Electro-Infiltration of Cytochrome C into a Porous Silicon Network, and Its Effect on Nucleation and Protein Crystallization—Studies of the Electrical Properties of Porous Silicon Layer-Protein Systems for Applications in Electron-Transfer Biomolecular Devices

Laura Serrano-De La Rosa,Abel Moreno,Mauricio Pacio

doi:10.3390/cryst7070194

Laura Serrano-De La Rosa, Abel Moreno + Show 1 more

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https://doi.org/10.3390/cryst7070194

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Abstract

In this work, we report the electrical properties of cytochrome C (Cyt C) inside porous silicon (PSi). We first used two techniques of protein infiltration: classic sitting drop and electrochemical migration methods. The electrochemically assisted cell, used for the infiltration by electro-migration, improved the Cyt C nucleation and the crystallization behavior due to the PSi. We were able to carry out the crystallization thanks to the previous infiltration of proteins inside the Si pores network. We then continued the protein crystal growth through a vapor diffusion set-up. Secondly, we applied both forward and reverse bias currents only to the infiltrated Cyt C. Finally, the electrical characteristics were compared to the control (the protein molecules of which were not infiltrated) and to the samples without protein infiltration. The linker used in the sitting drop method influenced the electrical properties, which showed a modification in the current density. The simple drop method showed a current density of ~42 A/cm2; when employing the electrochemical cell technique, the current density was ~318 A/cm2; for the crystallized structures, it was ~0.908 A/cm2.

Highlights

Porous Si (PSi) is a versatile material that has generated interest because of its compatibility with biological materials and its different applications, such as in medicine [1,2] and molecular electronics [3,4,5]
The PSi was stabilized by thermal oxidation at 1073.15 K, generating Si–O bonds
The PSi layer was obtained by the electrochemical etching of p-type Si with 60% porosity determined by the gravimetric method

Summary

Introduction

Porous Si (PSi) is a versatile material that has generated interest because of its compatibility with biological materials and its different applications, such as in medicine [1,2] and molecular electronics [3,4,5]. Cytochrome C is a protein whose solid-state electrical properties have been studied in recent years [6,7,8]. The most common is the drop infiltration method or covalent bond immobilization [11,12], which consists of modifying the functional group of the PSi surface by thermal oxidation and subsequently with two silane groups. This method serves as a binder to immobilize the protein, thereby forming covalent bonds of the functional groups

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