OPTICAL IMMUNE BIOSENSOR BASED ON SPR FOR THE DETECTION OF SALMONELLA TYPHIMURIUM

摘要

Salmonella typhimurium is one of the major pathogen dispersed through foodstuff. To avoid non-desirable effects on the health the control of foodstuff should be constant. The traditional approaches, which are used, as a rule, for the revealing of the infected organisms, are time consumable, routine and demand a special laboratory conditions with a very professional staff. For overcoming of these disadvantages there is necessary to develop instrumental methods, in particularly, based on the principles of biosensorics. The efficiency of the instrumental methods depends on many factors: technical characteristics of the registering part, specific preparation of biological sensitive layer and algorithm of fulfilled analysis. At the optimization of the general characteristics of the biosensor there is necessary to take into attention the main practice demands which concern sensitivity, specificity, rapidity, simplicity and low cost analysis. Unfortunately, in many cases, investigators involve or very expensive devices, or very complicate systems for the transducer preparation and analysis fulfilment. We used the miniature SPR based device developed by Spreta (USA) as basis of the registering part and improved it by GPS system which can provide the immediately transferring of the obtained results in the stationary laboratory for the further verification of analysis and taking of the appropriate decision to restrict of the infection source. Analysis data are transferred from device to the medical centre or the laboratory by means of radio channel. As radio-transmitter it is used the original unit, which is developed by the company "VD MAIS". The procedure of the transducer preparation included several sequential steps: a) cleaning of surface by ethanol, b) covering of surface by polyalylamine hydrochloride c) immobilization of protein A from Staphylococcus aureus and, at last, the oriented binding of the specific antibodies. The model solution of S. typhimurium with the number of concentrations (from 103 to 108 cells/mL) was prepared in 0.9% of sodium chloride. The time of the sample incubation with the transducer surface was about 5 min and after that the last was washed by the above mentioned buffer. It was stated that the sensor sensitivity was on the level 103-104 cells/mL and linear field is situated from this level up to 107 cells/mL. It is not sufficient sensitivity for all practice situations and, maybe, for its increasing there is necessary to find the most optimal variant of analysis from or/and to use the specific antibodies with high level of affinity.