Adsorption to Solid Interfaces 
Aquatic Environments: 
Organic Pollutants,Biomolecules, 
and Antibiotic Resistant Genes



Friday, December 2, 2005, 3:30 PM

Room 833 SWM Building

Dr. Helen Nguyen - Yale University


The first part of this presentation describes the development of a method for accurately estimating the equilibrium partitioning of non-ionic organic compounds (NOCs) between water and the natural organic matter in soils and sediments based on polyparameter linear free energy relationships (pp-LFER). This thermodynamic-based approach is capable of describing relevant intermolecular interactions (e.g. van-der-Waals and electron-donor/acceptor) between sorbed molecules and partitioning media. This method was shown to outperform traditional approaches for predicting the absorptive interactions of polar NOCs. The second part of this presentation focuses on the adhesion of antibiotic resistant plasmid DNA to mineral surfaces. This study uses a quartz crystal microbalance with dissipation (QCM-D) to measure adhesion rates and to determine the structure of the adhered layer of supercoiled plasmid DNA onto a silica surface. The data from simultaneous monitoring of variations in frequency and dissipation energy suggest that the adhered DNA layer is less fluidic in the presence of divalent cations compared to monovalent cations. The QCM-D technique is complemented by the dynamic light scattering technique to determine the diffusion coefficients of DNA molecules as a function of solution ionic compositions.