http://mdpi.com/journal/sensors/special_issues/conductive_polymers/ This special issue is intended to focus on the recent advances that are being made in all areas of conducting polymer based electrochemical sensors. It is devised to survey the application of various kinds of conducting polymer, such as π-conjugated conducting polymer, inorganic conducting polymer, and conducting polymer composites as electrode modifier, as structural elements, as transducer, and as sensor component in electrochemical sensors. Special emphasis will be placed on the nano-structured conducting polymer based electrochemical biosensors, immunosensors, DNA sensors, and modified electrodes for electroanalysis. It features all aspects of amperometric, potentiometric, conductometric, coulometric, impedimetric, and voltammetric sensors and biosensors. New modification/combination of electrochemical detection principle, integrated and hyphenated with sampling, fluidic handling, separation with conducting polymer based sensors are also included. Full research papers with new results (experimental or theoretical) in this field or a comprehensive review of the state- of-art of cantilever sensors are encouraged for submission. There are no length restrictions for the manuscripts. http://mdpi.com/1424-8220/8/12/8423/ Most of the current techniques for in vivo detection of dopamine exploit the ease of oxidation of this compound. The major problem during the detection is the presence of a high concentration of ascorbic acid that is oxidized at nearly the same potential as dopamine on bare electrodes. Furthermore, the oxidation product of dopamine reacts with ascorbic acid present in samples and regenerates dopamine again, which severely limits the accuracy of the detection. Meanwhile, the product could also form a melanin-like insulating film on the electrode surface, which decreases the sensitivity of the electrode. Various surface modifications on the electrode, new materials for making the electrodes, and new electrochemical techniques have been exploited to solve these problems. Recently we developed a new electrochemical detection method that did not rely on direct oxidation of dopamine on electrodes, which may naturally solve these problems. This approach takes advantage of the high performance of our newly developed poly(anilineboronic acid)/carbon nanotube composite and the excellent permselectivity of the ion-exchange polymer Nafion. The high affinity binding of dopamine to the boronic acid groups of the polymer affects the electrochemical properties of the polyaniline backbone, which act as the basis for the transduction mechanism of this non-oxidative dopamine sensor. The unique reduction capability and high conductivity of single-stranded DNA functionalized single-walled carbon nanotubes greatly improved the electrochemical activity of the polymer in a physiologically-relevant buffer, and the large surface area of the carbon nanotubes increased the density of the boronic acid receptors. The high sensitivity and selectivity of the sensor show excellent promise toward molecular diagnosis of Parkinson's disease. In this review, we will focus on the discussion of this novel detection approach, the new interferences in this detection approach, and how to eliminate these interferences toward in vivo and in vitro detection of the neurotransmitter dopamine. http://mdpi.com/1424-8220/8/12/8423/ Thu, 18 Dec 2008 00:00:00 CET Sensors 2008-12-18 8 12 Review 8423 8452 1424-8220 A Nonoxidative Electrochemical Sensor Based on a Self-Doped Polyaniline/Carbon Nanotube Composite for Sensitive and Selective Detection of the Neurotransmitter Dopamine: A Review 2008-12-18 doi: 10.3390/s8128423 Shah R. Ali Rishi R. Parajuli Yetunde Balogun Yufeng Ma Huixin He http://mdpi.com/1424-8220/8/4/2331/ Many research studies have been conducted on the use of conjugated polymers in the construction of chemical sensors including potentiometric, conductometric and amperometric sensors or biosensors over the last decade. The induction of conductivity on conjugated polymers by treating them with suitable oxidizing agents won Heeger, MacDiarmid and Shirakawa the 2000 Nobel Prize in Chemistry. Common conjugated polymers are poly(acetylene)s, poly(pyrrole)s, poly(thiophene)s, poly(terthiophene)s, poly(aniline)s, poly(fluorine)s, poly(3-alkylthiophene)s, polytetrathiafulvalenes, polynapthalenes, poly(p-phenylene sulfide), poly(p-phenylenevinylene)s, poly(3,4-ethylenedioxythiophene), polyparaphenylene, polyazulene, polyparaphenylene sulfide, polycarbazole and polydiaminonaphthalene. More than 60 sensors for inorganic cations and anions with different characteristics based on conducting polymers have been reported. There have also been reports on the application of non-conducting polymers (nCPs), i.e. PVC, in the construction of potentiometric membrane sensors for determination of more than 60 inorganic cations and anions. However, the leakage of ionophores from the membranes based on these polymers leads to relatively lower life times. In this article, we try to give an overview of Solid-Contact ISE (SCISE), Single-Piece ISE (SPISE), Conducting Polymer (CP)-Based, and also non-conducting polymer PVC-based ISEs for various ions which their difference is in the way of the polymer used with selective membrane. In SCISEs and SPISEs, the plasticized PVC containing the ionophore and ionic additives govern the selectivity behavior of the electrode and the conducting polymer is responsible of ion-to-electron transducer. However, in CPISEs, the conducting polymer layer is doped with a suitable ionophore which enhances the ion selectivity of the CP while its redox response has to be suppressed. http://mdpi.com/1424-8220/8/4/2331/ Thu, 03 Apr 2008 00:00:00 CEST Sensors 2008-04-03 8 4 Review 2331 2412 1424-8220 Developments in the Field of Conducting and Non-conducting Polymer Based Potentiometric Membrane Sensors for Ions Over the Past Decade 2008-04-03 doi: 10.3390/s8042331 Farnoush Faridbod Parviz Norouzi Rassoul Dinarvand Mohammad Reza Ganjali http://mdpi.com/1424-8220/8/2/594/ This report presents an optimization of potentiometric measurements withcitrate-selective electropolymerized poly(neutral red) electrodes. The optimal backgroundelectrolyte for these measurements is a TRIS buffer with nitrate at pH 8.5. The electrodesdescribed here exhibit stable and reproducible near-Nernstian response to citrates with alow detection limit of 6 × 10-6 M. Electrodes polymerized from sulfuric acid andacetonitrile are compared in detail. Simple and sensitive method for quantification ofcitrate in real-life samples by potentiometry with poly(neutral red) electrodes arepresented. Data from potentiometric measurements of citrate are compared with capillaryelectrophoresis. http://mdpi.com/1424-8220/8/2/594/ Mon, 04 Feb 2008 00:00:00 CET Sensors 2008-02-04 8 2 Article 594 606 1424-8220 Optimalization of Poly(neutral red) Coated-wire Electrode for Determination of Citrate in Soft Drinks 2008-02-04 doi: 10.3390/s8020594 Gabriela Broncová Tatiana V. Shishkanova Martin Krondak Radko Volf Vladimír Král http://mdpi.com/1424-8220/8/1/118/ Organic conjugated polymers (conducting polymers) have emerged as potentialcandidates for electrochemical sensors. Due to their straightforward preparation methods,unique properties, and stability in air, conducting polymers have been applied to energystorage, electrochemical devices, memory devices, chemical sensors, and electrocatalysts.Conducting polymers are also known to be compatible with biological molecules in aneutral aqueous solution. Thus, these are extensively used in the fabrication of accurate,fast, and inexpensive devices, such as biosensors and chemical sensors in the medicaldiagnostic laboratories. Conducting polymer-based electrochemical sensors and biosensorsplay an important role in the improvement of public health and environment because rapiddetection, high sensitivity, small size, and specificity are achievable for environmentalmonitoring and clinical diagnostics. In this review, we summarized the recent advances inconducting polymer-based electrochemical sensors, which covers chemical sensors(potentiometric, voltammetric, amperometric) and biosensors (enzyme based biosensors,immunosensors, DNA sensors). http://mdpi.com/1424-8220/8/1/118/ Wed, 09 Jan 2008 00:00:00 CET Sensors 2008-01-09 8 1 Review 118 141 1424-8220 Electrochemical Sensors Based on Organic Conjugated Polymers 2008-01-09 doi: 10.3390/s8010118 Md. Aminur Rahman Pankaj Kumar Deog-Su Park Yoon-Bo Shim http://mdpi.com/1424-8220/7/12/3272/ The construction and general performance characteristics of two novelpotentiometric membrane sensors responsive to the acebutolol are described. Thesensors are based on the use of ion-association complexes of acebutolol (AC) withtetraphenylborate(TPB) (I) and phosphomolybdate(PM) (II) as exchange sites in a PVCmatrix. The sensors show a fast, stable and near- Nernstian for the mono charge cationof AC over the concentration range 1×10-3 - ~10-6 M at 25 °C over the pH range 2.0 -6.0 with cationic slope of 51.5 ± 0.5 and 53.0 ± 0.5 per concentration decade for AC-Iand AC-II sensors respectively. The lower detection limit is 6×10-6 M and 4×0-6 M withthe response time 20-30 s in the same order of both sensors. Selectivity coefficients ofAC related to a number of interfering cation and some organic compounds wereinvestigated. There are negligible interferences are caused by most of the investigatedspecies. The direct determination of 3 - 370 μg/ml of AC shows an average recovery of 99.4 and 99.5% and a mean relative standard deviation of 1 . 5 % at 100.0 μg/ml forsensor I and II respectively. The results obtained by determination of AC in tablets usingthe proposed sensors which comparable favorably with those obtained by the Britishpharmacopoeia method. In the present investigation the electrodes have been utilized asend point indicator for some precipitation titration reactions. http://mdpi.com/1424-8220/7/12/3272/ Thu, 13 Dec 2007 00:00:00 CET Sensors 2007-12-13 7 12 Article 3272 3286 1424-8220 PVC Membrane Sensors for Potentiometric Determination of Acebutolol 2007-12-13 doi: 10.3390/s7123272 Gamal Abdel-Hafiz Mostafa Mohamed Mahmoud Hefnawy Abdulrahman Al-Majed http://mdpi.com/1424-8220/7/12/3258/ The detection of the carcinogenic trihalomethanes (THM) in public water supplysystems using low-cost equipment has become an essential feature, since these compoundsmay be generated as by-products of water-treatment processes. Here we report on a sensorarray that extends the concept of an “electronic tongue” to detect small amounts ofbromoform, bromodichloromethane and dibromochloromethane, with detection limits aslow as 0.02 mg L-1. The sensor array was made up of 10 sensing units, in whichnanostructured films of conducting and natural polymers were deposited onto goldinterdigitated electrodes. The principle of detection was impedance spectroscopy, withmeasurements carried out in the range between 1 Hz to 1 MHz. Using data at 1 kHz, atwhich the electrical response varied considerably by changing the analyte, we demonstratedwith principal component analysis (PCA) that samples with the 3 brominatedtrihalomethanes can be distinguished from each other and for various concentrations. http://mdpi.com/1424-8220/7/12/3258/ Wed, 12 Dec 2007 00:00:00 CET Sensors 2007-12-12 7 12 Article 3258 3271 1424-8220 Detection of Brominated By-Products Using a Sensor Array Based on Nanostructured Thin Films of Conducting Polymers 2007-12-12 doi: 10.3390/s7123258 Eduarda Regina Carvalho Nelson Consolin Filho Everaldo Carlos Venancio Osvaldo N. O. Luiz H. C. Mattoso Ladislau Martin-Neto http://mdpi.com/1424-8220/7/8/1655/ Diureidocalix[4]arene have been applied as new ionophore in liquid membraneelectrode (ISE) sensitive towards un-dissociated benzoic acid. The electrode demonstratedresponse towards benzoic acid with the detection limit 2.0 x 10-4 M which is sufficient forthe determination of benzoic acid added to beverages as preservative in milimolarconcentration. The selectivity coefficients measured by the matched potential method(MPM) showed its good selectivity against common anions present in drink samples. Allmeasurements were made in presence of 1.0 x 10-2 M NaHSO4 pH 3.0 in order to reducethe influence of OH-. The applicability of diureidocalix[4]arene incorporated ISE has beenchecked by recovery test of benzoic acid in the presence of artificial drink matrix and bystandard addition method. http://mdpi.com/1424-8220/7/8/1655/ Mon, 27 Aug 2007 00:00:00 CEST Sensors 2007-08-27 7 8 Article 1655 1666 1424-8220 Potentiometric Responses of Ion-Selective Electrodes Doped with Diureidocalix[4]arene towards Un-dissociated Benzoic Acid 2007-08-27 doi: 10.3390/s7081655 Agnieszka Krajewska Pavel Lhotak Hanna Radecka