IMPROVED FIBER OPTIC CHEMICAL SENSOR FOR PENICILLIN

An optical penicillin biosensor is described, based on the enzyme peni cillinase. The sensor is fabricated by selective photodeposition of an alyte-sensitive polymer matrices on optical imaging fibers. The penici llin-sensitive matrices are fabricated by immobilizing the enzyme as m icrometer-sized particles in a polymer hydrogel with a covalently boun d pH indicator. An array of penicillin-sensitive and pH-sensitive matr ices are fabricated on the same fiber. This array allows for the simul taneous, independent measurement of pH and penicillin. Independent mea surement of the two analytes allows penicillin to be quantitated in th e presence of a concurrent pH change. An analysis was conducted of enz yme kinetic parameters in order to model the penicillin response of th e sensor at all pH values. This analysis accounts for the varying acti vity of the immobilized penicillinase at different pH values. The sens or detects penicillin in the range 0.25-10.0 mM in the pH range 6.2-7. 5. The sensor was used to quantify penicillin concentration produced d uring a Penicillium chrysogenum fermentation.