DOCTOR OF PHILOSOPHY Development of bioanalytical approaches as model tools for the rapid detection of pesticides Bin Salom, Abdullah Award date: 2018 Awarding institution: Queen's University Belfast Link to publication Terms of use All those accessing thesis content in Queen’s University Belfast Research Portal are subject to the following terms and conditions of use • Copyright is subject to the Copyright, Designs and Patent Act 1988, or as modified by any successor legislation • Copyright and moral rights for thesis content are retained by the author and/or other copyright owners • A copy of a thesis may be downloaded for personal non-commercial research/study without the need for permission or charge • Distribution or reproduction of thesis content in any format is not permitted without the permission of the copyright holder • When citing this work, full bibliographic details should be supplied, including the author, title, awarding institution and date of thesis Take down policy A thesis can be removed from the Research Portal if there has been a breach of copyright, or a similarly robust reason. 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Sep. 2021 Development of bioanalytical approaches as model tools for the rapid detection of pesticides By Abdullah Bin Salom This thesis is submitted to the Queen’s University Belfast for the degree of Doctor of Philosophy Institute for Global Food Security School of Biological Sciences Faculty of Medicine, Health and Life Sciences Queen’s University Belfast October 2017 i Thesis Acknowledgement I am grateful to Allah Almighty for the good health and well-being that were necessary to complete this long journey. I gratefully acknowledge my employer, the Saudi Food and Drug Authority, for sponsoring my PhD studies as well as understanding the challenges that I have faced during all these years. I would like to express my sincere gratitude to my supervisor, Dr. Katrina Campbell, for her continuous support of my PhD study and related research, and for her patience, motivation, and immense knowledge. Her guidance has helped my research and the writing of this thesis. In addition, my sincere thanks also goes to my ex-supervisors, Dr. Iva Chianella and Professor Mohammed Zourob, for their encouragement, insightful comments and continued support, even after I moved from Cranfield University. I am also grateful to Sara, a post-doctoral research fellow, and Tom, a technician both of whom worked within the Institute for Global Food Security. I am extremely thankful for their shared expertise and valuable guidance. I am also grateful to all the laboratory staff for their assistance. I would also like to thank my fellow doctoral students for their feedback, cooperation and of course friendship. I am also grateful to my son, Basil, for his patience and emotional support during my PhD studies. ii Summary Pesticides are chemicals used internationally in the agricultural sector to repel and kill pests. However, misuse or misapplication of pesticides can cause detrimental effects for humans and animals, including livestock and non-target organisms. In addition, many studies have linked pesticides with certain adverse symptoms and death. As a result, regulatory authorities around the world monitor pesticide levels in food supplies and update maximum residue levels as needed. As part of addressing the concerns of pesticide presence in food stocks, rapid, sensitive and cheap methods for sample preparation and early detection systems need to be developed to detect pesticide residues in food for on- site analysis before it reaches consumers. The introduction to Chapter 1 discusses pesticide classifications and their use in food production, regulations governing pesticides, their use and current methods used for pesticide analysis. Also, molecularly imprinted polymers (MIPs) and biosensors related to organophosphate pesticides (OPPs) were discussed. It addresses MIP production, synthesis and different materials involved in these processes that occur in the literature, including templates, functional monomers, cross-linkers, initiators and solvents. In addition, this review discusses various analytical applications, such as solid-phase extraction, chromatographic columns, biosensors and catalysis as well as the use as micro- and nanoparticles. Furthermore, it outlines current pesticide detection methods employed in environmental and food safety applications. It discusses the materials and biosensors used for target enrichment and pre-concentration processes, recognition elements such as enzymes, antibody whole-cells, MIPs and aptamers, and other techniques that use free recognition elements and nanoparticles to construct biosensors for OPPs detection. Chapter 2 discusses the development of MIPs, of which the first attempt used precipitation polymerisation before thermos-polymerisation methods to evaluate four different porogens (acetonitrile, dichloromethane, chloroform and toluene) and their impact on MIP affinity and selectivity. Initially, chlorpyrifos (CPF) and chlorpropham (CIPC) were selected as templates and the synthesised MIPs were evaluated for solid phase extraction (SPE) application in both organic and aqueous solutions as loading iii carriers. However, only the MIP prepared using acetonitrile as the porogen for CPF in aqueous solution as the carrier showed promising results that allowed for a full optimisation for future work. During this study polymer capacity, washing solutions and selectivity were also investigated. Chapter 3 focuses on the development of a detection system based on an immune-optical planar waveguide biosensor for the rapid selective individual screening of two organophosphate pesticides, chlorpyrifos (CPF) and parathion (PT). The assay conditions were investigated and optimised for CPF detection using MBio assay buffer in a single assay. A cross-reactivity study with pesticides of similar structure was performed in buffer, which showed high selectivity towards CPF. To demonstrate a real application, the biosensor assay was evaluated for the determination of CPF in strawberries at the maximum residue level of 200µg/kg using a simple extraction and dilution approach. For the detection of PT, a broad specificity antibody was employed. The method was first investigated and optimised in MBio assay buffer for sensitivity and selectivity of the assay and then evaluated for the detection of other pesticides of similar chemical structure. The results indicated that the biosensor recognized a number of pesticides. The biosensor assay was again evaluated for the determination of parathion in strawberries. Due to the lower maximum residue level required of 50µg/kg and to improve the sensitivity of the assay, an additional sample preparation step in drying the strawberry extracts and reconstituting them in buffer was necessary. Chapter 4 advances the work discussed in Chapters 3, and describes the development of a proof of concept approach to create a multiplex microarray to detect two agricultural pesticides, CPF and PT, simultaneously in one assay using a multiplex MBio planar waveguide biosensor. However, due to the challenges and complexities of the antibodies employed the results showed that the multiplex assay was not accurate for the detection of both pesticides due to the cross-reactivity of the antibody used to detect PT in this study. Nonetheless, the results of the MBio planar waveguide biosensor used in this research have demonstrated that rapid individual assays have been developed for CPF and PT. Due to the portability of this technology, these results are promising for field analysis with improvements in sample preparation and sensitivity being required. In addition, for both pesticides, the multiplex assay remains a possible concept for iv transferring this technology to the field of pesticide analysis for multiple pesticide detection and recognition. However, instead of purchasing commercial antibodies as required due to time constraints in this project, the design of highly specific antibodies for individual pesticides would be preferential. v TABLE OF CONTENTS Thesis Acknowledgement ............................................................................................... ii Summary ........................................................................................................................ iii TABLE OF CONTENTS ............................................................................................. vii LIST OF FIGURES ..................................................................................................... xiii LIST OF TABLES ..................................................................................................... xviii LIST OF ABBREVIATIONS ...................................................................................... xx Chapter 1: Literature review .......................................................................................