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

Advance Nanomaterials for Biosensors

The book provides a comprehensive overview of nanostructures and methods used to design biosensors, as well as applications for these biosensor nanotechnologies in the biological, chemical, and environmental monitoring fields. Biological sensing has proven to be an essential tool for understanding living systems, but it also has practical applications in medicine, drug discovery, food safety, environmental monitoring, defense, personal security, etc. In healthcare, advancements in telecommunications, expert systems, and distributed diagnostics are challenging current delivery models, while robust industrial sensors enable new approaches to research and development. Experts from around the world have written five articles on topics including:Diagnosing and treating intraocular cancers such as retinoblastoma; Nanomedicine in cancer management; Engineered nanomaterials in osteosarcoma diagnosis and treatment; Practical design of nanoscale devices; Detect alkaline phosphatase quantitatively in clinical diagnosis; Progress in the area of non-enzymatic sensing of dual/multi biomolecules; Developments in non-enzymatic glucose and H2O2 (NEGH) sensing; Multi-functionalized nanocarrier therapies for targeting retinoblastoma; Galactose functionalized nanocarriers; Sensing performance, electro-catalytic mechanism, and morphology and design of electrode materials; Biosensors along with their applications and the benefits of machine learning; Innovative approaches to improve the NEGH sensitivity, selectivity, and stability in real-time applications; Challenges and solutions in the field of biosensors

Electrochemical Sensors Based on Metal Nanoparticles with Biocatalytic Activity

Biosensors have attracted a great deal of attention, as they allow for the translation of the standard laboratory-based methods into small, portable devices. The field of biosensors has been growing, introducing innovations into their design to improve their sensing characteristics and reduce sample volume and user intervention. Enzymes are commonly used for determination purposes providing a high selectivity and sensitivity; however, their poor shelf-life is a limiting factor. Researchers have been studying the possibility of substituting enzymes with other materials with an enzyme-like activity and improved long-term stability and suitability for point-of-care biosensors. Extra attention is paid to metal and metal oxide nanoparticles, which are essential components of numerous enzyme-less catalytic sensors. The bottleneck of utilising metal-containing nanoparticles in sensing devices is achieving high selectivity and sensitivity. This review demonstrates similarities and differences between numerous metal nanoparticle-based sensors described in the literature to pinpoint the crucial factors determining their catalytic performance. Unlike other reviews, sensors are categorised by the type of metal to study their catalytic activity dependency on the environmental conditions. The results are based on studies on nanoparticle properties to narrow the gap between fundamental and applied research. The analysis shows that the catalytic activity of nanozymes is strongly dependent on their intrinsic properties (e.g. composition, size, shape) and external conditions (e.g. pH, type of electrolyte, and its chemical composition). Understanding the mechanisms behind the metal catalytic activity and how it can be improved helps designing a nanozyme-based sensor with the performance matching those of an enzyme-based device. GRAPHICAL ABSTRACT: [Image: see text

Design, development and characterization of nanostructured electrochemical sensors

This is a publication-based thesis which focuses on the study of electrochemical microbiosensors for glucose detection. It investigates applications of a series of microfabricated gold electrodes based on several nanostructures in electrochemical biosensing technologies, embracing three major methodologies: direct electro-catalytic detection, enzymatic detection and dual-enzyme cascade detection. The study is described over five main chapters with a sixth providing a summary of the material presented and perspectives for the future. Chapter 1 provides an introduction to the field of the electrochemical biosensors with a specific focus on the chosen nanostructures and miniaturized systems, as well as a brief history of the biosensor. Chapter 2 presents results published in ACS Applied Nanomaterials, 2019, 2, 9, 5878-5889. It demonstrates the enzyme free detection of glucose via a direct electro-catalytic reaction. The miniaturized band array electrodes with specific width, length and inter-electrode-distance were integrated with homogeneously distributed copper foam nano dendrites. Such foam deposits presented for the first time at the micro scale were achieved using the in-situ hydrogen bubble template method. The resulting very high electroactive surface area of the porous foam deposits was one of the major advantages in terms of achieving superior performance from each micro band foam electrode towards glucose detection. Moreover, both sensors also showed a strong resistance to the poisoning effects of chloride ions and displayed excellent stability over a period of three months.Chapter 3 presents the first of t wo sets of results for the enzymatic detection of glucose, results published in Elsevier Electrochimica Acta, 2019, 293, 307-317. Chapter 4 then presents the second set of results on this topic which is published in and Elsevier Electrochimica Acta, 2019, 298, 97-105. The aim of these two chapters is to discuss the effect of miniaturization on the enzymatic biosensor performance which was studied in the presence of a carbon quantum dot (CQD) and gold nanoparticle nanohybrid system. CQDs, are a new class of carbon-based materials and have been used here for the first time as a matrix component integrated onto microfabricated gold electrode surfaces for enzyme immobilization and further miniaturization. The biosensors developed were studied by electrochemistry to investigate the analytical performance of each device. By scaling down the surface area of the biosensor, a 13-times increase in sensitivity was achieved towards glucose. Moreover both sensors-planar, micro disk array- exhibited excellent reproducibility, reusability and operational stability in terms of the performance of biosensors. Chapter 5 presents results published in RSC Analyst, 2020 (DOI: 10.1039/C9AN01664C). It demonstrates the operation of a dual-enzyme cascade which was constructed onto a micro band array electrode based on glucose oxidase and horseradish peroxidase enzymes. To achieve a very high surface area, a porous gold-foam was electrodeposited onto surface and then a second electrodeposition layer of chitosan and multi walled carbon nanotube nano-bio-composite. The micro band cascade scheme developed exhibited the highest sensitivity towards glucose detection in comparison to other systems reported in the literature. Chapter 6 provides an insight into the field of electrochemical biosensing with the support of the achievements presented in this thesis. Thus, by taking advantage of the available system, this chapter discusses the possible future applications of the electrochemical biosensors. The thesis then ends with section 7 which presents some Appendices

Electrospun Nanofibers for Label-Free Sensor Applications

Electrospinning is a simple, low-cost and versatile method for fabricating submicron and nano size fibers. Due to their large surface area, high aspect ratio and porous structure, electrospun nanofibers can be employed in wide range of applications. Biomedical, environmental, protective clothing and sensors are just few. The latter has attracted a great deal of attention, because for biosensor application, nanofibers have several advantages over traditional sensors, including a high surface-to-volume ratio and ease of functionalization. This review provides a short overview of several electrospun nanofibers applications, with an emphasis on biosensor applications. With respect to this area, focus is placed on label-free sensors, pertaining to both recent advances and fundamental research. Here, label-free sensor properties of sensitivity, selectivity, and detection are critically evaluated. Current challenges in this area and prospective future work is also discussed

Pectin modified metal nanoparticles and their application in property modification of biosensors

Pectin is a structural anionic heteropolysaccharide and abundantly found in the cell wall of terrestrial trees and plants. It exhibits several advantageous properties such as non-toxicity, cheap, biodegradable, biocompatible, abundant, flexible, etc. Functional groups like carboxylic acid and hydroxyl make pectin suitable to be covalently bonded with other biomolecules and proteins. Based on these properties, pectin is being extensively employed to encapsulate/coat metal nanoparticles (MNPs) to inhibit their aggregation and enhancing the suitability of MNPs for a wide range of applications in healthcare like drug delivery, antimicrobial activity, antioxidant etc. Another important application of pectin is to enhance the electrochemical performances of sensors in which electrode materials are modified with pectin, which immobilizes the enzyme without disturbing the basic electron transfer properties of the electrode. Thus pectin is found to have great potential for developments in future in various fields like sensing, drug delivery etc. This review covers the application of pectin for MNPs stabilization and electrochemical sensors to improve their properties. The review also emphasizes synthetic strategies and electrochemical analysis of analytes. This review will provide a comprehensive overview of pectin’s applicability and can help to design novel and efficient MNPs and electrochemical sensors for a wide range of applications

The Development of Polymer-coated Electrodes for Chemical Detection

This research focuses on the development of simple and cost effective approaches for making electrochemical sensors with a great sensitivity and selectivity. As an economic and abundant starting material, organic substrates were investigated to making conductive polymers that showed promising electrocatalytic activities. Firstly, a poly(4-bromoaniline) film was successfully synthesized on a gold electrode and the porous film which was made up of nano-ribbons on the Au electrode was used for the recognition of amino acids enantiomers. Secondly, different halogen ions were introduced to manifest the properties of the synthesized polymers. The results show that bromide ions have significantly inhibited the transition of leucoemeraldine to emeraldine, letting the PANI polymer to be in Pernigraniline form, which exhibited much improved performance in pH sensing. In addition, a simple way to controllably deposit copper nanoparticles inside poly-2,5-dimethoxyaniline matrix, which can be employed as a glucose sensor, was developed