Molecular Imprinted Polymers Coupled to Photonic Structures in Biosensors: The State of Art

Optical sensing, taking advantage of the variety of available optical structures, is a rapidly expanding area. Over recent years, whispering gallery mode resonators, photonic crystals, optical waveguides, optical fibers and surface plasmon resonance have been exploited to devise different optical sensing configurations. In the present review, we report on the state of the art of optical sensing devices based on the aforementioned optical structures and on synthetic receptors prepared by means of the molecular imprinting technology. Molecularly imprinted polymers (MIPs) are polymeric receptors, cheap and robust, with high affinity and selectivity, prepared by a template assisted synthesis. The state of the art of the MIP functionalized optical structures is critically discussed, highlighting the key progresses that enabled the achievement of improved sensing performances, the merits and the limits both in MIP synthetic strategies and in MIP coupling

Applications of Molecularly Imprinted Films

Molecularly imprinted polymers are materials that have voids that are complementary in shape, size, and electronic environment to a specific molecule used for preparation, known as the template. These voids are specific recognition sites that bind the templates preferentially and are used specifically for biomimetic sensors and for solid-phase extraction. Because the specific surface is very important during this process, the use of films and membranes is preferred. This book contains four articles dedicated to sensor application (three research articles and one review) and one research article dedicated to solid-phase extraction

Electrochemically synthesized polymers in molecular imprinting for chemical sensing

This critical review describes a class of polymers prepared by electrochemical polymerization that employs the concept of molecular imprinting for chemical sensing. The principal focus is on both conducting and nonconducting polymers prepared by electropolymerization of electroactive functional monomers, such as pristine and derivatized pyrrole, aminophenylboronic acid, thiophene, porphyrin, aniline, phenylenediamine, phenol, and thiophenol. A critical evaluation of the literature on electrosynthesized molecularly imprinted polymers (MIPs) applied as recognition elements of chemical sensors is presented. The aim of this review is to highlight recent achievements in analytical applications of these MIPs, including present strategies of determination of different analytes as well as identification and solutions for problems encountered

Soft and flexible material-based affinity sensors

Recent advances in biosensors and point-of-care (PoC) devices are poised to change and expand the delivery of diagnostics from conventional lateral-flow assays and test strips that dominate the market currently, to newly emerging wearable and implantable devices that can provide continuous monitoring. Soft and flexible materials are playing a key role in propelling these trends towards real-time and remote health monitoring. Affinity biosensors have the capability to provide for diagnosis and monitoring of cancerous, cardiovascular, infectious and genetic diseases by the detection of biomarkers using affinity interactions. This review tracks the evolution of affinity sensors from conventional lateral-flow test strips to wearable/implantable devices enabled by soft and flexible materials. Initially, we highlight conventional affinity sensors exploiting membrane and paper materials which have been so successfully applied in point-of-care tests, such as lateral-flow immunoassay strips and emerging microfluidic paper-based devices. We then turn our attention to the multifarious polymer designs that provide both the base materials for sensor designs, such as PDMS, and more advanced functionalised materials that are capable of both recognition and transduction, such as conducting and molecularly imprinted polymers. The subsequent content discusses wearable soft and flexible material-based affinity sensors, classified as flexible and skin-mountable, textile materials-based and contact lens-based affinity sensors. In the final sections, we explore the possibilities for implantable/injectable soft and flexible material-based affinity sensors, including hydrogels, microencapsulated sensors and optical fibers. This area is truly a work in progress and we trust that this review will help pull together the many technological streams that are contributing to the field

Novel Electrochemical Biosensors for Clinical Assays

Biosensors, i.e., devices where biological molecules or bio(mimetic)structures are intimately coupled to a chemo/physical transducer for converting a biorecognition event into a measurable signal, have recently gained a wide (if not huge) academic and practical interest for the multitude of their applications in analysis, especially in the field of bioanalysis, medical diagnostics, and clinical assays. Indeed, thanks to their very simple use (permitting sometimes their application at home), the minimal sample pretreatment requirement, the higher selectivity, and sensitivity, biosensors are an essential tool in the detection and monitoring of a wide range of medical conditions from glycemia to Alzheimer’s disease as well as in the monitoring of drug responses. Soon, we expect that their importance and use in clinical diagnostics will expand rapidly so as to be of critical importance to public health in the coming years. This Special Issue would like to focus on recent research and development in the field of biosensors as analytical tools for clinical assays and medical diagnostics

New strategies for developing receptors based on molecular imprinting for analytical applications

434 p.La presente tesis se ha basado en la síntesis y aplicación de polímeros de huella molecular (MIP) para elanálisis químico del 4-etilfenol y los compuestos pertenecientes a su ruta metabólica, que son el etil esterde ácido cumárico, el ácido cumárico y el vinilfenol. Los fenoles volátiles como el 4-etilfenol y el 4-vinilfenol afectan a las características organolépticas del vino, siendo perjudiciales en altasconcentraciones. El nivel de 4-etilfenol es proporcional a la concentración y la actividad de la levaduraresponsable de su aparición en vino, y por lo tanto puede ser utilizado como un indicador de su presencia.El trabajo experimental se ha sido divido en dos secciones principales, en función de la técnica analíticaen la que ha sido implementado el material impreso desarrollado. Inicialmente, se presenta unametodología para el desarrollo y aplicación de fases estacionarias basadas en MIP. Los materialesdesarrollados han sido evaluados como fases estacionarias en extracción en fase sólida y cromatografíalíquida.Como segundo apartado del trabajo, se describen distintas técnicas de impresión molecular para suimplementación en sensores voltamperométricos, por un lado, la síntesis de películas MIP sobreelectrodos de oro y por otro, la síntesis de nanopartículas MIP y su posterior inmovilización en lasuperficie de electrodos de oro

Sensing at nanostructures for agri-food and enviromental applications

With a predicted population increase of 2.3 billion people, by 2050, agricultural productivity must be vastly improved and made sustainable. Globally, agriculture must deliver a 60% increase in food production to cope with the population demand. Moreover, this needs to be achieved against a changing climate, an exploitation of natural resources, and growing water and land scarcities. New digital technologies can optimise production efficiency and ensure food security and safety while also minimising waste within the production systems and the supply chain. To this end, new sensor technologies are being developed for applications in animal health diagnostics and environmental issues related to the global population, such as food & crop protection, pathogen and toxin detection, and environmental remediation. In this thesis, two new nanosensing diagnostic devices are developed and presented; surface enhanced Raman sensing and electrochemical sensing. Surface-enhanced Raman spectroscopy (SERS) substrates were fabricated by templating a flexible thermoplastic polymer against an aluminium drinks can followed by coating with a silver film, to produce a rough nanostructured metallic surface. SERS is used for both qualitative (molecular fingerprint) and quantitative detection of dye molecules and food toxins. In addition, the SERS technique is also applied in combination with nanoelectrochemical square wave voltammetry to detect nano-concentrations of neonicotinoid pesticides. The enhanced sensitivity and minimum sample preparation requirements provide tremendous opportunities for food safety and security sectors. An impedimetric immunosensor device (with a micro SD style pin-out) was also developed for the serological diagnosis of viruses and antibodies associated with bovine respiratory disease and bovine liver fluke. The silicon chip devices consist of six on-chip nanoband electrodes which can be independently modified with a polymer layer for covalent immobilisation of capture and target biomolecules. This electrochemical biosensor technology provides label-free and cost-efficient sensing capability in a compact size, and demonstrates the potential development of immunoassay-based point-of-use devices for on-farm diagnosis or therapeutic monitoring in animal health applications