Cantilever-enhanced photoacoustic spectroscopy in the research of natural and synthetic calcium phosphate

Introduction. The photoacoustic spectroscopy (PAS) has many applications in different fields of research and industry. PA spectroscopy is a form of spectroscopy, which uses both - light and sound and is based on the absorption... [ view full abstract ]

Introduction. The photoacoustic spectroscopy (PAS) has many applications in different fields of research and industry. PA spectroscopy is a form of spectroscopy, which uses both - light and sound and is based on the absorption of electromagnetic radiation by analyte molecules. In 1997, Rehman and Bonfield were the first to study the structure of carbonated apatite with the FTIR-PAS with the MTech PAS cell. They concluded that PAS provides a sensitive, nondestructive and fast means of analyzing synthesized hydroxyapatite and carbonated apatites.
The aim of this study is to find advantages of PA spectroscopy with cantilever detector for the investigation of synthetic nanosized calcium apatite (in powder and on the pellet surface) and in archaeological human bone.
Materials and Methods. In this study, we evaluated:
-) synthesized nanosized calcium phosphate powders with variable A and B carbonate content and different degree of crystallinity;
-) the surface of uniaxially pressed calcium phosphate pellets before and after contact with bacteria;
-) archaeological human bones.
PA spectra were collected using an FTIR PA cell (Gasera PA301) at 450—4000 cm-1, at a resolution of 4 cm-1, with an average of 20 scans.
Results and Discussions. Spectra obtained by PA spectroscopy all show bands characteristic of carbonated calcium phosphates: v2CO3 in region 800—920 cm-1, v3CO3 in region 1400—1600 cm-1. Two processes were simultaneously followed on the pellet surface: identification of calcium phosphate bands and identification of bacteria from amide peaks. Human bones showed overlapping amide and carbonate bands in the region (900—1900 cm-1).
Conclusions. PA spectroscopy can be further used for sensitive, non-destructive analysis of synthesized nanosized carbonated calcium phosphate in the form of powder and on the surface and for archaeological bone.