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Understanding the electronic properties of single- and double-stranded DNA

Daraghma SMA, Talebi S, Periasamy V

Eur Phys J E Soft Matter, 2020 Jun 19;43(6):40.
PMID: 32557121 DOI: 10.1140/epje/i2020-11965-8

Understanding the charge transfer mechanism through deoxyribonucleic acid (DNA) molecules remains a challenge for numerous theoretical and experimental studies in order to be utilized in nanoelectronic devices. Various methods have attempted to investigate the conductivity of double-stranded (ds-) and single-stranded DNA (ssDNA) molecules. However, different electronic behaviors of these molecules are not clearly understood due to the complexity and lack of accuracy of the methods applied in these studies. In this work however, we demonstrated an electronic method to study the electrical behavior of synthetic ssDNA or dsDNA integrated within printed circuit board (PCB)-based metal (gold)-semiconductor (DNA) Schottky junctions. The results obtained in this work are in agreement with other studies reporting dsDNA as having higher conductivity than ssDNA as observed by us in the range of 4-6μA for the former and 2-3μA for the latter at an applied bias of 3V. Selected solid-state parameters such as turn-on voltage, series resistance, shunt resistance, ideality factor, and saturation current were also calculated for the specifically designed ss- and dsDNA sequences using the thermionic emission model. The results also showed that the highest conductance was observed for dsDNA with guanine and cytosine base pairs, while the lowest conductance was for ssDNA with adenine and thymine bases. We believe the results of this preliminary work involving the gold-DNA Schottky junction may allow the interrogation of DNA charge transfer mechanisms and contribute to better understanding its elusive electronic properties.
Spinopelvic imbalances are associated with worse postoperative functional outcomes in patients undergoing total hip arthroplasty

Zandi R, Manafi-Rasi A, Talebi S, Ehsani A, Salarzadeh-Jenatabadi H

Eur J Orthop Surg Traumatol, 2023 Dec;33(8):3603-3609.
PMID: 37248436 DOI: 10.1007/s00590-023-03600-3

PURPOSE: We aimed to investigate the relationship between spinopelvic imbalances and functional disabilities after total hip arthroplasty in an at least two years of follow-up.
METHODS: Patients with normal sagittal alignment and normal motion (PI-LL 10°) were defined as control, and patients with any of sagittal alignment or motion abnormalities were defined as case groups. Visual Analog Scale, SF-36, Harris hip score, HOOS-JR, and complications were recorded.
RESULTS: The differences of the means of Harris hip score, HOOS-JR, SF-36, and VAS score in the control and case groups were statistically significant. The mean of these parameters in patients with sagittal balanced (PI-LL 10°). Same results were noted in patients with decreased (∆SS 10°).
CONCLUSION: Our observations indicate that spinopelvic imbalances are associated with worse postoperative functional outcomes in patients undergoing total hip arthroplasty.
Sorption of Pb(ll) by poly(hydroxamic acid) grafted oil palm empty fruit bunch

Haron MJ, Tiansin M, Ibrahim NA, Kassim A, Wan Yunus WM, Talebi SM

Water Sci Technol, 2011;63(8):1788-93.
PMID: 21866782

This paper describes the sorption of Pb(ll) from aqueous solution. Oil palm empty fruit bunch (OPEFB) fiber was first grafted with poly(methylacrylate) and then treated with hydroxylammonium chloride in alkaline medium to produce hydroxamic acid (PHA) grafted OPEFB. Sorption of Pb(ll) by PHA-OPEFB was maximum at pH 5. The sorption followed the Langmuir model with maximum capacityof 125.0 mg g-1 at 25 degrees C. The sorption process was exothermic, as shown by the negative value of enthalpy change, Delta H0. The free energy change (DeltaG0) for the sorption was negative, showing that the sorption process was spontaneous. A kinetic study showed that the Pb(ll) sorption followed a second order kinetic model.
Fulltext Novel same-metal three electrode system for cyclic voltammetry studies

Periasamy V, Elumalai PNN, Talebi S, Subramaniam RT, Kasi R, Iwamoto M, et al.

RSC Adv, 2023 Feb 14;13(9):5744-5752.
PMID: 36816072 DOI: 10.1039/d3ra00457k

Conventional three-electrode systems used in electrochemical measurement demand time-consuming and maintenance intensive procedures to enable accurate and repeatable electrochemical measurements. Traditionally, different metal configurations are used to establish the electrochemical gradient required to acquire the redox activity, and vary between different electrochemical measurement platforms. However, in this work, we report using the same metal (gold) for the counter, working and reference electrodes fabricated on a miniaturized printed circuit board (PCB) for a much simpler design. Potassium ferricyanide, widely used as a redox probe for electrochemical characterization, was utilized to acquire cyclic voltametric profiles using both the printed circuit board-based gold-gold-gold three-electrode and conventional three-electrode systems (glassy carbon electrode or graphite foil as the working electrode, platinum wire as the counter electrode, and Ag/AgCl as the reference electrode). The results show that both types of electrode systems generated similar cyclic voltammograms within the same potential window (-0.5 to +0.7 V). However, the novel PCB-based same-metal three-electrode electrochemical cell only required a few activation cycles and exhibited impressive cyclic voltametric repeatability with higher redox sensitivity and detection window, while using only trace amounts of solutions/analytes.
Fulltext Printed-Circuit-Board-Based Two-Electrode System for Electronic Characterization of Proteins

Talebi S, Daraghma SMA, Subramaniam RT, Bhassu S, Gnana Kumar G, Periasamy V

ACS Omega, 2020 Apr 14;5(14):7802-7808.
PMID: 32309689 DOI: 10.1021/acsomega.9b03831

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 semiconductive-like 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.