Mifflin Amanda L, Konek Christopher T, Geiger Franz M
Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
J Phys Chem B. 2006 Nov 16;110(45):22577-85. doi: 10.1021/jp063089p.
This work examines the binding behavior of the antibiotic oxytetracycline (OTC) to mineral oxide/water interfaces in the presence and absence of organic functional groups using the interface-specific technique second harmonic generation (SHG). Studies show that OTC binding to fused quartz, methyl ester, carboxylic acid, and alkyl interfaces is fully reversible and highly dependent on solution pH, with appreciable adsorption occurring only at pH 8. Relative surface coverage at pH 8 is highest for the polar organic-functionalized surfaces, and surface saturation occurs for the methyl ester-functionalized fused quartz/water interface at 2 x 10(-5) M. Adsorption isotherm measurements indicate that the binding process is controlled by hydrogen bonding and hydrophobic interactions, with free energies of adsorption on the order of -40 kJ/mol for all interfaces studied. The results indicate that OTC transport in the environment will depend heavily on soil pH and composition and have implications for the development of bacterial antibiotic resistance.
本研究利用界面特异性技术——二次谐波产生（SHG），考察了在有或无有机官能团存在的情况下，抗生素土霉素（OTC）与矿物氧化物/水界面的结合行为。研究表明，OTC与熔融石英、甲酯、羧酸和烷基界面的结合是完全可逆的，且高度依赖于溶液pH值，仅在pH 8时才会发生明显吸附。在pH 8时，极性有机官能化表面的相对表面覆盖率最高，甲酯官能化的熔融石英/水界面在2×10⁻⁵ M时发生表面饱和。吸附等温线测量表明，结合过程受氢键和疏水相互作用控制，所有研究界面的吸附自由能约为-40 kJ/mol。结果表明，OTC在环境中的迁移将严重依赖于土壤pH值和组成，并对细菌抗生素耐药性的发展具有影响。
