This review discusses current development in biosensors for the detection of biological warfare agents (B WAs). BWAs include bacteria, virus and toxins that are added deliberately into air, water and food to spread terrorism and cause disease or death. The rapid and unambiguous detection and identification of B WAs with early warning signals for detecting possible biological attack is a major challenge for government agencies particularly military and health. The detection devices --biosensors--can be classified (according to their physicochemical transducers) into four types:. electrochemical, nucleic acid, optical and piezoelectric. Advantages and limitations of biosensors are discussed in this review followed by an assessment of the current state of development of different types of biosensors. The research and development in biosensors for biological warfare agent detection is of great interest for the public as well as for governments.
Keywords: biological warfare agents, biosensors, electrochemical biosensors, piezoelectric sensors, optical biosensors.
A biosensor is an analytical device which converts a biological response into an electrical signal. Bioterrorism is the use of viruses, bacteria, other organisms, or toxins derived from living organisms as a biological weapon to cause death or disease in a civilian population. A biological weapon may ultimately prove more powerful than a conventional chemical weapon because its effects can be far-reaching and uncontrollable. A number of pathogenic bacteria can be considered as possible biological warfare agents. Highly dangerous bacteria include Clostridium botulinum, Francisella tularensis, Salmonella typhimurium and Yersinia pestis (1-3). Other bioagents, such as Venezuelan equine encephalitis, Marburg, Ebola and influenza viruses are of lesser importance despite the fact that infections with these viruses are serious and mortality is relatively high, but due to the difficulty in their preparation, their position on the list of biological warfare agents (BWA) is lower (4,5). In 1979, after an accident involving B. anthracis in the Soviet Union, doctors reported civilians dying of anthrax pneumonia (i. e., inhalation anthrax). Death from anthrax pneumonia is usually swift. The bacilli multiply rapidly and produce a toxin that causes breathing to stop. While antibiotics can combat this bacillus, supplies adequate to meet the treatment needs following an attack on a large urban population would need to be delivered and distributed within 24 to 48 hours of exposure. The National Pharmaceutical Stockpile Program (NPS) is designed to enable such a response to a bioterrorist attack. In comparison with chemical warfare agents (CWA), BWA production is much cheaper, and terrorist or military attack with BWA is more effective both in the range of the hazardous area and in the number of expected casualties. The infectious dose (ID) (amount of organism needed for infection outbreak) is different for each agent. Usually the intake of aerosol (particles 1-10 [micro]m) by the lung is able to cause disease with a lower ID for the given BWA (6).
A biosensor is made up of a biorecognition molecule immobilised over a signal transducer to give a reagent-less analytical device. The biorecognition molecule, such as an enzyme, antibody, sequence of DNA, peptide or even a microorganism, makes the biosensor very selective so that the molecule of interest can be picked out by the biosensor from a matrix of many other molecules (7,8). The signal transducer determines the extent of the biorecognition event and converts it into an electronic signal which can be output to the end user by an alarm.
An enzyme-based electrochemical transducer has also been reported for the detection of biological warfare agents (5). Enzyme-based biosensor diagnostic methods for the detection of biological weapons are preferred over other systems because of their selectivity, sensitivity and greater accuracy. …