Biomedical subjects

M Ozsoz

Publications and source records attributed to M Ozsoz.

3 recordsLinked to original sources

PubMed1992

A lysine dehydrogenase-based electrode for biosensing of L-lysine.

An amperometric biosensor for L-lysine based on the recently isolated enzyme lysine dehydrogenase is described. Immobilization of the enzyme onto a platinum electrode is achieved via entrapment within a gelatin support on a cellulose membrane. Anodic detection (at 0.4 V vs. Ag/AgCl) is facilitated by the presence of a redox-mediating ferricyanide ion. The effect of experimental variables such as pH, enzyme loading, applied potential, cofactor and mediator concentrations were evaluated in order to optimize the analytical performance. A detection limit of 7 x 10(-8) M, and linearity up to 7 x 10(-4) M are reported. The fast response permits adaptation for flow injection operation with good precision (RSD = 1.9%) and high sample throughout (40 samples per hour). The high specificity offered by this new enzyme is indicated by the lack of interference by other L-amino acids, alcohols or carbohydrates.

Amino Acid Oxidoreductases↗

PubMed1991

Amperometric enzyme electrode for theophylline.

An amperometric biosensor for theophylline, based on the recently isolated enzyme theophylline oxidase, is described. The enzyme is entrapped, together with a ferricytochrome C cofactor, within a polymeric (Nafion) coating. The anodic detection (at +0.4 V versus Ag-AgCl) is facilitated by the addition of a redox-mediating hexacyanoferrate(III) ion. The influence of various experimental variables is described. The limit of detection is 2 x 10(-6) mol dm-3 theophylline, with linearity prevailing up to 3 x 10(-4) mol dm-3. The fast response and wash times permit rapid flow-injection measurements, with a frequency of 180 samples h-1 and a relative standard deviation of 3.0-4.0%. Prospects of using this electrode for clinical diagnostics are discussed.

Biosensing Techniques↗

PubMed1990

Hydrophobic stripping voltammetry of antihypertensive drugs at lipid-modified electrodes.

The antihypertensive agents reserpine and rescinnamine were shown to be partitioned effectively into a lipid layer on a glassy carbon electrode. Such hydrophobic accumulation greatly enhances the sensitivity of the subsequent voltammetric scan, allowing convenient quantification of sub-micromolar concentrations. A high degree of selectivity is achieved as polar electroactive species are excluded by the hydrophobic layer. The drugs can therefore be quantified in the presence of a 100-fold amount of solution species with similar redox potentials. The response was evaluated with respect to accumulation time, concentration dependence, solution conditions, voltammetric waveform, possible interferences and other variables. Detection limits are 5 x 10(-9) M. The applicability of the method to selective measurements in untreated urine is described. The data shed new light on the sensing utility and discriminative properties of lipid electrodes.

Antihypertensive Agents↗