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Stable
isotope
197
Au
Relative
atomic mass
Mole
fraction
196.966 569
1
Gold isotopes in biology
195
Au has been used to study particle movement within the lungs of rats (Figure 1) [534]. 198 Au
was used in a study to model gold cycling in plants. This study demonstrated that gold particles
are retained by humates (organic constituents of soil), which contain fulvic acid, humic acid,
ulmic acid, and lignin, and would therefore be likely to accumulate in mull humus or forest litter
[535].
Gold isotopes in medicine
198
Au has several medical uses. It can be used as both a diagnostic tool and a treatment option for
cancer [536, 537].
a. As a diagnostic tool, colloidal 198 Au is injected into the affected organ. Normal cells will
take up the gold colloid, but tumor cells will not. Therefore, an abscess will show up as a
“cold area” on a scan [536, 537].
b. As a treatment option, gold is intended to provide localized irradiation and can be
implanted or injected into the affected area. When implanted, the gold “seed” offers an
advantage over other materials in that it can be left in place due to its short half-life
(~65 h). As a colloidal injection, 198 Au has been found to produce improvement from a
wide variety of cancers [536, 537]. Figures 4.79.1 and 4.79.2 show squamous cell
carcinoma (cancer) on the lower left eyelid of a cat and the eyelid six weeks after
implantation of 198 Au seeds [538].
Recent studies have shown the effectiveness of 198 Au nanoparticles and nanodevices in reducing
tumor size in mice while minimizing radiation spread to other areas [536, 539, 540]. 198Au has
been studied and successfully used as an anti-inflammatory (property of a substance or treatment
that reduces the body tissues response to harmful stimuli such as swelling) for improving
arthritic conditions [541, 542].
Fig. 1: Squamous cell carcinoma on the lower left eyelid of a cat [538]. Need to obtain
permission from Copyright Clearance Center.
Fig. 2: The lower left eyelid six weeks after implantation of 198 Au seeds [538]. Need to obtain
permission Copyright Clearance Center.
Glossary
atomic number (Z) – The number of protons in the nucleus of an atom.
electron – elementary particle of matter with a negative electric charge and a rest mass of about
9.109 × 10–31 kg.
element (chemical element) – a species of atoms; all atoms with the same number of protons in
the atomic nucleus. A pure chemical substance composed of atoms with the same number of
protons in the atomic nucleus [703].
gamma rays (gamma radiation) – a stream of high-energy electromagnetic radiation given off
by an atomic nucleus undergoing radioactive decay. The energies of gamma rays are higher
than those of X-rays; thus, gamma rays have greater penetrating power.
half-life (radioactive) – the time interval that it takes for the total number of atoms of any
radioactive isotope to decay and leave only one-half of the original number of atoms. [return]
isotope – one of two or more species of atoms of a given element (having the same number of
protons in the nucleus) with different atomic masses (different number of neutrons in the
nucleus). The atom can either be a stable isotope or a radioactive isotope.
neutron – an elementary particle with no net charge and a rest mass of about 1.675 × 10–27 kg,
slightly more than that of the proton. All atoms contain neutrons in their nucleus except for
protium (1H).
proton – an elementary particle having a rest mass of about 1.673 × 10–27 kg, slightly less than
that of a neutron, and a positive electric charge equal and opposite to that of the electron. The
number of protons in the nucleus of an atom is the atomic number.
radioactive decay – the process by which unstable (or radioactive) isotopes lose energy by
emitting alpha particles (helium nuclei), beta particles (positive or negative electrons), gamma
radiation, neutrons or protons to reach a final stable energy state.
radioactive isotope (radioisotope) – an atom for which radioactive decay has been
experimentally measured (also see half-life).
stable isotope – an atom for which no radioactive decay has ever been experimentally measured.
X-rays – electromagnetic radiation with a wavelength ranging from 0.01 to 10 nanometers—
shorter than those of UV rays and typically longer than those of gamma rays.
References
534. G. Patrick, and Stirling, C. Environmental Health Perspectives. 97, 47 (1992).
535. K. C. Jones, and Peterson, P. J. Biogeochemistry. 7 (1), 3 (1989).
536. N. Chanda, Kan, P., Watkinson, L. D., Shukla, R., Zambre, A., Carmack, T. L.,
Engelbrecht, H., Lever, J. R., Katti, K., Fent, G. M., Casteel, S. W., Smith, C. J., Miller, W. H.,
Jurisson, S., Boote, E., Robertson, J. D., Cutler, C., Dobrovolskaia, M., Kannan, R., and Katti, K.
V. Nanomedicine, Nanotechnology, Biology and Medicine. 6 (2), 201 (2010).
537. C. W. H. Havard, and McAlister, J. The British Medical Journal. 2 (5551), 555 (1967).
538. a. R. S. C. Hardman. Australian Veterinary Journal. 79, 604 (2001).
539. M. K. Khan, Minc, L. D., Nigavekar, S. S., Kariapper, M. S. T., Nair, B. M., Schipper,
M., Cook, A. C., Lesniak, W. G., and Balogh, L. P. Nanomedicine. 4 (1), 57 (2008).
540. H. B. Wheeler, Jaques, W. E., and Botsford, T. W. Annals Of Surgery. 141 (2), 208
(1955).
541. A. M. Spencer, Patel, M.P., Smits, B.J., and Williams, J.D.F. The British Medical
Journal. 4 (5937), 153 (1974).
542. J. R. Topp, Cross, E. G., and Fam, A. G. CMA Journal. 112, 1085 (1975).
703. I. U. o. P. a. A. Chemistry. Compendium of Chemical Terminology, 2nd ed. (the "Gold
Book"). Blackwell Scientific Publications, Oxford (1997).