Fourier-transform mid-infrared (FT-MIR) spectroscopy is a powerful
technique that probes intramolecular vibrations of almost any molecule, enabling the
acquisition of metabolic fingerprint of cells, tissues and biofluids (e.g. serum, urine and
saliva, etc.), in a rapid (in minutes), simple (without or with minimum sample
processing), economic (without consumption of reagents), label-free and highly
sensitive and specific mode. Due to the flexibility of the technique, there are diverse
modes of spectra acquisition, from classical transmission and transflection, to highthroughput
measurements using micro-plates in transmission mode, to fiber optic
probes coupled to Attenuated Total Reflection (ATR) detection, enabling in situ
analysis, throughout micro-spectroscopy, with spatial resolution, enabling detection of
residual analytes and imaging at the sub-cellular level. Due to the composition
complexity of biological samples, the mid-infrared spectra are usually very difficult to
interpret without the application of complex and sophisticated mathematical and
statistical analysis routines, such as: spectra pre-processing methods to minimize noise
and other non-informative data that compromise subsequent pattern recognition
models; deconvolution methods to resolve overlapped spectral bands; methods to
decrease data dimension and features extraction; supervised and non-supervised pattern
recognition methods as those based on support vector machines and artificial neural
networks. The present work reviews the main acquisition modes, pre-processing and
multivariate spectral analysis used in FT-MIR spectroscopy, followed by the
application of FT-MIR for the diagnosis of a multitude of diseases. FT-MIR
spectroscopy constitutes one of the most promising biophysical techniques for
analyzing biological samples, and consequently may be used for diseases prognosis,
diagnosis and even for personalized treatment.
Keywords: Biomedical sciences, FT-MIR spectroscopy, Medical diagnosis, MIR
spectroscopy.
