Aziz Paşahan

Synthesis, Characterization of a New Organosoluble Polyimide and Its Application in Development of Glucose Biosensor

A new aromatic organosoluble polyimide was synthesized from the 4,4′-Diaminodiphenileethane with 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) via a conventional two-stage process. This polymer showed good solubilities in N-methyl-2-pyrrolidone and m-cresol. The polyimide was characterized by FT-IR, GPC, TGA, DSC and DTA, with intrinsic viscosity and adhesive properties also being evaluated. Then, glucose oxidase (GOD) enzyme was immobilized into aromatic organosoluble polyimide by two different methods. It was demonstrated that the poly[4,4′-Diamina very promising substrate for the immobilization and stabilization of enzymes and the development of highly stable biosensors.

Poly[tris((p-aminophenoxy)phosphineoxide)-3,3′,4,4′-benzophenonetetracarboxylicdiimide] as a New Polymeric Membrane for the Fabrication of an Amperometric Glucose Sensor

Poly[tris((p-aminophenoxy)phosphineoxide)-3,3′,4,4′-benzophenonetetracarboxylicdiimide] (PAB) was used as an immobilized enzyme membrane for the fabrication of an amperometric glucose sensor. Enzyme immobilization was performed by two different methods and structural morphology of immobilized enzyme membrane was studied by SEM. The amperometric response of the sensor to hydrogen peroxide, formed as the product of the enzymatic reaction, was measured at a potential of 0.7 V in phosphate buffer solution by means of the TB technique. The influence of preparation conditions (polyimide film thickness, enzyme amount) on electrode performance was examined to obtain the optimal experimental parameters. Sensor characteristics (pH, response time, selectivity, stability) of the PAB/GOx/Pt electrode prepared under optimal conditions has been investigated. Results showed that this sensor exhibited a linear range up to 6 mM and a response time of about 60 s. with good stability. When glucose was injected into the PBS solution in the presence of fouling substances (lactose, sucrose, and urea), excellent amperometric responses were observed. Also, it was seen that the PAB/GOx-Pt electrode blocked the signal current of electroactive oxalic acid.

Maltose-Containing Polyurethane Films: Synthesis, Characterization, and Their Use for Determination of Dopamine in the Presence of the Electroactive and Nonelectroactive Interferents

A series of polyurethanes were prepared from the maltose-ethylene glycol-diphenylmethane diisocyanate and used to construct a novel polyurethane electrode for the detection of dopamine. The polyurethanes were characterized by FT-IR, differential scanning calorimetry, and thermogravimetric analysis. The intrinsic viscosity and adhesive properties were also evaluated. Selectivity behaviour of films prepared from polyurethane solutions containing 1%, 3%, 5%, and 10% maltose to electroactive and nonelectroactive substances was examined by DPV. The results demonstrated that polymer electrode by 2 µL polyurethane solutions containing 3% maltose was allowed penetration of dopamine while blocking the permeation of ascorbic acid and uric acid through film.

Electropolymerized Polytyramine Film for the Selective Determination of Uric Acid

Electropolymerized polytyramine film was proposed for determination of uric acid in the presence of ascorbic acid. The influence of electropolymerization conditions on performance of the polytyramine film was examined to obtain the optimal experimental parameters. The voltammetric results demonstrated that polytyramine film obtained at the optimized conditions allowed penetration of large amounts of uric acid while blocking the permeation of electroactive (ascorbic acid, cysteine and oxalic acid) and non-electroactive interferents (lactose, sucrose and urea) through film in PBS. Therefore, it has been claimed that the polymeric film could be used as uric acid-selective membrane over a broad range of interference.

Poly (3-aminophenol) Film as a Uric Acid-Selective Electrode

In order to prepare uric acid-selective polymeric membrane in the presence of electroactive (ascorbic acid, cysteine, oxalic acid) and nonelectroactive (lactose, sucrose and urea) substances, poly (3-aminophenol) films were prepared by means of electropolymerization on Pt electrodes. By systematically investigating the influence of polymerization conditions on sensor performance of the poly (3-aminophenol) film, the optimal parameters were determined. The voltammetric results showed that polymeric films obtained at the optimized conditions were allowed penetration of large amounts of uric acid (UA) while rejecting ascorbic acid, cysteine and oxalic acid in PBS. Therefore, it has been claimed that the polymeric films could be used as uric acid-selective membrane.

Synthesis, characterization of poly(4, 4’-diaminophenylethanepyromellitimide) and its use as immobilized enzyme polyimide membrane

A novel polyimide prepared from pyromellitic dianhydride (PMDA) and 1,2-bis(4-aminophenyl)ethane was characterized by Fourier transform infrared spectrometer and gel permeation chromatography. Thermal properties of the poly(4,4’-diaminophenylethane-pyromellitimide) (PDP) were evaluated by differential scanning calorimetry, differential thermal analysis and thermogravimetry. The PDP exhibited high decomposition temperature Td (°C), good thermal stability and good adhesive properties. Moreover, that the possibility of whether the chemically-prepared polyimide film could be used as a membrane for immobilization of glucose oxidase (GOx) was investigated. The amperometric response of the PDP/GOx/Pt electrode to hydrogen peroxide, formed as the product of enzymatic reaction, was measured at a potential of 700 mV (vs. SCE) in phosphate buffer solution by means of the TB technique. The amperometric glucose sensor was very high R-value (0.9995). The structure of the GOx micelles contained in polyimide membrane was observed by scanning electron microscopy. From the amperometric responses, it was also demonstrated that PDP film could be used as a solid-state immobilized enzyme polyimide membrane for biosensor design because of its strong adherence to electrode surface and chemical stability.

Preparation and properties of selective polyurethane films and their use for the development of biomedical dopamine sensor

ABSTRACT Polyurethane films were synthesized by 3,4-divanillyltetrahydrofuran and different diisocyanates. These prepared polyurethanes were characterized by FT-IR, DSC, DTA, and TGA techniques. For the amperometric applications, synthesized polyurethanes exhibited suitable Tg (°C), good thermal stability and good adhesive properties. In addition, because of their interesting film properties, attempts were made to prepare dopamine-sensing electrode. For this reason, selectivity of film-coated electrodes obtained from the chemically prepared polyurethanes toward electroactive and nonelectroactive species were examined by means of DPV technique. From the electrochemical results obtained, it has been demonstrated that the PU-1-coated electrode can be used for the development of biomedical sensor. GRAPHICAL ABSTRACT

A novel electrochemical biosensor based on polyimide-boron nitride composite membranes

ABSTRACT Polyimide (PI) and polyimide-boron nitride (PI-BN) composites as dopamine-selective membrane were synthesized. The structures of the monomer, pure PI, and PI-BN composites were characterized by FT-IR, SEM, and thermal analysis techniques. Experiment results showed that introduction of BN particles increased porosity, selectivity and improved heat-resistance of polyimide matrix. Selectivity of PI-BN composite membranes toward dopamine and interferences was examined by DPV technique. Electrochemical measurement results illustrated that polyimide membrane containing 5%BN possessed wide linear ranges, excellent sensitivity, selectivity, reversibility, and low detection limits (4 × 10−8 M). The polyimide membrane was very high R value (0.9904). GRAPHICAL ABSTRACT

Amperometric Simultaneous Measurement of Copper and Cobalt Ions with Polythiophene Incorporating Pendant Terpyridine Groups

Terpyridine containing thiophene monomer was synthesized. Electrochemical behavior of the monomer was studied by cyclic voltammetry. This monomer was polymerized via electrochemical methods and the resultant polymer was characterized. The stepwise fabrication process of the polymeric film electrode and its electrochemical sensing performance towards simultaneously Co and Cu ions were evaluated. The sensing parameters of the polymer electrode were investigated in detail, and the determination conditions were optimized. Under the optimal conditions, sensor response peak is linear to the Co ion concentration in the range of 1.0-50.0 µM and the Cu ion concentration in the range of 1.0–20.0 µM. Detection limit of terpyridine-based polythiophene film electrode for Co and Cu is respectively 100 nM and 0.05 nM.

Synthesis, characterization of pyridine-based polyimides and their use as glucose oxidase immobilization media

Abstract A novel diamine monomer, containing 2,6-diaminopyridine, bis-pdimethylaminophenyl- 2,6-pyridine (S26DAP), was prepared from 4- (dimethylamino)benzaldehyde and 2,6-diaminopyridine. The monomer was characterized by FT-IR, NMR and elemental analyzer. The monomer was then utilized to prepare polyimides with dianhydrides such as pyromellitic dianhydride (PMDA), 3,3’,4,4’-benzophenonetetracarboxylic dianhyride (BPDA), 4,4’- oxydiphthalic anhydride (ODPA) and 3,3’,4,4’-biphenyltetracarboxylic dianhydride (BTDA) by the one-step method; synthesis of polyimides, followed by thermal imidization. The polyimides were characterized by FT-IR, GPC with intrinsic viscosity and adhesive properties also being evaluated. The polyimides exhibited high Tg (°C) (186-209 °C), good thermal stability and good adhesive properties. Medium to high molecular weight polymers were attained, with inherent viscosities near or higher than 1.05-1.32 dL/g, the solubility in dipolar aprotic solvents of the polyimides were much better than that of the aromatic polyimides. Furthermore, chemically synthesized polyimides were used for immobilization of glucose oxidase (GOx). The amperometric responses of the prepared GOx-polyimide-coated electrodes to glucose were examined at a potential of 0.7 V in PBS solution by means of TB technique. The results show that polyimide (S26DAP-PI-4) can be used for immobilization of glucose oxidase.