ABSTRACT
This article aims at developing a new technology and instrument to explore the effect of gamma radiation on bone material. Exoelectron emission (EEE) phenomenon underlies a new electron spectroscopy to explore alteration of the electronic structurally dependence properties of bone material. The development of EEE technology for exploring the gamma radiation effects on bones is of high importance. Moreover, the influence of gamma radiation with different energies on the bone structure is discussed. It was found that the changes in EEE vary with radiation energy and radiation dose and that the response is non-linear.
ABSTRACT
Fourier transform infrared microscopy was used to investigate human cortical bone samples before and after treatment with increasing doses of X-ray radiation. Especially the spectral region of the v1 and v3 phosphate vibrations of hydroxyapatite, the main mineral component of bone, and the region of the amide I and amide II vibrational bands due to the collagen extracellular matrix were examined. Major spectral changes in the phosphate region between 1250-1000 cm(-1) occur after irradiation doses between 1 and 4 Gray. These findings are explained by a decrease in size of mineral crystallites and by variances of the toichiometric/non-stoichiometric apatite composition. The Ca2+ /PO4(3-) /HPO4(2-) composition in the biological apatite is altered near the bone surface. The secondary structure of the collagen matrix is not affected by cumulative irradiation up to doses of 15 Gray as indicated by the unchanged frequency maximum and contour shape of the amide I band between 1600-1700 cm(-1) . However, side chain carboxylate groups of the collagen matrix that are involved in coordination with apatite bound calcium ions are partially removed by decarboxylation upon irradiation. Concomitantly, a loss of acidic phosphate groups due to a formation of phosphate groups with bound calcium is observed. These changes on a molecular level can be correlated with alterations in the mechanical properties of the bone samples, e.g. with an increased embrittlement as deduced from experiments with a scanning acoustic microscope.
Subject(s)
Bone and Bones/radiation effects , Amides/chemistry , Amides/radiation effects , Bone and Bones/chemistry , Calcium/chemistry , Calcium/radiation effects , Carboxylic Acids/chemistry , Carboxylic Acids/radiation effects , Collagen/chemistry , Collagen/radiation effects , Crystallography , Durapatite/chemistry , Durapatite/radiation effects , Humans , Microspectrophotometry , Phosphates/chemistry , Phosphates/radiation effects , Radiation Dosage , Spectroscopy, Fourier Transform Infrared , X-RaysABSTRACT
Radiation applied for therapy and diagnostics damages molecular/atomic couples of biotissues, bones being among them. As a result, electron peculiarities and mechanical behavior of the latter are altered. Correlation between strength of the irradiated bone and its electron features explored due to photo- and exoelectron emission measurements is reviewed.
Subject(s)
Models, Biological , Tibia/radiation effects , Tibia/ultrastructure , Animals , Cattle , Compressive Strength , Elasticity , Radiation Dosage , Spectrometry, X-Ray Emission/methods , Spectrophotometry, Ultraviolet/methods , Tibia/chemistry , Tibia/physiopathology , Ultraviolet Rays , Weight-BearingABSTRACT
A surface of the bone is a site, where the highest mechanical tensions are developed. Therefore, this place has a special importance to provide the strength. The latter depends on a bone tissue atomic/molecular structure. The present report reviews recent results demonstrating how damaged atomic/molecular bonds situated in the surface layer (interface) of the bone have an influence on its strength. The bonds were excited owing to ultraviolet radiation (UR) supplied by a Mercury tube. As the result the strength was decreased. To explore the reason of this phenomenon the atomic force microscopy operated in a tapping mode (AFM) and photoelectron (PE)/exoelectron (EE) analysis was applied. AFM demonstrated a surface topography varied from a homogenize to an island-type under UR. Such a behavior was repeated periodically in monotonically increased radiation exposure. Selective etching of the bone evidenced that reconstruction of the interface layer coupling mineral and organic phases stipulated such a synergetic. EE demonstrated a concentration of destroyed bonds also had a similar regularity depended on exposure. PE measurements discovered responsible for this centres placed at 5.35 and 5.65 eV below a vacuum level.
Subject(s)
Bone and Bones/radiation effects , Animals , Biomechanical Phenomena , Bone and Bones/physiopathology , Cattle , In Vitro Techniques , Microscopy, Atomic Force , Spectrum Analysis , Ultraviolet RaysABSTRACT
Exoelectron spectroscopy and ultrasound velocity (USV) measurements have been applied to analyse both the electron and mechanical behaviour of compact bone tissue and its main components--collagen and hydroxyapatite (HAP)--in the temperature range 20-80 degrees C. The special exoelectron method with additional IR illumination has been pioneered for the above objective. Thermally induced variations of the electron structure of bone tissue and HAP were manifested at 55 degrees C, but in collagen they were near 75 degrees C. The greatest decrease in USV was at 35-65 degrees C in collagen and at 55-70 degrees C in bone. No changes of USV in HAP were revealed. The coincidence of temperatures of the exoemission maxima and of the USV most expressed gradient in fresh bone and collagen proves the correlation between electron and mechanical behaviour during heating, connected with the partial denaturation of collagen.
