Penicillin sensor

Penicillins are the world s most important antibiotics, the production per year being worth 25 million. The quantitation of penicillin is required for control of the fermentative production of penicillin G and penicillin V and their splitting to 6-aminopenicillic acid (6-APA). 6-APA is the basic material for semisynthetic penicillins. 

These reactions are coupled with a signal transducer using mainly the pH decrease and the reaction enthalpy. Whereas (3-lactamase has been combined with various transducer types, penicillin amidase has been applied only in one enzyme electrode for penicillin (Table 9). 

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FIGURE 6-20 Configuration of a penicillin sensor based on an microarray electrode coated with a pH-responsive polypyrrole. Vq = gate voltage VD = drain voltage ID = drain current PS = potentiostat CE and RE = counter and reference electrodes, respectively. (Reproduced with permission from reference 76.)... 

A. Poghossian, M. Thust, M. Schoning, M. Muller-Veggian, P. Kordos and H. Luth, Cross-sensitivity of a capacitive penicillin sensor combined with a diffusion barrier, Sens. Actuators B Chem., 68(1) (2000) 260-265. 

To realize glucose-, urea- and penicillin sensors in a flow injection mode (FIA) appropriate enzymes can be immobilized [13]. The measuring range is very limited in all reported cases due to enzyme kinetics and a more sophisticated set up is required. 

Potentiometric penicillin sensors are mainly based on glass electrodes working with free enzyme or with enzyme included in an electrode cover. In the first penicillin electrode, (5-lactamase was directly photopolymer-ized in acrylamide on the electrode (Papariello et al., 1973). Enfors and Nilsson (1979) designed a sterilizable penicillin sensor where a solution containing (5-lactamase was pumped into a reaction chamber in front of a flat glass electrode, after sterilization of the electrode (Fig. 75). 

Yerian, T. D., Christian, G. D., Ruzicka, J., Flow Injection Analysis as a Diagnostic Tool for Development and Ibsting of a Penicillin Sensor , J. Anal. Chem. 60 (1988) 1250-1256. 

Several methods for enzyme immobilization can be found in literature. In our laboratory, we have developed a new enzyme immobilization technique making possible response time of the biosensor much inferior to any of the response times so far reported for a penicillin sensor the combined pH electrode to be coated with the enzyme was left... 

Fig. 3 Calibration curve for the penicillin sensor as a function of sample injection volumes (50,250,5(X) iL)...

Nishizawa, M.. Matsue, T., and Uchida, I., Penicillin sensor based on a microarray electrode coated with pH-responsive polypyrrole, Atud. Chem., 64. 2462 (1992). 

A. Poghossian, T. Yoshinobu, A. Simonis, H. Ecken, H. Liith and M.J. Schoning, Penicillin detection by means of field-effect based sensors EnFET, capacitive EIS sensor or LAPS Sens. Actuators B 78, 237-242 (2001). 

Besides, potentiometric sensors with ion-selective ionophores in modified poly(vinyl chloride) (PVC) have been used to detect analytes from human serum [128], Cellular respiration and acidification due to the activity of the cells has been measured with CMOS ISFETS [129], Some potentiometric methods employ gas-sensing electrodes for NH3 (for deaminase reactions) and C02 (for decarboxylase reactions). Ion-selective electrodes have also been used to quantitate penicillin, since the penicillinase reaction may be mediated with I or GST. 

An example of the use of soft sensors is given by the automation of a penicillin production dependent on strict adherence to certain hmits in the fermentation process since such biological systems are sensitive to changes in operational conditions. An important issue in the use of soft sensors is what to do if one or more of the input variables are not available due, for example, to sensor failure or maintenance needs. Under such circumstances, one must rely on multivariate models to reconstruct or infer the missing sensor variable. ... 

M.J. Arauzo-Bravo, J.M. Cano-Izquierdo, E. Gomez-Sanchez, M.J. Lopez-Nieto, Y.A. Dimitraidis and J. Lopez-Coronado, Automatization of a penicillin production process with soft sensors and an adaptive controller based on neuro fuzzy systems. Control Eng. Pract., 12, 1073-1090 (2004). 

Urea in kidney dialysate can be determined by immobilizing urease (via silylation or with glutaraldehyde as binder) on commercially available acid-base cellulose pads the process has to be modified slightly in order not to alter the dye contained in the pads [57]. The stopped-flow technique assures the required sensitivity for the enzymatic reaction, which takes 30-60 s. Synchronization of the peristaltic pumps PI and P2 in the valveless impulse-response flow injection manifold depicted in Fig. 5.19.B by means of a timer enables kinetic measurements [62]. Following a comprehensive study of the effect of hydrodynamic and (bio)chemical variables, the sensor was optimized for monitoring urea in real biological samples. A similar system was used for the determination of penicillin by penicillinase-catalysed hydrolysis. The enzyme was immobilized on acid-base cellulose strips via bovine serum albumin similarly as in enzyme electrodes [63], even though the above-described procedure would have been equally effective. 

By controlling the structural and electronic properties of sNPS which are related to the nanocrystallite dimensions and porosity, their surface selectivity and sensitivity to different gases (nitrogen and carbon oxide, vapors of water and organic substances) can be adjusted. This approach for the effective detection of acetone, methanol and water vapor in air was described in [13-15].The minimal detectable acetone concentration was reported to be 12 pg/mL. Silicon sensors for detection of SO2 and some medicines such as penicillin were created [16-18]. sNPS were used for the development of a number of immune biosensors, particularly using the photoluminescence detection. Earlier we developed similar immune biosensors for the control of the myoglobin level in blood and for monitoring of bacterial proteins in air [19-23]. 

The fits in this case are not as good as the ones obtained for the penicillin case (Figs. 2.10 and 2.11). This is due to the fact that the glucose oxidation mechanism is not yet completely understood and the kinetic equations are only approximate. Nevertheless, it is again possible to plot the profiles of the most important species in the gel layer and from this fit to estimate the optimum thickness of the gel layer (Fig. 2.17). For the glucose sensor, the optimum thickness appears to be 150pm,... 

A new development in the field of potentiometric enzyme sensors came in the 1980s from the work of Caras and Janata (72). They describe a penicillin-responsive device which consists of a pH-sensitive, ion-selective field effect transistor (ISFET) and an enzyme-immobilized ISFET (ENFET). Determining urea with ISFETs covered with immobilized urease is also possible (73). Current research is focused on the construction and characterization of ENFETs (27,73). Although ISFETs have several interesting features, the need to compensate for variations in the pH and buffering capacity of the sample is a serious hurdle for the rapid development of ENFETs. For detailed information on the principles and applications of ENFETs, the reader is referred to several recent reviews (27, 74) and Chapter 8. 

Low-pressure flow injection interfaces have been used as links between the extractor and either a photometric detector [118], a flow-through potentiometric sensor [119] or a piezoelectric sensor [120] in dynamic flow injection (FI) systems. Figure 7.18 depicts these unusual types of interface. In the first (Fig. 7.18A), a membrane phase separator (total fluid volume 50 pi) was used to remove CO, from the extract. In this way, interferences were suppressed while ensuring quantitative transfer of the solutes (viz. chloramphenicol and penicillin G) to the hydrodynamic system. 

Fuh et al. (1988) devised an enzyme optrode for penicillin. (5-Lactamase was immobilized on a fluorescein isothiocyanate-labeled porous glass particle which was glued to the tip of a fiber optic bundle. Excitation was carried out by an argon laser. pH changes resulting from the enzyme reaction led to changes of the fluorescence intensity. The response time of the sensor was 20-45 s, the detection limit being 0.1 mmol/1 penicillin. 

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