| Penicillin is a number of beta-lactam family. It has a broad spectrum of antibacterial activity and commonly used for prophylactic or therapeutic purpose in veterinary medicine. The presence of penicillin residues in food of animal origin (milk, meat) has a serious influence on health of the public and trade of imports and exports. The residues of veterinary medicine mean that the animal products contain not only the drug but also its metabolite. Because of the extensive hypersensitivity reaction to the consumers, the detection of penicillin is very important. Electrochemical biosensors have been the most burgeoning and one of the most flourish research realms in the electrochemistry and electroanalytic chemistry. They have been widely applied in many cases such as life science, environmental science, analytic science, and material science. Because of the merits of speediness, high sensitivity, specificity and economy, electrochemical biosensors could be an alternative to commonly used assays. In this paper, Penicillinase and bacilluscereus are immobilized by different methods on different electrodes to construct microbiosensors and enzyme biosensors. At last penicillin is detected in phosphatic buffer solution (PBS) and milk with the current or potential as responsive signals.The main contents of this paper include five parts:Part one expatiates the national standard methods and limit to control standard of the determination of penicillin residues in milk products. The states, problems, and possible soluble approach of existing methods are mentioned too.Part two summarizes the work principles and the preparing methods of electrochemical biosensors. The perspective of penicillin determination with electrochemical biosensors is also discussed.Part three introduces the electrochemical principles and methods for penicillin quantitative detection, including mainly Cyclic Voltanunetry, Chronoamperometry and Electrochemical alternating Impedance.In the fourth part, Penicillinase and bacilluscereus are immobilized by glutaraldehyde-bovine serum albumin and sodium alginate. The membranes are placed in the vicinity of a flat pH electrode using a nylon net, thus constituting two kinds ofpenicillin electrochemical biosensors based on the detection of changes in pH. The sensors are used to detect penicillin residues in milk, under the condition of low concentration. The results show that the penicillinase biosensor made by crossing-linked is better than the one made by embedded and the microbial sensor in linear relationship, response time and detection limits.In the fifth part, Penicillinase, hematein and nano gold colloid are immobilized by glutaraldehyde-bovine serum albumin. The membranes are modified on different electrode to construct amperometric electrochemical biosensors for the determination of trace penicillin in milk. The response signal is well improved by the nano gold colloid. The detection limit is 2.81 ×10(-5) mmol ? L-1 obtained in PBS and 5.61 X10-4 mmol ? L-1 obtained in milk. To characterize the interactions of enzymes with nano gold colloide and hematein, electrochemical impedance spectroscopy(EIS) is used. The result shows that the detection limit of the biosensor made by Pt electrode has been fell 10 times as against the one made by Au electrode, and fell 50 times as against the one made by flat pH electrode. So the amperometric electrochemical biosensors made by Pt electrode isvery promising for the penicillin residues detection. |
