Real-time analysis of blood in vivo injected with nitroglycerin using Raman spectroscopy

Raman spectra of blood in arteries of nude mice injected with nitroglycerin is analyzed in real-time and noninvasively. The Raman spectrum of blood in artery is captured every 10 s. Analysis results show that the spectra of the blood mainly have these characteristic peaks: 1548, 1618, 1654 cm-1 (protein) and 1125 cm-1 (blood sugar). Raman spectral intensity decreases from 280 s to 730 s after the injection of nitroglycerin, which shows that the blood concentration becomes diluted. This may be due to the expansion of blood vessels. The characteristic peak intensities before and after nitroglycerin injection change as below: the 1548 cm-1 peak intensity decreases from 1965.42 to 1273.61, by 35.2%; the peak 1125 cm-1 intensity decreases from 411.59 to 223.79, by 46.63%. This means that the contents of protein and sugar in blood decrease, namely, hemoglobin in the blood of nude mice denatures, and blood sngar levels significantly decrease. The Raman spectrum analysis in real-time in vivo can provide new technologies and methods for the study of the metabolic mechanism of nitroglycerin.