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

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

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

Fabrication and applications of dopamine-sensitive electrode

The neurotransmitter dopamine has shown to be of central importance to difference brain functions, such as movement, reward, and addiction. A biosensor for the detection of dopamine in the brain should have a fast time response to monitor concentration changes which happen on a subsecond time scale. Furthermore, the sensor should have a high sensitivity to dopamine, because the physiological concentrations of dopamine were found to be in the range form nanomolar to lower micromolar. High selectivity is also necessary to distinguish the desired signal from electrochemical interferences in the brain such as ascorbic acid. Fast scan cyclic voltammetry at glass-encased carbon fiber microelectrodes has been shown to fulfill these requirements and is therefore often used for measurements of easily oxidizable neurotransmitters like dopamine. In this dissertation, some drawbacks of the technique and the sensor are addressed and improved. Chapter 1 contains an overview of electrochemical methods that have been used to detect various neurotransmitters in the brain. Chapter 2 explains a method to increase the sensitivity and selectivity for dopamine of carbon fiber microelectrodes by covalent attachment of a cation-exchange layer to the electrode surface. A method utilizing tungsten microwires as substrate for the construction of flexible gold, platinum, and carbon microelectrodes is described in Chapter 3 and 4. Carbon-coated tungsten microwires have then been examined for use as in vivo dopamine sensor. The microwires showed the same electrochemical properties as conventional glass-encased carbon fiber microelectrodes. In chapters 5 and 6 a novel instrumental method to subtract of the large background current, which occurs during application of fast scan rates, is presented. This method has then been used to examine the changes in this background current and account for these changes. This enabled us to expand the time course for fast scan voltammetric measurements 20-fold. Furthermore, the origin of these background changes was examined. In the last chapter tungsten based microelectrodes were used to evaluate changes in dopamine concentrations and pH of the extracellular fluid in a primate brain during reward delivery