Polymers and plastics modified electrodes for biosensors: a review

Polymer materials offer several advantages as supports of biosensing platforms in terms of flexibility, weight, conformability, portability, cost, disposability and scope for integration. The present study reviews the field of electrochemical biosensors fabricated on modified plastics and polymers, focusing the attention, in the first part, on modified conducting polymers to improve sensitivity, selectivity, biocompatibility and mechanical properties, whereas the second part is dedicated to modified “environmentally friendly” polymers to improve the electrical properties. These ecofriendly polymers are divided into three main classes: bioplastics made from natural sources, biodegradable plastics made from traditional petrochemicals and eco/recycled plastics, which are made from recycled plastic materials rather than from raw petrochemicals. Finally, flexible and wearable lab-on-a-chip (LOC) biosensing devices, based on plastic supports, are also discussed. This review is timely due to the significant advances achieved over the last few years in the area of electrochemical biosensors based on modified polymers and aims to direct the readers to emerging trends in this field.Peer ReviewedPostprint (published version

Amino acids, peptides, and proteins:Implications for nanotechnological applications in biosensing and drug/gene delivery

Over various scientific fields in biochemistry, amino acids have been highlighted in research works. Protein, peptide- and amino acid-based drug delivery systems have proficiently transformed nanotechnology via immense flexibility in their features for attaching various drug molecules and biodegradable polymers. In this regard, novel nanostructures including carbon nanotubes, electrospun carbon nanofibers, gold nanoislands, and metal-based nanoparticles have been introduced as nanosensors for accurate detection of these organic compounds. These nanostructures can bind the biological receptor to the sensor surface and increase the surface area of the working electrode, significantly enhancing the biosensor performance. Interestingly, protein-based nanocarriers have also emerged as useful drug and gene delivery platforms. This is important since, despite recent advancements, there are still biological barriers and other obstacles limiting gene and drug delivery efficacy. Currently available strategies for gene therapy are not cost-effective, and they do not deliver the genetic cargo effectively to target sites. With rapid advancements in nanotechnology, novel gene delivery systems are introduced as nonviral vectors such as protein, peptide, and amino acid-based nanostructures. These nano-based delivery platforms can be tailored into functional transformation using proteins and peptides ligands based nanocarriers, usually overexpressed in the specified diseases. The purpose of this review is to shed light on traditional and nanotechnology-based methods to detect amino acids, peptides, and proteins. Furthermore, new insights into the potential of amino protein-based nanoassemblies for targeted drug delivery or gene transfer are presented

Fullerene Based Sensor and Biosensor Technologies

Sensor and biosensor technologies have shown rapid progress in recent years. These technologies use nanomaterials that have an important place in immobilization materials for recognition analyte molecules. Although fullerenes among these materials have attracted much attention in recent years, their number of studies is less than other carbon-based nanomaterials. Thanks to its completely closed structure and at least 30 double bonds, it can be modified from 30 points, which provides a great advantage. At these points, thanks to the ability to modify amine, thiol, carboxyl or metallic groups, modification residues can be created for all kinds of immobilization. According to the zero-dimensional nanomaterial class, fullerenes provide an extremely large surface area. Therefore, it provides more biological or non-biological recognition receptors immobilized on this surface area. Moreover, increasing the surface area with more recognition agent also increases the sensitivity. This is the most important parameter of sensor technologies, which is provided by fullerenes. In this book chapter, the development of fullerene-modified sensor and biosensor technologies are explained with examples, and fullerene modifications are given in figures as fullerene derivatives. Contribution was made in the method development stage by giving comparison of fullerene type sensor and biosensor systems

Cyclodextrins as Supramolecular Recognition Systems: Applications in the Fabrication of Electrochemical Sensors

Supramolecular chemistry, although focused mainly on noncovalent intermolecular and intramolecular interactions, which are considerably weaker than covalent interactions, can be employed to fabricate sensors with a remarkable affinity for a target analyte. In this review the development of cyclodextrin-based electrochemical sensors is described and discussed. Following a short introduction to the general properties of cyclodextrins and their ability to form inclusion complexes, the cyclodextrin-based sensors are introduced. This includes the combination of cyclodextrins with reduced graphene oxide, carbon nanotubes, conducting polymers, enzymes and aptamers, and electropolymerized cyclodextrin films. The applications of these materials as chiral recognition agents and biosensors and in the electrochemical detection of environmental contaminants, biomolecules and amino acids, drugs and flavonoids are reviewed and compared. Based on the papers reviewed, it is clear that cyclodextrins are promising molecular recognition agents in the creation of electrochemical sensors, chiral sensors, and biosensors. Moreover, they have been combined with a host of materials to enhance the detection of the target analytes. Nevertheless, challenges remain, including the development of more robust methods for the integration of cyclodextrins into the sensing unit

Electroanalytical point-of-care detection of gold standard and emerging cardiac biomarkers for stratification and monitoring in intensive care medicine - a review

Determination of specific cardiac biomarkers (CBs) during the diagnosis and management of adverse cardiovascular events such as acute myocardial infarction (AMI) has become commonplace in emergency department (ED), cardiology and many other ward settings. Cardiac troponins (cTnT and cTnI) and natriuretic peptides (BNP and NT-pro-BNP) are the preferred biomarkers in clinical practice for the diagnostic workup of AMI, acute coronary syndrome (ACS) and other types of myocardial ischaemia and heart failure (HF), while the roles and possible clinical applications of several other potential biomarkers continue to be evaluated and are the subject of several comprehensive reviews. The requirement for rapid, repeated testing of a small number of CBs in ED and cardiology patients has led to the development of point-of-care (PoC) technology to circumvent the need for remote and lengthy testing procedures in the hospital pathology laboratories. Electroanalytical sensing platforms have the potential to meet these requirements. This review aims firstly to reflect on the potential benefits of rapid CB testing in critically ill patients, a very distinct cohort of patients with deranged baseline levels of CBs. We summarise their source and clinical relevance and are the first to report the required analytical ranges for such technology to be of value in this patient cohort. Secondly, we review the current electrochemical approaches, including its sub-variants such as photoelectrochemical and electrochemiluminescence, for the determination of important CBs highlighting the various strategies used, namely the use of micro- and nanomaterials, to maximise the sensitivities and selectivities of such approaches. Finally, we consider the challenges that must be overcome to allow for the commercialisation of this technology and transition into intensive care medicine. Graphical abstract: [Figure not available: see fulltext.

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

Advanced Electrochemical Biosensors

With the progress of nanoscience and biotechnology, advanced electrochemical biosensors have been widely investigated for various application fields. Such electrochemical sensors are well suited to miniaturization and integration for portable devices and parallel processing chips. Therefore, advanced electrochemical biosensors can open a new era in health care, drug discovery, and environmental monitoring. This Special Issue serves the need to promote exploratory research and development on emerging electrochemical biosensor technologies while aiming to reflect on the current state of research in this emerging field

The development of molecularly imprinted polymers for sensor and colorimetric assay applications

The development of devices capable of sensing the presence or absence of molecules is a staple of the modern day world, with fields such as healthcare, forensics, agriculture and industrial processing relying upon biosensors to operate. The presented work sets focus on the use of Molecularly Imprinted Polymers (MIPs) as receptor elements in biosensing applications, demonstrating how these synthetic alternatives to traditional affinity reagents are of value. The thesis initially gives a detailed overview of the current MIP landscape, before determining areas of the field that are currently underdeveloped. The ensuing research highlights how these areas can be built upon, deploying MIPs for drug analysis and antibiotic detection. To this end, the use of MIPs in conjugation with a thermal biosensing platform is presented before shifting the research towards the use of these synthetic receptors in simple colorimetric assays designed for the rapid analysis of compounds

Polymers and Ionic Liquids

The main objective of polymer materials scientists is to develop and design high performance polymer-based materials via the introduction of block copolymers, ionomers or inorganic-organic hybrids, in order to introduce functionalities such as mechanical reinforcement, gas barrier properties, fire retardancy, shape memory behavior or self-healing ability. In the last ten years, ionic liquids have demonstrated huge potential as new components within polymer-based materials, leading to a wide range of applications. Due to their many physical-chemical properties, as well as their various possible combinations, ionic liquids represent a new path to produce multifunctional materials

SYNTHESIS, DESIGN, AND EVALUATION OF THE FLUORESCENT DETECTION OF POLYCHLORINATED BIPHENYLS(PCBs) IN AQUEOUS SYSTEM

The exposure to halogenated persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), has been linked to numerous inflammatory diseases, including diabetes, cancer and lowered immune response. PCBs have low solubility in water, and they interact with other contaminants, making their detection quite challenging. While, there have been several attempts at improving the ease of detection and sensing of PCBs, gas chromatography-mass spectrometry (GC-MS) remains the gold standard. However, despite its ubiquitous use, GC-MS is a challenging technique that requires high skill and careful sample preparation, which are time-consuming and costly. As such, there is still a need to develop a sensing system that can detect PCBs in a more efficient manner. In this work, we hypothesize that the dilute concentration of PCBs in water can be detected using a fluorescent displacement assay. To test this hypothesis, we screened a series of fluorescent molecules that were used as a fluorescence quenching pair. The displacement pair(BaP/curcumin) was evaluated in polymer microparticles (MPs) for higher sensitivity. Curcumin was immobilized to the MPs and BaP was kept free for easy displacement in the solution. MPs indicate good binding of BaP that does not come off in the solution. However, BaP displaces from the MPs in the presence of PCB. The enhanced signal of BaP indicates the presence of a novel hydrophobic interaction between BaP and PCB in water. This hydrophobic interaction leads to the successful detection of PCB. BaP fluorescence increases with trace concentrations of PCBs in water. To determine the selectivity and robustness of this response, the impact of pH, ionic strength and humic acid to mimic freshwater conditions are explored. BaP was able to detect PCBs in the micromolar range. The fluorescent dye was then immobilized on the polymer network for enhanced sensitivity and recovery. For this purpose, BaP analog pyrene is used, which behaves similar to BaP in water with PCB. This molecule was functionalized into the monomer and is polymerized into the hydrophilic polymer network for pH-based swelling, to allow PCBs within its network for the interaction with pyrene. These MPs are characterized using different techniques and their interaction with PCBs was studied