Physics And Chemistry Basis Of Biotechnology - De Cuyper - tiera.ru

Philippe Lahorte and Wim Mondelaers
thorough understanding is only brought about as the result of the combined use of
several techniques which thus requires an interdisciplinary approach.
The current chapter represents the second half of our overview. It consists of three
major parts. First of all a survey is given of the experimental techniques and theoretical
methods currently available for studying the effects of radiation on biological systems
from the physical to the biological stage. In a second part we will elaborate on some
important techniques (electron paramagnetic resonance spectroscopy and quantum
chemical calculations) with which direct information concerning identity and structure
can be obtained of the radicals involved in processes in the chemical stage. Also an
overview will be given of the fundamental research in this field. This approach is partly
inspired by our own research efforts in which the determination of radical identity and
structure is often either a goal in itself or a necessary hurdle that has to be taken in the
development of new applications. The final part will be devoted to technological
aspects of the irradiation process. In specific, the basic principles of accelerator
technologies will be elucidated and an overview will be given of the applicationoriented
irradiation research in biology and related fields such as biomedical and
environmental engineering, food technology, medicine and pharmacy. Radiation
research in the field of radiotherapy will not be treated as this is beyond the scope of
the present review.
The target audience of this contribution being bio(techno)logical scientists, an
attempt was made to describe technologies and methods from a qualitative point of
view, focusing on conveying the overall ideas and limitations, and the biologic
relevance of the data and information that can be obtained from them. For further
exploration and a deeper understanding the reader will be referred to literature citations
and reference works.
2. Experimental and theoretical methods for studying the effects of radiation
Figure 1 gives an overview of the broad spectrum of experimental and theoretical tools
for studying physical, physico-chemical, chemical or biological aspects of the effects of
radiation exposure on biological systems. Obviously, the delineation of the scope and
the field of activity of each method is somehow subjective. The classification as shown
in Fig. 1 is therefore to be interpreted as indicative rather then exactly corresponding to
the boundaries of the four stages of interaction which eventually exist only by virtue of
human intellect. In this section we will briefly discuss the experimental techniques and
theoretical methods, available for the combined physical and physico-chemical stages,
and the biological stage. The techniques for studying radicals in the chemical stage will
be discussed in more detail in paragraph 3.
As has been extensively discussed in the first part of this overview the physical and
physico-chemical stages on the time-scales of radiation effects are characterised by a
distribution of the radiation energy among the irradiated specimen. Along the path of
the primary ionising species, radicals and electrons are formed in tracks. In most
environments these intermediates are highly reactive and, hence, can exist only for very
short periods. In this case, these transient species diffuse into the medium and give rise
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