Use of the monodisperse Pt/Ni@rGO nanocomposite synthesized by ultrasonic hydroxide assisted reduction method in electrochemical nonenzymatic glucose detection.

An electrochemical non-enzymatic sensor was developed for the detection of glucose based on an electrode modified with monodisperse platinum-nickel nanocomposites-decorated on reduced graphene oxide (Pt/Ni@rGO) which was synthesized using a new ultrasonic hydroxide assisted reduction method. Because the nanocomposites prepared by using NaOH (OH- ligands) are much smaller nanocomposites on the supports compared to the ones without OH- ligands. Such a monodisperse Pt/Ni@rGO nanocomposites-based electrode exhibited a high electrochemical activity for electrocatalytic oxidation of glucose in alkaline solution. Amperometric analysis showed a glucose sensitivity of 171.92 µA/mM cm2 of, the detection limit of 6.3 µM and a linear range of 0.02-5.0 mM glucose concentration. Fabricated sensor platform demonstrated long-term stability and good reproducibility, in addition to high selectivity.

Copolymer based multifunctional conducting polymer film for fluorescence sensing of glucose.

A simple, rapid and effective fluorescence sensing platform has been fabricated using a fluorescent conducting polymer surface. For this purpose, a rhodamine based electroactive monomer (RDC) and a functional group containing monomer (SNS) have been copolymerized to develop a conducting polymer based sensor platform having a fluorescence and enzyme-binding surface on ITO electrode. The proposed fluorescence sensing mechanism for detection of glucose is related to the consumption of dissolved oxygen at the double layer of the electrode which is fluorescence quenching agent by glucose-GOx reaction. Concentration of glucose was investigated quantitatively from 0.05 to 1 mM via fluorescence signal measurement. This novel approach could be adapted for the production of various rapid and effective fluorescence sensing platforms for glucose.

Rhodamine-based conjugated polymers: potentiometric, colorimetric and voltammetric sensing of mercury ions in aqueous medium.

Herein, we report the synthesis and characterization of a new rhodamine-based monomer (RD-CZ), and an investigation of the optical and electrochemical properties of the corresponding polymer (P(RD-CZ)), which was electropolymerized on an ITO electrode. The resulting P(RD-CZ) polymer film was used as a simple and novel multi-signal sensor platform, which demonstrates ion-selective potentiometric, colorimetric and voltammetric responses in aqueous media for the first time. P(RD-CZ) exhibits excellent selectivity for Hg2+ ions compared with Cd2+, Cu2+ Zn2+, and Fe3+ using the potentiometric technique, which depends on the increasing charge carrier transport through rhodamine-bound Hg2+ with a limit of detection (LOD) of 9.77 × 10-8 M. The P(RD-CZ) polymer film also exhibits a distinct color change from orange to purple, which is detectable even by the naked eye, in the presence of Hg2+ ions. The LOD for Hg2+ ions obtained using the colorimetric method is 3.16 × 10-8 M. The same material has also been used for the voltammetric sensing of Hg2+ in aqueous media with a detection limit of 1 × 10-7 M. In this study, a conductive polymer-based sensor platform for detecting mercury ions via three different methods has been designed for the first time. By doing so, a disposable planar paper-based ion-sensing platform, which is suitable for low-cost point-of-care and in-field testing applications, could be fabricated with a highly reproducible and linear response towards different concentrations of analyte ions in aqueous and biological samples.

Rhodamine functionalized conducting polymers for dual intention: electrochemical sensing and fluorescence imaging of cells.

We report here the electrochemical co-polymerization of two functional monomers, one containing fluorescent rhodamine dye (RF) and the other monomer having amine groups (RD), onto electroactive Indium Tin Oxide (ITO) glass. After one step preparation of these surfaces, a three peptide called ArginylGlysylAspartic acid (RGD) was immobilized via EDC chemistry by using amine groups (P(RF-co-RD)/RGD) of the co-polymer, for further use in various bio-applications such as cell adhesion and imaging as well as electrochemical cell sensing. The resultant RGD bound and also fluorescent platforms were utilized as targeted adhesion materials towards integrin avb3 receptor positive (U87-MG) cells and the selectivity was checked by using HaCaT cells as a control. Finally, electrochemical measurements were carried out to characterize step by step surface modification and detection of cell attachment. As a result, P(RF-co-RD)/RGD is a promising material for multi-purpose uses, such as fluorescence imaging without the need for an additional dye for cell visualization and as a targeted adhesion and electrochemical cell sensing platform.

Smart windows application of carbazole and triazine based star shaped architecture.

A novel triazine-based, star shape and electroactive monomer, 2,4,6-tris(2-(9H-carbazol-9-yl)ethoxy)-1,3,5-triazine (TCZ) which contains 2,4,6-trichloro-1,3,5-triazine as the core and 2-(9H-carbazol-9-yl)ethanol as the arms, was successfully synthesized. After electrochemical polymerization of the TCZ monomer, called PTCZ, the polymer shows superior optoelectronic and thermal properties due to its unique three-dimensional shape and highly-branched structure in comparison with linear analogues. Electrochromic studies exhibited that PTCZ has turquoise color in the oxidized state and is transparent in the neutral state. Due to the fact that the redox color characteristics of PTCZ are indispensable for smart windows, a PTCZ-based electrochromic device was formed with PEDOT as complementary coloring material. A potential range of -1.5 to +1.8 V was determined to be suitable for operating the PTCZ/PEDOT device between transparent and blue colors. Characterizations of the device were performed in term of switching times, optical contrast, optical memory and redox stability.

Ferrocene-functionalized 4-(2,5-Di(thiophen-2-yl)-1H-pyrrol-1-yl)aniline: a novel design in conducting polymer-based electrochemical biosensors.

Herein, we report a novel ferrocenyldithiophosphonate functional conducting polymer and its use as an immobilization matrix in amperometric biosensor applications. Initially, 4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)amidoferrocenyldithiophosphonate was synthesized and copolymerized with 4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)benzenamine at graphite electrodes. The amino groups on the polymer were utilized for covalent attachment of the enzyme glucose oxidase. Besides, ferrocene on the backbone was used as a redox mediator during the electrochemical measurements. Prior to the analytical characterization, optimization studies were carried out. The changes in current signals at +0.45 V were proportional to glucose concentration from 0.5 to 5.0 mM. Finally, the resulting biosensor was applied for glucose analysis in real samples and the data were compared with the spectrophotometric Trinder method.