Rapid investigation on fresh human whole blood by means of Raman and SERS techniques

The time-consuming processes of some clinical biochemical analysis approaches call forfaster, ideally real time techniques of early analytes identification in body fluids (e.g. whole blood). Blood analysis provides important clinical information in diagnostic procedure and is frequently performed in physicians practise. There is a great interest in optical measurement that would permit rapid and simultaneous analysis of multiple analytes in fresh whole blood without the need of conventional reagents and sample processing, such as centrifuging and saline buffer (PBS). As optical method, Raman spectroscopy has considerable promise as a diagnostics and analytical tool in medicine [1,2]. We have been interested in Raman studies of fresh whole blood, partly because Raman spectroscopy may be useful for clinical laboratory and rapid reagentless real time blood analysis, and partly because hemoglobin (Hb) and carotenoids identification could be crucial to study several pathologies (e.g. thalassemia, renal function regulation, antioxidant role in cancer and asthmatic pathologies). Moreover analysis of oxygenation of Hb and production of NO-, CO-, and met-Hb may be useful for monitoring pathological and/or functional changes in a human body [3-4]. Significant additional advantages in blood molecules analysis arise using the surface enhanced Raman spectroscopy (SERS) yielding a signal enhancement of 4- 15 orders of magnitude compared with normal Raman spectroscopy due to the employment of noble metal nanoparticles [5]. The purpose of the present study is to measure and analyze Raman spectra of freshly acquired human whole blood to systematically compare the observed features with existing spectroscopic data. Raman spectra collected with 514nm excitation have evidenced bands attributed to carotenoids, while SERS spectra have shown an increased sensibility to hemoglobin.