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Über dieses Buch

This book is intended to give technological background and practical examples, but also to give general insight into the on-going technology development in the area of biodetection. The content is therefore suitable for an array of stakeholders (decision makers, purchasing officers, etc.) and end-users of biodetection equipment within the areas of health, environment, safety and security, and military preparation. The book is divided into three sections. The first section discusses the fundamental physical and biological properties of bioaerosol's. The second section goes into more detail and discusses in-depth the most commonly used detection principles. The third section of the book is devoted to technologies that have been used in standoff applications. The last section of the book gives an overview of trends in bioaerosol detection. The reader of this book will gain knowledge about the different biodetection technologies and thus better judge their capabilities in relation to desired applications.



Introduction to Bioaerosol Detection


1. Introduction and Bioaerosol Detection Terminology

This chapter is a brief introduction to the biodetection field and provides a conceptual understanding of the capability of the current biodetection technologies. As many biodetector technologies have their origin in military applications, a very brief discussion about biological weapons is also included. Finally, the chapter addresses basic definitions and nomenclature that are used in the biodetection community.
Torbjörn Tjärnhage, Per Jonsson, Yannick Morel

2. History of the Early Biodetection Development

A serious attempt at detecting biological aerosol occurred in the late 1940s. The scientists used optical methods to detect light scatter from single 0.6 µm spore particles moving in an airstream. Considering that analogue tube electronics were the tools of the day, the achievement was remarkable. However, the technology was insufficiently sensitive to permit particle sizing at submicron range. Coincidentally, the use of Bacillus globigii (over the years the species Bacillus globigii has taxonomically changed name from Bacillus subtilis var niger and to the current Bacillus atrophaeus. However, the acronym BG is still widely used)BG aerosol as a bacterial spore simulant for anthrax was first mentioned during these studies. Decades later, other workers thought that chemiluminescence would solve the problem of detecting biological particles captured from aerosol. The technique worked perfectly under laboratory conditions but failed in real life field situations where background material caused too many false alarms. A crucial lesson learnt from this was that all detectors work perfectly in the laboratory but may fail in the field. The next evolutional step was the use of time-of-flight particle sizing technology where it was assumed that artificially generated biological agents would appear mostly in the size range greater than 2.5 µm, providing a distinguishable characteristic from background material. Still, this approach was susceptible to the occasional strong wind gusts that raise big particles from the ground with the potential to degrade false alarm reliability. A more discriminatory approach was clearly required. By good fortune, it was observed that live spores could be induced to fluoresce if excited by long wavelength UV light. A prototype instrument called the fluorescence aerodynamic particle sizer (FLAPS) was built and found to be effective in detecting the “live” simulant for anthrax in field trials. The instrument provided particle size and fluorescent brightness information which when combined with gating methods, permitted software to be developed with the potential to meet low false alarming criteria. The instrument was discovered to be sensitive enough to detect naturally occurring live bacterial particles. It has been mentioned that being “live” is a prerequisite for a particle to be infectious. Thus the potential for this instrument to detect naturally occurring infectious aerosol particles will need further verification. We also caution the tendency for non-microbiologists to misuse the term “identification” of biological agents when they actually mean segregation or sort.
Jim Ho

3. Physical and Biological Properties of Bioaerosols

Bioaerosols include bacterial cells and spores, viruses, pollen, fungi, algae, detritus, allergens and cell fragments. Bioaerosol particles are usually a small fraction of all aerosol particles in our surroundings, but their impact can be critical. They are a means for transmission of disease, they cause allergic reactions and they have effects on the global climate, ecology and biodiversity. This chapter provides an overview of the main types of bioaerosol particles, their sources, transport and sinks, and their potential effects on health and atmosphere.
Jakob Löndahl

4. Dispersion in the Atmosphere

When a bioaerosol is introduced to the atmosphere, the concentration will decrease when the aerosol is transported and diluted by wind and turbulence. Other processes, like deposition and biological decay will also act to diminish the concentration. Many important aspects of this take place in the turbulent atmospheric boundary layer i.e. basically within the lowest km the atmosphere. After a brief review of the subdivision of the atmospheric into different layers, we demonstrate by using results from a relatively simple dispersion model for the boundary layer, how different processes affect the resulting concentration. Finally we discuss the implications of sparse and highly fluctuating observed data on the meteorological modeling process. We discuss phenomenological and behavioral models, and we classify errors into model error, input data error and numerical error. We discuss the payoff between the explanatory power and the difficulties of estimating parameters for a detailed model.
Leif Persson, Lennart Thaning

5. Aerosol Sampling and Transport

The instruments described in this section aim at detecting biological particles suspended in air. This chapter describes the art and components of sampling the aerosol and transporting the particles to the actual detection unit, while keeping them airborne. Depending on the detection principle, later stages may require transferring the particles into another medium such as a liquid.
Jorma Keskinen, Marko Marjamäki

Principles and Technologies for Bioaerosol Detection


6. Light Scattering and Particle Charge Techniques for the Detection of Biological Warfare Agents

To be fully effective a biological point detection system must be capable of reliably detecting the presence of a potentially dangerous aerosol immediately it reaches the detection site. This first detection can then be succeeded by sequential analysis techniques that confirm that it is biological, deliberately generated and finally identify the agent being used.
James M. Clark

7. Bioaerosol Detection with Fluorescence Spectroscopy

A brief introduction to the fundamental theory of fluorescence spectroscopy applied to bioaerosol detection is given and developed systems are described. Bioaerosol detection relies on the fact that many relevant microorganisms contain molecules such as aromatic amino acids and reduced nicotinamide adenine dinucleotide (NADH) with characteristic fluorescence when excited by ultraviolet (UV) radiation. Several bioaerosol detection systems based on fluorescence have been developed and tested during the last two decades. They have proven to be very sensitive with a short response time. The main drawback of fluorescence is the relatively low specificity. There are ways to increase the classification capability by utilizing multiple wavelengths, spectral and temporal detection of the emission. Some of the design considerations are presented, including choices of excitation sources and detectors. This chapter is concluded with an outlook for the future.
Per Jonsson, Fredrik Kullander

8. Bioaerosol Detection with Atomic Emission Spectroscopy

Techniques based on atomic emission spectroscopy (AES), as flame emission spectroscopy (FES), or laser-induced plasma spectroscopy (LIBS), could be of interest for fast detection and classification of biological warfare agents (BWA). Bioagents can be directly investigated in real time by these techniques, without sample preparation in ambient atmosphere. Complex interactions between an energetic flame or a thermal plasma and the bioaerosol compounds provide spectral signals that are characteristic of the particle elementary composition. Detectors require sampling system, reactor (flame or plasma), optical sensors, and reliable data processing. The challenge is to develop sensitive tools to detect low BWA concentrations within a natural and complex atmospheric background. Firstly, FES is described in general terms with emphasis put on flame transformation processes. Representative and experimental FES applications are illustrated. Then, LIBS technique is presented with elementary limits of detection, and complex plasma–particle interactions. Differences between FES and LIBS are discussed, as well as possible complementary use. Potential technical improvements are suggested for both techniques to further enhance the bioaerosol detection.
Nicolas Leone, Damien Descroix, Salam Mohammed

9. Mass Spectrometry Techniques in the Analysis of Bioaerosols: Development and Advancement

Bioaerosols are airborne particles that may contain pathogenic species that can cause serious risks to various government and public sectors. The major health concern due to bioaerosols is that certain communicable diseases are transmitted through airborne particles, including viruses, bacteria, and fungi. Biological warfare agents can be disseminated as bioaerosol particles and could pose severe safety issues for military operations as well as serious economic and health concerns to the public. Thus, it is imperative to develop and implement real-time detection and accurate identification technologies for the monitoring of bioaerosols. Mass spectrometry (MS) techniques have been developed and improved in their sensitivity, fieldability, and compatibility to bioaerosol analysis and characterization in real-time settings. MS techniques have shown promise in the real-time analysis of bioaerosols. An overview of bioaerosol MS is presented for general perspectives on its application for detection and identification capabilities. Also, the capabilities of MS techniques and the nature of their output and impact on the detection and identification of bioaerosols will be discussed. Exploration of the advantages and drawbacks of the applications for different MS techniques in the analysis of bioaerosols is addressed.
Rabih E. Jabbour, Samir V. Deshpande, A. Peter Snyder, Mary M. Wade

10. Detection of Bioaerosols Using Raman Spectroscopy

This chapter contains a brief historical perspective and basic principles of the Raman Effect, focusing on its evolution from an esoteric technique to an everyday lab tool used for sample analysis. As a vibrational spectroscopic technique, Raman is complementary to infrared spectroscopy (IRS) and some fundamental differences, as well as similarities between them are discussed. Raman spectroscopy has been established as an excellent tool for both materials characterization and biophysical studies. The type of information obtained from this technique, several applications in detection, identification and characterization of several types of samples are also discussed. Within the main principal applications of Raman spectroscopy and its variations, including Normal Raman, resonance Raman and UV-Raman spectroscopies, coherent anti-stokes Raman scattering and surface enhanced Raman scattering, this chapter focuses on detection of biological aerosols. This topic was reviewed in depth and details are included. Optimization parameters to achieve fast, nondestructive and sensitive analysis on biodetection and to analyze the data are also included briefly to allow the fundamental studies for applications in research areas such as environmental pollution monitoring, biomedicine and in areas of defense and security.
Hilsamar Félix-Rivera, Samuel P. Hernández-Rivera

11. Biological Detection with Terahertz Spectroscopy

This chapter describes the basic principles of resolved vibrational spectroscopy of biological macromolecules and species in the sub-terahertz spectral range of radiation and the application of this technology for the biological detection including material in air. The origin of THz spectroscopic signatures specific to bioparticles is based upon low energy internal molecular vibrations that absorb radiation at characteristic frequencies. The multiple resonance features provide distinctive spectral fingerprints for detection and identification of harmful biological species. The sensitivity and selectivity of THz biosensing is demonstrated. The possibility to make THz detector systems for the biological detection is discussed.
Tatiana Globus, Boris Gelmont

Standoff Sensor Systems for Bioaerosol Detection


12. Introduction to Stand-Off Detection of Biological Warfare Agents

This chapter gives a short one page introduction to stand-off detection of biological warfare agents. Since only a couple of the available technologies for stand-off detection are presented in this book, the introduction mentions other technologies as well.
Per Jonsson, Göran Olofsson

13. Spectrally Resolved Laser-Induced Fluorescence Lidar Based Standoff Biodetection System

Over the years, rapidly monitoring wide areas for the presence of threatening bioaerosols has become an important objective for defense and public security. This chapter describes an important contending technology showing valuable capability to achieve that goal: Spectrally resolved laser-induced fluorescence lidars. After an introduction to this subject, the fundamental lidar theory associated with this specific technology is derived. Then, the robustness, specificity, and sensitivity of this technique to recognize the class of bioaerosols from a remote position are discussed. Subsequently, a statistical multivariate method based on the Mahalanobis distance to classify bioaerosols from their collected fluorescence induced spectral data is detailed. Finally, a conclusion reviews the key issues associated with this inelastic lidar technology as an important component of a complete threatening bioaerosol defense suite.
Jean-Robert Simard, Sylvie Buteau, Pierre Lahaie

14. Standoff Aerosol Size Determination based on Multiple-Field-Of-View of Elastic Scattering

Multiple-Field-Of-View (MFOV) lidar can be used to characterize the size and optical depth of low concentration bioaerosol clouds. The concept relies on the measurement of the forward scattered light by using the background aerosols at various distances at the back of a sub-visible cloud. It also relies on the subtraction of the background aerosol forward scattering contribution and on partial attenuation of the first order backscattering using a low transmission mask. The validity of the concept developed to retrieve with a good precision the effective diameter and the optical depth of low concentration bioaerosol clouds is illustrated using simulation results and experimental MFOV lidar measurements. Calculations are also done to show that the method presented can be extending to small optical depth clouds retrieval.
Gilles Roy, Nathalie Roy

Outlook and Challenges


15. Trends in Biological Detection

This chapter shortly summarizes some highlights from the development of modern biodetectors and looks forward in what directions the development is going. The initial expectations may have settled to a more realistic level and biodetectors are now finding their role in different military and security applications. Also biodetectors originally developed for military or security applications are being used in different environmental, medical, industrial and pure scientific applications. Comparison of different detector characteristics and their functioning in a certain application have become more important and methods to test and evaluate biodetectors are now under harmonization and standardization.
Per Jonsson, Torbjörn Tjärnhage


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