Investigation of Spermatozoa and Seminal Plasma by Fourier Transform Infrared Spectroscopy

Abstract

Fourier transform infrared (FT-IR) spectra of human spermatozoa and seminal plasma were recorded and analyzed. The procedure that was established for sample preparation enabled acquisition of reproducible spectra. The parameter I₁₀₈₇/I₉₆₆ for controlling spectra reproducibility was defined. The assignment of bands was carried out using an empirical approach and the origin of the “sperm specific doublet”, the bands at 968 cm⁻¹ and 981 cm⁻¹, was determined. The principal component regression (PCR) algorithm was used to define the specific spectral regions correlating to characteristics of spermatozoa, such as concentration, straight-line velocity (VSL), and beat cross frequency (BCF). Then, simple spectral parameters, such as band intensities and band ratios, were tested to determine which one best correlates to characteristics of spermatozoa. The region of the amide I band, between 1700 cm⁻¹ and 1590 cm⁻¹, was defined as a specific spectral region that correlates to the concentration of spermatozoa. The parameter that gave the linear dependence to the concentration of spermatozoa was the intensity of the amide I band. For VSL, the bands between 1119 cm⁻¹ and 943 cm⁻¹ were defined as the specific spectral region. The relative amount of nucleic acids with respect to proteins showed linear dependence on the straight-line velocity of spermatozoa. BCF showed the best correlation to the bands between 3678 cm⁻¹ and 2749 cm⁻¹, which largely represent lipids and proteins. These results suggest that FT-IR spectroscopy can serve as an adjunct to conventional histopathology studies.