Abstract: An amperometric immunosensor based on a recombinant nucleocapsid antigen has been developed for fast determination of antibodies against Sin Nombre (SN) virus in human blood serum. This approach combines the advantages of utilization of highly dispersed immunosorbent, with highly sensitive electrochemical detection of enzyme-marker, and flow injection scheme of immunoassay. A main benefit of recombinant nucleocapsid antigen is that antigen preparation and standardization is easy. The complete immunoassay can be performed in 24 minutes. The short overall assay time could be a major advantage in the field of diagnostic screening of infectious diseases in mobile laboratories and small hospitals. The immunosensor has been successfully used in the determination of anti-Hantavirus IgG in human blood plasma and is easily adaptable for the detection of other types of viral infections.

Abstract: Current practices for preventing microbial diseases rely upon careful control of various kinds of pathogenic bacteria in food safety and environmental monitoring. The main disadvantages of conventional bacterial detection methods are the multistep procedure and long time requirements. This article gives an overview of alternative electrochemical biosensors for detection of pathogenic bacteria in the food industry. Focus has been on new microbial metabolism-based antibody-based and DNA-based biosensors. The underlying principles and applications of these biosensors are discussed. Recent developments in flow injection biosensor systems with an electrochemical detection are also presented.

Abstract: This paper presents an overview of different physicochemical instrumental techniques for direct and indirect identification of bacteria such as: infrared and fluorescence spectroscopy, flow cytometry, chromatography and chemiluminescence techniques as a basis for biosensor construction. A discussion of publications dealing with emerging biosensors for bacterial detection is presented. The review presents recent advances in the development of alternative enzyme-and immunosensors for detection of pathogenic bacteria in a variety of fields (e.g. clinical diagnostics, food analysis and environmental monitoring). Depending on the biological element employed: enzyme; nucleic acid and antibody based biosensors are discussed. Depending on the basic transducer principles, recent advances in biosensing technologies that use electrochemical, piezoelectric, optical, acoustic and thermal biosensors for detection of pathogenic bacteria are overviewed. Special attention is paid to methods for improving the analytical parameters of biosensors including sensitivity and analysis time as well as automation of assay procedures. Recent developments in immunofiltration, flow injection and flow-through biosensors for bacterial detection are overviewed from the systems engineering point of view. Future directions for biosensor development and problems related to the commercialization of bacterial biosensors are discussed in the final part of this review.

Abstract: A flow injection amperometric immunofiltration assay system for the rapid detection of total Escherichia coli and Salmonella was developed. The system is based on the use of disposable porous nylon membranes which act as a support for the immobilization of anti-E. coli or anti-Salmonella antibodies. The assay system consists of a flow injection system, a disposable filter-membrane and an amperometric sensor. Parameters affecting the performance of the immunofiltration assay system such as membrane pore size, non-specific binding, conjugate concentration and sample volume were studied and optimized. A sandwich scheme of immunoassay was employed and the immunofiltration system was able to specifically and directly detect 50 cells/ml of total E. coli or 50 cells/ml of Salmonella with an overall analysis time of 35 min. This immunosensor can be easily adapted for the assay of other microorganisms and may be a basis for a new class of highly sensitive and automated bioanalytical devices for the rapid quantitative detection of bacteria.