Infrared Spectroscopy in Molecular Study of the Piezoelectric Effect in Pig's Shin Bone

Despite growing number of literature demonstrating the piezoelectric effect in bones at macro level there's still a lack of papers describing this effect at molecular level.In order to examine this effect more specifically, a study has been conducted to show the possibility of using infrared spectroscopy on samples contained in the electric field.This is the first known research on applying infrared spectroscopy to study the influence of electric field and compressive stress on bones' structure represented by the molecular IR spectrum.The samples used in this experiment as a model were prepared in pellet form, made from powdered pig's shin bone mixed with KBr (mass ratio of about 1:100).The spectra were obtained in transmission mode.Three different types of experiments were performed at each sample, which were subjected to: (a) fixed electric field (E < 40 kV/m), (b) variable electric field (0-40 kV/m), (c) compressive stress (P < 100 MPa).The obtained data have shown that the electric field and compressive stress on sample modified infrared spectra of the bone.Qualitative as well as quantitative changes in the spectral range between 900 cm -1 and 1200 cm -1 and the band at 562 cm -1 (PO 3- 4 asymmetric and symmetric stretching, respectively) were observed.The relative area obtained by decomposition of the PO 3- 4 band reaches an extreme value in the external compressive stress (10 MPa), that occur under physiological conditions.Based on presented data, it was proved that the applied factors (electric field, compressive stress) can change the oscillation energy and the number of molecule's degrees of freedom.