No abstract

No abstract

Proteins have been increasingly suggested as suitable candidates for the fabrication of biological computers and other biomolecular-based electronic devices mainly due to their interesting structure-related intrinsic electrical properties. These natural biopolymers are environmentally friendly substitutes for conventional inorganic materials and find numerous applications in bioelectronics. Effective manipulation of protein biomolecules allows for accurate fabrication of nanoscaled device dimensions for miniaturized electronics. The prerequisite, however, demands an interrogation of its various electronic properties prior to understanding the complex charge transfer mechanisms in protein molecules, the knowledge of which will be crucial toward development of such nanodevices. One significantly preferred method in recent times involves the utilization of solid-state sensors where interactions of proteins could be investigated upon contact with metals such as gold. Therefore, in this work, proteins (hemoglobin and collagen) were integrated within a two-electrode system, and the resulting electronic profiles were investigated. Interestingly, structure-related electronic profiles representing semiconductivelike behaviors were observed. These characteristic electronic profiles arise from the metal (Au)−semiconductor (protein) junction, clearly demonstrating the formation of a Schottky junction. Further interpretation of the electronic behavior of proteins was done by the calculation of selected solid-state parameters. For example, the turn-on voltage of hemoglobin was measured to occur at a lower turn-on voltage, indicating the possible influence of the hem group present as a cofactor in each subunit of this tetrameric protein.

Deoxyribonucleic acid (DNA), the blueprint of life, has attracted recent attention concerning its potential applications in electronics. In order to realize these applications, charge transfer through the molecule has been subjected to numerous experimental and theoretical studies in the last few decades. As a result of varying experimental conditions, different electrical behaviors have been observed. The sensitive structure of DNA is influenced by extreme environmental conditions as shown in common characterization techniques. Finding a simple yet quantitative accurate method is more efficient for understanding the electronic properties of DNA. In this work, we have employed DNA-specific Schottky junctions integrated within a printed circuit board (PCB) to investigate the properties of the four nitrogenous bases of guanine (G), thymine (T), cytosine (C) and adenine (A) in short polynucleotide form. Acquisition and analysis of the current-voltage (I-V) profiles allowed measurement of selected solid-state parameters corresponding to each of the DNA polynucleotide base. While observing characteristic I-V profiles and parameters, significantly closer and higher conductive profiles were demonstrated for the purines (A and G) as compared to the highly similar profiles of the pyrimidines (T and C) which is in agreement with previous observations. The observations obtained from this work may, therefore, provide a clear conceptualization of the role of each nitrogenous base in charge transfer process through the DNA molecule and allow better understanding of the fingerprinting electronic properties of each base.

No abstract