Dna Electrophoresis at Surfaces

Abstract

Summary:During this year we performed two major projects:I. We developed a detailed theoretical model which complements our experiments on surface DNA electrophoresis. We found that it was possible to enhance the separation of DNA chains by imposing a chemical nanoscale pattern on the surface. This approach utilized the surface interaction effect of the DNA chains with the substrate and is a refinement to our previous method in which DNA chains were separated on homogeneous flat surfaces. By introducing the nano-patterns on the surface, the conformational changes of DNA chains of different lengths can be amplified, which results in the different friction strengths with the substrate surface. Our results also show that, when compared to the DNA electrophoresis performed on homogeneous flat surfaces, nanopatterned surfaces offer a larger window in choosing different surface interactions to achieve separation. (See manuscript below which is being submitted to the journal Electrophoresis for publication. )II. In collaboration with a large international manufacturer of skin care products we also embarked on a project involving photo toxicity of titanium dioxide nanoparticles, which are a key ingredient in sunscreen and cosmetic lotions. The results clearly implicated the nanoparticles in catalyzing damage to chromosomal DNA. We then used this knowledge to develop a polymer/anti-oxidant coating which prevented the photocatalytic reaction on DNA while still retaining the UV absorptive properties of the nanoparticles. The standard gel electrophoresis was not sufficient These results are being submitted for publication to JACS (see attached). Personnel:Two graduate students were supported by this grant; Binquan Li and Xiaohua Fang.Both have obtained their PhD this year and are employed as postdoctoral associated at Columbia University.One undergraduate student was supported; Eric Petersen who is now a sophomore at Harvard University.One Research Associate Young Soo Seo, was also supported. He is now employed by LG Electronics.One faculty member; Dilip Gersappe received summer (2 months) salary. Our results also show that, when compared to the DNA electrophoresis performed on homogeneous flat surfaces, nanopatterned surfaces offer a larger window in choosing different surface interactions to achieve separation.6