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• 1. [Article] Electrical Detection of the Temperature Induced Melting Transition of a DNA Hairpin Covalently Attached to Gold Interdigitated Microelectrodes

  The temperature induced melting transition of a self-complementary DNA strand covalently attached at the 5' end to the surface of a gold interdigitated microelectrode (GIME) was monitored in a novel, label-free, ...

  Citation × Citation Citation Abstract Copy Title: Electrical Detection of the Temperature Induced Melting Transition of a DNA Hairpin Covalently Attached to Gold Interdigitated Microelectrodes Author: Brewood, Greg P., Rangineni, Yaswanth, Fish, Daniel J., Bhandiwad, Ashwini, Evans, David R., Solanki, Raj, Benight, Albert S. Year: 2008 The temperature induced melting transition of a self-complementary DNA strand covalently attached at the 5' end to the surface of a gold interdigitated microelectrode (GIME) was monitored in a novel, label-free, manner. The structural state of the hairpin was assessed by measuring four different electronic properties of the GIME (capacitance, impedance, dissipation factor and phase angle) as a function of temperature from 25 degrees C to 80 degrees C. Consistent changes in all four electronic properties of the GIME were observed over this temperature range, and attributed to the transition of the attached single-stranded DNA (ssDNA) from an intramolecular, folded hairpin structure to a melted ssDNA. The melting curve of the self-complementary single strand was also measured in solution using differential scanning calorimetry (DSC) and UV absorbance spectroscopy. Temperature dependent electronic measurements on the surface and absorbance versus temperature values measured in solution experiments were analyzed assuming a two-state process. The model analysis provided estimates of the thermodynamic transition parameters of the hairpin on the surface. Two-state analyses of optical melting data and DSC measurements provided evaluations of the thermodynamic transition parameters of the hairpin in solution. Comparison of surface and solution measurements provided quantitative evaluation of the effect of the surface on the thermodynamics of the melting transition of the DNA hairpin. Title: Electrical Detection of the Temperature Induced Melting Transition of a DNA Hairpin Covalently Attached to Gold Interdigitated Microelectrodes Author: Brewood, Greg P., Rangineni, Yaswanth, Fish, Daniel J., Bhandiwad, Ashwini, Evans, David R., Solanki, Raj, Benight, Albert S. Year: 2008 The temperature induced melting transition of a self-complementary DNA strand covalently attached at the 5' end to the surface of a gold interdigitated microelectrode (GIME) was monitored in a novel, label-free, manner. The structural state of the hairpin was assessed by measuring four different electronic properties of the GIME (capacitance, impedance, dissipation factor and phase angle) as a function of temperature from 25 degrees C to 80 degrees C. Consistent changes in all four electronic properties of the GIME were observed over this temperature range, and attributed to the transition of the attached single-stranded DNA (ssDNA) from an intramolecular, folded hairpin structure to a melted ssDNA. The melting curve of the self-complementary single strand was also measured in solution using differential scanning calorimetry (DSC) and UV absorbance spectroscopy. Temperature dependent electronic measurements on the surface and absorbance versus temperature values measured in solution experiments were analyzed assuming a two-state process. The model analysis provided estimates of the thermodynamic transition parameters of the hairpin on the surface. Two-state analyses of optical melting data and DSC measurements provided evaluations of the thermodynamic transition parameters of the hairpin in solution. Comparison of surface and solution measurements provided quantitative evaluation of the effect of the surface on the thermodynamics of the melting transition of the DNA hairpin. Close

• 2. [Article] Differential Effects of the Hydrophobic Surfactant Proteins on the Formation of Inverse Bicontinuous Cubic Phases

  Prior studies have shown that the biological mixture of the two hydrophobic surfactant proteins, SP-B and SP-C, produces faster adsorption of the surfactant lipids to an air/water interface, and that they ...

  Citation × Citation Citation Abstract Copy Title: Differential Effects of the Hydrophobic Surfactant Proteins on the Formation of Inverse Bicontinuous Cubic Phases Author: Chavarha, Mariya, Loney, Ryan W., Kumar, Kamlesh, Rananavare, Shankar B., Hall, Stephen B. Year: 2012 Prior studies have shown that the biological mixture of the two hydrophobic surfactant proteins, SP-B and SP-C, produces faster adsorption of the surfactant lipids to an air/water interface, and that they induce 1-palmitoyl-2-oleoyl phosphatidylethanolamine (POPE) to form inverse bicontinuous cubic phases. SP-B has a much greater effect than SP-C on adsorption. If the two proteins induce formation of the bicontinuous structures and faster adsorption by similar mechanisms, then they should also have differential ability to form the cubic phases. To test this hypothesis, we measured small angle X-ray scattering on the individual proteins combined with POPE. SP-B replicated the doserelated ability of the combined proteins to induce the cubic phases at temperatures more than 25°C below the point at which POPE alone forms the curved inverse-hexagonal phase. With SP-C, diffraction from cubic structures was either absent or present only with larger amounts of protein at low intensities. The correlation between the structural effects of inducing curved structures and the functional effects on the rate of adsorption fits with the model in which SP-B promotes adsorption by facilitating formation of a negatively curved, rate-limiting intermediate structure. Title: Differential Effects of the Hydrophobic Surfactant Proteins on the Formation of Inverse Bicontinuous Cubic Phases Author: Chavarha, Mariya, Loney, Ryan W., Kumar, Kamlesh, Rananavare, Shankar B., Hall, Stephen B. Year: 2012 Prior studies have shown that the biological mixture of the two hydrophobic surfactant proteins, SP-B and SP-C, produces faster adsorption of the surfactant lipids to an air/water interface, and that they induce 1-palmitoyl-2-oleoyl phosphatidylethanolamine (POPE) to form inverse bicontinuous cubic phases. SP-B has a much greater effect than SP-C on adsorption. If the two proteins induce formation of the bicontinuous structures and faster adsorption by similar mechanisms, then they should also have differential ability to form the cubic phases. To test this hypothesis, we measured small angle X-ray scattering on the individual proteins combined with POPE. SP-B replicated the doserelated ability of the combined proteins to induce the cubic phases at temperatures more than 25°C below the point at which POPE alone forms the curved inverse-hexagonal phase. With SP-C, diffraction from cubic structures was either absent or present only with larger amounts of protein at low intensities. The correlation between the structural effects of inducing curved structures and the functional effects on the rate of adsorption fits with the model in which SP-B promotes adsorption by facilitating formation of a negatively curved, rate-limiting intermediate structure. Close