Development of a diagnostic tool for detection of cancer : effect of transition metal ions on urine.

• Main Author: Tan, Nicholas Teng Hui.
• Other Authors: School of Chemical and Biomedical Engineering
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Chemical engineering::Biotechnology
• Online Access: http://hdl.handle.net/10356/16552
• Institution: Nanyang Technological University

Three transition metal ions (Fe3+, Ni2+, Co2+) were used to react with five major components of urine (urea, creatinine, oxaiic acid, uric acid and citric acid), simulated urine (a combination of the five components) and protein solutions (BSA, tryptose, β2-microglobulin). Their reactions resulted in the formation of complexes with different composition of bonds which were detected using UV spectrophotometry. To investigate the effect of transition metal ion concentration on metal-protein interactions, the transition metal ions were prepared in varying concentrations of 20mM, 40mM, 60mM. The amide group in proteins offer two potential binding atoms, oxygen and nitrogen, for complexation of transition metal ions. It is also possible that bonding of transition metal ions to the proteins occurred via side chains of the amino acid residues that contain sulfur, oxygen and nitrogen, which can act as donor atoms. After thorough testing of the three concentrations, metal-protein interactions were observed to be optimized at 40mM. Among the transition metal ions tested, Fe3+ ions showed the strongest interactions with the individual components of urine. Iron is well known for being the most versatile transition metal in redox reactions, thus explaining its higher reactivity with the components of urine compared to the Ni2+ or Co2+ ions. From the results obtained, creatinine had the strongest interaction with Fe3+ ions, as compared to the other major components of urine. This was probably due to the strong ability of creatinine to form a complex with Fe3+ ions, possibly through the oxygen and/or the ring of nitrogen of creatinine. The UV profiles of the interactions between simulated urine (a mixture of individual components of urine) and the Fe3+ ions suggest that creatinine is the main components of urine that interacts with Fe3+ ions. Therefore, it is crucial to remove the interactions of creatinine with Fe3+ ions so that the metal-protein interactions would not be masked when Fe3+ ions are used to identify biomarkers in urine.