Infrared spectroscopy of a single cell--the human erythrocyte

Methods for obtaining the infrared spectrum of a single erythrocyte by infrared microscopy have been developed. The spectrum contains the amide I, II, and III bands characteristic of protein secondary structure near 1650, 1550, and 1300 cm-1, respectively. Bound carbon monoxide exhibits a readily measured band at 1951 cm-1 for 12C16O and 1907 cm-1 for 13C16O. Both amide and CO bands are similar to those found for purified hemoglobin A. Spectra can be obtained in H2O or D2O media under physiologically relevant conditions. Single cell infrared spectroscopy (SCIR) permits the qualitative and quantitative determination of differences among individual red cells. These results suggest many potential applications for SCIR for the measurements of properties of individual cells at the molecular level under physiologically relevant conditions.