Polymer immobilized enzyme optrodes for the detection of penicillin

Abstract

The preparation and performance of two enzymebased fiber-optic sensors (optrodes) capable of detecting penicillin are described. Each sensor consists of a polymer membrane that is covalently attached to the tip of a glass optical fiber. The membrane contains the enzyme peniclilnase and a pHsensitive fluorescent dye. A signal Is produced when the enzyme catalyzes the cleavage of the &lactam ring of penicillin to produce penicilloic acid and, consequently, a pH change in the microenvironmmt of the membrane. The sensors differ in the way the polymer membrane is constructed and in the type of pH indicator dye used. Both optrodes exhibit response times (40-60 8 ) significantly lower than those of the corresponding enzyme electrodes (2 min). Each gives a linear response over the concentration range of 0.000 25 to 0.01 M penicillin 0, when measured in a 0.005 M phosphate butler. The data indicate that these ImmoMilzation strategies produce similar results and may be considered complementary alternatives in future enzyme optrode appiications.

Galvanostatic Entrapment of Penicillinase into Polytyramine Films and its Utilization for the Potentiometric Determination of Penicillin

“…Two main factors that can influence the sensitivity of potentiometric detection with biosensors are buffer concentration and pH of the measurement solution [29]. Due to the use of PNCnase for fabrication of the penicillin biosensor, the required pH was fixed at 7 to ensure optimum enzymatic activity [34].…”

“…Both of these effects contributed to the reduction of the potentiometric response as observed in this study. This observation highlights the need to balance the achievement of sensitive potentiometric measurement against the necessity to control the buffering capacity of measurement solution [29]. …”

Fabrication of a Single Layer and Bilayer Potentiometric Biosensors for Penicillin by Galvanostatic Entrapment of Penicillinase into Polypyrrole Films

“…A number of methods have been used to immobilise P’nase to develop penicillin biosensors. These have included covalent binding 10, 11 self‐assembled immobilisation 12, 13 physical adsorption 14, 15 and entrapment 16. Nishizawa et al.…”

Enzyme-Based Fiber Optic Sensors

“…Penicillin is detected using the reaction: penicillin > penicilloate + H+ (1) penicillinase Glucose is measured by its conversion to gluconic acid according to:…”

“…I). 1 The fluorescein is covalently attached to the polymer backbone according to a procedure that was developed for a pH optrode. 2 Measurements were made using a portable fiber optic fluorimeter described previously.…”