoustic Label-free Instrumentation for Molecular Detection with a Focus on Food 223
• Chapter 12 Applications of Recent Developments in Microfluidics for Rapid Analysis of Food Safety and Quality 256
• Chapter 13 Antibody-based Sensors for the Detection of Pathogens of Potato and Barley 282
• Chapter 14 Detection of Food Taints and Contaminants Using Novel Engineered Antibodies 308
• Chapter 15 New and Evolving Challenges and Strategies for Effective Food Analysis 330