Robert Koncki

Chemical sensors and biosensors based on Prussian blues

This article is a review of the literature devoted to analytical sensors and biosensors based on Prussian blue and its analogues. Electrochemical and optical devices are characterized. Several sensing schemes and their practical analytical applications are reported. Trends and perspectives for development of Prussian blues-based (bio)sensors are indicated. The review contains 155 references.

Composite Films of Prussian Blue and N-Substituted Polypyrroles: Fabrication and Application to Optical Determination of pH

A new and simple chemical method for deposition of thin blue films composed of Prussian Blue and N-substituted polypyrroles on nonconductive supports is presented. It is found that only pyrroles which are difficult to polymerize can be used for the preparation of such films. The resulting composite films were examined by SEM-EDAX, vis-NIR, and IR spectroscopy. The films are stable, thin, homogeneous, and optically transparent. The absorption maxima are at 720 nm, and spectral changes can be monitored using semiconductor light sources and detectors. The composite films are shown to be suitable for optical determination of pH over the pH 5-9 range because their absorbance strongly depends on pH in the physiological pH range. However, they undergo irreversible spectral changes if exposed to pHs >9. The films represent an alternative to indicator-based pH sensor materials because they do not require a dye to be immobilized. The pH measurements are highly reproducible, reversible in the physiological range, and not affected by ionic strength, alkaline cations, and typical oxidants and reductants.

Enzyme biosensor for urea based on a novel pH bulk optode membrane

A new, absorbance-based enzymatic biosensor membrane for determination of urea is described. A lipophilic, fully LED- and diode laser-compatible pH sensitive dye was incorporated into a plasticized, carboxylated poly(vinyl chloride) membrane and served as the optical transducer of the sensor. Urease was covalently linked to the surface of the pH bulk optode membrane to form a very thin cover. The resulting biosensor membrane allows rapid determination of urea over the 0.3 to 100 mM range. The reproducibility, stability, and effects of pH and buffer concentration on the response of sensor are reported. The preparation of the pH transducer and the immobilization of the enzyme are simple and may easily be adopted to other biosensor types.

Creatinine biosensor based on ammonium ion selective electrode and its application in flow-injection analysis

A new, highly sensitive, fast responding and stable potentiometric biosensor for creatinine determination is developed. The biosensor is based on an ammonium ion-selective electrode. Creatinine deiminase (EC 3.5.4.21) is chemically immobilized on the surface of the polymeric ion-sensitive membrane in the form of monomolecular layer using a simple, one-step carbodiimide covalent attachment method. The resulting enzyme electrodes are useful for measurement under flow injection analysis (FIA) conditions. The biosensors exhibit excellent operational and storage stability. The enzyme electrodes retain over 70% of initial sensitivity after ten weeks of work under FIA conditions. The storage stability at 4 degrees C is longer than half a year without loss of sensitivity. Under optimized conditions near 30 samples per hour can be analyzed and the determination range (0.02-20.0mmoll(-1)) fully covers creatinine concentrations important from clinical and biomedical point of view. The simple biosensor/FIA system has been successfully used for determination of creatinine in urine, serum and posthemodialysate samples.

Disposable strip potentiometric electrodes with solvent-polymeric ion-selective membranes fabricated using screen-printing technology

A simple and reproducible method for mass production of disposable, plastic, thick-film, ion-selective electrodes using screen-printing technology is described. The properties of selective sensors for potassium, ammonium and nitrate ions obtained with this technology are shown and discussed. All the obtained strip sensors have analytical characteristics (sensitivity, selectivity, dynamic range and response time) comparable with those for conventional ion-selective electrodes. However, they practically do not require any conditioning before measurements and they respond in short time (steady-state signal is reached after a few seconds), that is important in case of the disposable sensors.

Bienzymatic potentiometric electrodes for creatine and l-arginine determination

Abstract Ammonium-selective electrodes enzymatically sensitized for creatine and l -arginine are presented. Enzyme layers of these biosensors contain two enzymes: urease and, as a second enzyme, creatinase or arginase dependent on the analyte (substrate): creatine or arginine. The bienzymatic layer with such a composition sequentially converts the analyte into ammonium ions, which are detectable by the internal sensor. Monomolecular and bimolecular bienzymatic layers immobilized directly on the ammonium sensitive membrane were used. The covalent binding of enzymes to the matrix of the ion-selective membrane made of the carboxylated poly(vinyl chloride) was performed using carbodiimide and glutaraldehyde. The extremely thin enzyme layers are strongly bound and easily penetrable. Therefore the presented biosensors are stable and respond rapidly, t 95% varies from 1.5 to 4 min. The linear ranges of both biosensors were 0.1–30 mM and the detection limits were below 10 −5 M.

Simplified paired-emitter–detector-diodes-based photometry with improved sensitivity

Paired emitter-detector diodes (PEDDs) coupled with potentiometric pH-meter or multimeter have been characterized as complete instruments for common photometric measurements as well as optical flow-through detectors. The analytical characteristics of investigated devices have been illustrated by the use of two paired red LEDs for the determination of bromothymol blue (BTB) as a model analyte. The developed devices allow rapid and sensitive BTB detection in the ppm range of concentration. Measurements with pH-meter resulted in a wide linearity of PEDD response, whereas PEDDs coupled with ordinary voltmeter offer a significant enhancement of sensitivity. Some practical applications of developed detector for the analytical and bioanalytical measurements have been indicated.

Urea sensors based on glass pH electrodes with physically immobilized urease

Abstract Different gels were used as a matrix for physical enzyme immobilization on the sensing surface o glass pH electrodes. The recommended technique of immobilization is based on enzyme entrapment within a gel prepared in situ on the glass electrode surface. Poly(vinyl chloride), cellulose trinitrate and especially cellulose triacetate are the best matrix materials of urease immobilization. The effect of buffer pH and buffer capacity and the effect of the stirring rate were investigated and the optimum measurement conditions are discussed.

Optical biosensors based on Prussian Blue films

Optical biosensing schemes based on enzymatically modified inorganic/organic transparent films predominately composed of Prussian Blue are demonstrated. The composite film, which is non-electrochemically deposited on a non-conducting support. is used as an optical transducer for flow-through biosensors based on hydrolases and oxidases. Urease and glucose oxidase are utilized as model enzymes. Action of the urea biosensor is based on optical pH sensitivity of Prussian Blue indicator. The glucose biosensor is acting as first-generation optical biosensor based on in situ generated Prussian White transducer for hydrogen peroxide. These simple, single-pass transmission optical biosensors exhibit sensitivity in the millimolar range of concentration. The biosensors are very stable owing to presence of a poly(pyrrolylbenzoic acid) network in the composite material. This organic polymer plays a dual role as a binding agent for inorganic material and as a functionalized support for strong covalent immobilization of enzyme molecules.

Composite films of Prussian blue and N-substituted polypyrroles: covalent immobilization of enzymes and application to near infrared optical biosensing

We demonstrate the feasibility of optical biosensing using a material which, in essence, is a modified inorganic film to which various enzymes were covalently attached. Thin and transparent blue films composed of Prussian blue and incorporated into a network of N-substituted polypyrroles are sensitive to pH in the 5-9 range at 720 nm wavelength and can be modified with enzymes to result in the respective biosensors. Several methods of enzyme immobilization, using bifunctional crosslinking reagents, and various enzymes were tested. The best results were obtained using the one-step carbodiimide method which resulted in highly active, stable and transparent biosensor films for optical determination of urea and acetylcholine. The operational stability exceeded 1 month and even after 2 months of dry storage at room temperature the activity did not drop. The biosensors allow optical determination of the respective substrates in the millimolar concentration range.