Formation of Organized Protein Thin Films with External Electric Field

Abstract

The effect of an external electric field on the formation of protein GlnB-Hs films and on its buffer solution on siliconized glass slides has been analyzed by current versus electric field curves and atomic force microscopy (AFM). The Herbaspirillum seropedicae GlnB protein (GlnB-Hs) is a globular, soluble homotrimer (36 kDa) with its 3-D structure previously determined. Concentrations of 10 nM native denatured GlnB-Hs protein were deposited on siliconized glass slides under ambient conditions. Immediately after solution deposition a maximum electric field of 30 kV/m was applied with rates of 3 V/s. The measured currents were surface currents and were analyzed as transport current. Electric current started to flow only after a minimum electric field (critical value) for the systems analyzed. The AFM images showed films with a high degree of directional organization only when the proteins were present in the solution. These results showed that the applied electric field favored directional organization of the protein GlnB-Hs films and may contribute to understand the formation of protein films under applied electric fields.

Bulky side chain effect of poly(N‐vinylcarbazole)‐based stacked polymer electrets on device performance parameters of transistor memories

“…Thus, the effect of SHE on the performances of devices might be achieved by conformational adjustment of polymers. Polymeric conformational transitions in thin film under electric field were widely observed . Furthermore, the view that neighboring carbazole groups of PVK formed π‐stacked structures under external electric field was also proposed .…”

Use of Protein Thin Film Organized by External Electric Field as a Template for Protein Crystallization

“…These images showed no evidence of orientation and a random distribution of buffer compounds (Figures 1c,f and 2c,f), similar to the pattern seen in the drop deposition protein films. Thus, the orientation would be related to the presence of large polar molecules, such as proteins, 25 but not to buffer components. Despite this, the buffer composition directly interferes in the distribution profile of structures on protein thin films, when exposed to electric field, as can be seen in Figures 1a,d and 2a,d. 2.2.…”

“…Each protein solution was dripped on siliconized cover slips (Hampton Research HR 3-231, 22 mm) inside channels (5 mm × 3 mm) made of silicon paste and conductive ink. 25 Each channel was filled with protein solution (20 μL), and then the EEF (300 V, 5 min) was applied using a conventional electrophoresis power supply. To determine the best conditions, the current was monitored as described in Ferreira et al (2015).…”

“…25 Each channel was filled with protein solution (20 μL), and then the EEF (300 V, 5 min) was applied using a conventional electrophoresis power supply. To determine the best conditions, the current was monitored as described in Ferreira et al (2015). The same protein solutions were used as control, by simple drop deposition on siliconized cover slips.…”

“…20 The use of an EEF during protein thin film formation was first described in a study with GlnB from Herbaspirillum seropedicae. 25 When the electric field was applied, the protein molecules were clearly oriented, as observed by atomic force microscopy (AFM) images. 25 Thus, it is expected that the films formed by the electric field have the potential to act as nucleation centers, which is the starting point for the development of the method proposed in this work.…”