title: Pathological biominerals: Raman and infrared studies of bioapatite deposits in human heart valves.
abstract: We studied pathological bioapatite from patients undergoing valvular replacement due to severe aortic and mitral stenosis. Three different types of mineralized human cardiac valves were analyzed. We used infrared and Raman spectroscopy to infer the presence of the carbonate group and  evaluate the carbonate substitution in bioapatite structure. The Raman spectra showed that the pathological bioapatite is a B-type "carbonate-apatite" (CO(3)(2-) for PO(4)(3-)) similar to the major mineralized products derived from  normal biomineralization processes occurring in the human body. Fourier transform infrared spectra (FT-IR) confirmed the B-type carbonate substitution (CO(3)(2-) for PO(4)(3-)) and showed evidence for the partial replacement of [OH] by [CO(3)]  (A-type substitution). The carbonate content of the samples inferred by the spectroscopic measurements is in good agreement with the range of values estimated for biological apatite. On the contrary, the crystal size of the pathological apatite estimated using the percentage area of the component  at 1059 cm(-1) of the infrared spectrum is in the nanometer range and it is significantly smaller than the crystal size of normal mineralized tissues.
authors.affiliation: Dept. of Physics, Sapienza University of Rome, Italy 00185.
authors.forename: Sara
authors.initials: S
authors.lastname: Mangialardo
authors.forename: Valentina
authors.initials: V
authors.lastname: Cottignoli
authors.forename: Elena
authors.initials: E
authors.lastname: Cavarretta
authors.forename: Loris
authors.initials: L
authors.lastname: Salvador
authors.forename: Paolo
authors.initials: P
authors.lastname: Postorino
authors.forename: Adriana
authors.initials: A
authors.lastname: Maras
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001031:Apatites / Q000737:chemistry* / Q000378:metabolism; D002114:Calcinosis / Q000378:metabolism / Q000473:pathology*; D003094:Collagen / Q000737:chemistry / Q000378:metabolism; D005260:Female; D006351:Heart Valves / Q000737:chemistry* / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013055:Spectrophotometry, Infrared / Q000379:methods*; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D001031:Apatites; C030782:carboapatite; D003094:Collagen