SCP of Live Cells in Aqueous Environment

Although the high water background absorption degraded the S/N ratio of the measurement, the use of the PapMap method, including NA-PCA (see Sections S.2.3.2 and 5.2.4.1, respectively), allowed for the collection of excellent spectra of live cells and the effects of chemicals perturbing these cells. Furthermore, we could demonstrate that cells could be kept alive for at least 24 h, and that starvation of the cells by changing the medium to a buffer solution caused cell death in a relatively short time [68, 69]. 

Aside from the fixation studies, which were carried out for both exfoliated and cultured cells, the majority of the work presented in the sections above has dealt with exfoliated cells that is, it reported a truly new form of cytology, namely SCP. To the best of our knowledge, work on exfoliated cells at the cell-by-cell level is now being carried out exclusively at the LSpD, and the size of the data sets at the LSpD far exceeds all previously collected data sets combined [35,44]. At the time of writing this summary, it appears that the SCP has matured to a level that allows for detection of cellular abnormalities, such as dysplasia, cancer, and viral infection in exfoliated cells and, thus, is poised to be applied to areas where classical cytology has very poor performance, in many cases below 50% accuracy. 

The reason that the progress in SCP has been somewhat slower than that in other areas of spectral diagnostics is the fact that the correlation between classical cytopathology and SCP is difficult. In SCP, one has to rely on luck that within an ensemble of cells scrutinized by SCP there is a diagnosable, abnormal cell. After a few thousands of cells from dysplastic patients, however, it will become very likely that some cells are found that display abnormal spectra and can, indeed, be 

In this review, aspects of IR spectroscopy for medical diagnostics have been presented. There are major differences between this new field and classical spectroscopy of biomolecules due to the size and complexity of the systems, but it is important to point out that this work is based on, and relies on, decades of research in biospectroscopy. Yet there are two major differences between classical biospectroscopy and the medical apphcations first, there is a heavy reliance on mathematical methods for data analysis, since multivariate methods of analysis are highly suitable for extracting small, correlated spectral differences that are often smaller than and are buried in uncorrelated spectral variations. Second, and even more important, is the fact that for medical apphcations, conclusions can never be based on single measurements, since the variability of the sample is enormous, both on a patient-to-patient and on a ceU-to-cell level. Thus, the authors hope that this research not only advances the field of medical diagnostics by spectral methods but also helps to usher in new ways to look and process spectral data. 

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