Soft X-ray emission studies of biomaterials

Soft X-ray fluorescence measurements are used to characterize three groups of biomaterials: Vitamin B-12 and derivatives, antioxidants (aspirin and paracetamol), and human teeth. We show that the chemical bonding in Vitamin B-12 is characterized by the strong Co-C bond and the relatively weak Co-N bond. The Co-C bond in cyanocobalamin is found to be stronger than that of methylcobalamin leading to their different biological activity. The chemical bonding of paracetamol and aspirin is characterized by the formation of oxygen lone-pair pi-orbitals, which can neutralize free radicals and therefore be related to antioxidant activity of these compounds. Carbon Kalpha emission spectra of a caries lesion suggest that the CaCO3 like phase exists in sound enamel and that a selective loss of carbonate occurs during the early stages of a caries attack. (C) 2004 Elsevier B.V. All rights reserved.