1:30 PM - 3:30 PM
[18p-P5-17] Optical measurement of the adsorption process of ferritin molecules onto air-water interface and STEM observation of the adsorbed molecules
Keywords:Ferritin, Laser scattering, Self-assembly
Ferritin is spherical protein with outer diameter of 12 nm and has a cavity with Inner diameter 7 nm inside, where a metal nanoparticle is formed in-vivo and in-vitro. If two-dimensional molecular film of ferritin is made on Si substrate, it can be applied to nanoelectronics devices. So far, there have been many reports about formation of two-dimensional molecular film with an ordered structures like crystal. In particular, air-water interface is a good place where a large two-dimensional single crystal of molecules is formed, therefore, it is appropriate for studying the mechanism of the crystallization. The present study aims at measuring the surface tension and viscosity by laser scattering device which was designed and manufactured by us. Furthermore, we observed the adsorbed molecules by STEM. We expect comparing these data allows us understand the mechanism of the crystallization.
The ferritin used here is N1LF displaying a short peptide, DYFSSPYYEQLF, on the molecular surface, which has strong affinity for carbon nanohorn. N1-LF was prepared by culturing E. coli and dissolved in 50 mM PIPES-NaOH up to the concentration of 5 ug/mL. Prior to the light scattering measurement, the material was kept in a thermostat at 37 ℃ for 30 min, and the sample was quickly poured into the quartz cell for the measurement.
The results showed that, after the sample solution was poured into the cell, the surface tension has kept unchanged for about 20 minutes until it started descending. On the other hand, the viscosity began to increase soon, and after the maximum point, it gradually decreased almost down to the initial value. This implies that the ferritin molecules accumulated beneath the water surface without being denatured for a while and then slowly decreases the surface tension due to their denaturing. The molecules at the air-water interface was transferred to a TEM grid at a certain time, and then observed by STEM. Small amount of molecules were observed, which indicates that the viscosity is very sensitive to the number of molecules. The analysis of the result will be presented in the session.
The ferritin used here is N1LF displaying a short peptide, DYFSSPYYEQLF, on the molecular surface, which has strong affinity for carbon nanohorn. N1-LF was prepared by culturing E. coli and dissolved in 50 mM PIPES-NaOH up to the concentration of 5 ug/mL. Prior to the light scattering measurement, the material was kept in a thermostat at 37 ℃ for 30 min, and the sample was quickly poured into the quartz cell for the measurement.
The results showed that, after the sample solution was poured into the cell, the surface tension has kept unchanged for about 20 minutes until it started descending. On the other hand, the viscosity began to increase soon, and after the maximum point, it gradually decreased almost down to the initial value. This implies that the ferritin molecules accumulated beneath the water surface without being denatured for a while and then slowly decreases the surface tension due to their denaturing. The molecules at the air-water interface was transferred to a TEM grid at a certain time, and then observed by STEM. Small amount of molecules were observed, which indicates that the viscosity is very sensitive to the number of molecules. The analysis of the result will be presented in the session.