Applications of Synchrotron Radiation: Micro Beams in Cell Micro Biology and Medicine : Ari Ide-Ektessabi , Springer, New York, 2007. $159.00 (218 pp.). ISBN 978-3-540-46424-2
In the past few years, developments in hard x-ray microprobe instrumentation and methods have improved our understanding of the role trace metals play in life and in causing disease. The results have led to considerable interest from researchers in the life sciences who want to use microprobe instruments with high spatial resolution and trace-level sensitivity. Nonetheless, the literature is missing a comprehensive book that focuses on the biological and medical applications of such devices and could also serve as a reference for interested scientists and students. Although Applications of Synchrotron Radiation: Micro Beams in Cell Micro Biology and Medicine by Ari Ide-Ektessabi, a professor at Kyoto University’s International Innovation Center in Japan, covers some of its material well, it does not succeed in filling the gap.
The book is split into two parts. In the first, the author offers brief coverage of synchrotron radiation, x-ray fluorescence (XRF), x-ray spectroscopy, detector basics, and beamline layouts. In the second, he discusses biomedical applications, from the structurally straightforward analysis of single cells to the more complex analysis of tissue sections. The book’s subtitle is broad and may be misleading to some readers because the text’s contents are, perhaps necessarily, more narrow. The author limits his scope to a discussion of hard XRF microscopy and microspectroscopy. He omits such areas as soft x-ray microbeams, microbeam irradiation, and microdiffraction, which is a good choice because it would be difficult for him to cover those diverse areas comprehensively, but it still may disappoint some readers.
Applications of Synchrotron Radiation , unfortunately, covers its subject matter unevenly. The author focuses on experiments and instrumentation with which he has experience, and he uses that experience to provide some well-detailed experimental descriptions. However, several critical technologies and developments either have been omitted or are mentioned only in passing. For example, Ide-Ektessabi does a good job describing the approaches used to analyze XRF spectra, but he does not cover x-ray focusing optics, even though the technique has relevance in the generation of microbeams and has been critical in propelling x-ray microscopy forward. His topic selectivity continues into the discussions of experimental details in that he does not present the broad range of options and necessary considerations for both sample preparation and experimental configuration. For instance, an adequate discussion of artifacts associated with chemical fixation is absent, despite the fact that the preparation technique is used almost exclusively throughout the described experiments. Cryogenic techniques to probe frozen hydrated samples, and thus avoid fixation artifacts, or to investigate freeze-dried samples are not mentioned at all.
Moreover, a number of comments in the book are incorrect, and some are severely misleading. For example, the author repeatedly states that x-ray microprobe analysis is nondestructive. While in some cases radiation damage may not become apparent, that statement is not true for biological samples in general. In particular, radiation damage must be taken into account in microspectroscopy.
The descriptions of the biomedical applications are the best part of the book, and the author’s hands-on expertise does make a difference. The applications, such as to metals in embryonic stem cell differentiation or in neurodegenerative diseases, are most interesting and relevant, and the procedures and approaches are explained well. Yet Ide-Ektessabi sometimes makes sweeping conclusions drawn from what seem to be limited data sets; at other times he leaves the reader perplexed by presenting observations without interpretation. That part of the book is also hampered by the somewhat dated nature of the featured experiments and instrumentation, a particularly unfortunate oversight in a rapidly evolving field. For instance, today’s instruments can resolve intracellular distributions of metals and other elements on the level of individual organelles—well below what is depicted in the book. That spatial resolution clearly has a major impact on the types of biological applications that are possible.
The biological and biomedical applications of x-ray microprobe analysis represent a growing, vibrant area of research in which new instrumentation and applications are constantly being developed. For a detailed discussion of technical aspects of XRF, albeit one not focused on biomedical applications or on microprobes, interested readers can consult the Handbook of Practical X-Ray Fluorescence Analysis (Springer, 2006), edited by Burkhard Beckhoff and colleagues. For a glimpse at the numerous studies being carried out, readers need only turn to one of several recent reviews on the subject matter, such as Christoph J. Fahrni’s article, “Biological Applications of X-Ray Fluorescence Microscopy: Exploring the Subcellular Topography and Speciation of Transition Metals,” in the April 2007 issue of Current Opinion in Chemical Biology.
Unfortunately, as much as interested scientists and graduate students may long for a comprehensive book on the applications of synchrotron radiation, they may have to wait a little longer.
