Abstract:Abstract:The electrochemical studies on the behaviors and recognition of DNA have attracted considerable attention. DNA biosensors based on nucleic acid hybridization process are rapidly being developed towards the goal of rapid and inexpensive diagnosis of genetic and infectious diseases. This brief review focuses on the current state of the DNA electrochemical sensors with emphasis on recent advances, challenges and trends. The works on DNA electrochemical behaviors, recognition and detection in our group in… Show more
“…The potential in which this peak appears is 0.35 V versus Ag/AgCl RE. These results confirm the combination of DNA electrochemical biosensors with PCR techniques provide a platform for the development of electrochemical sequence detection of low content of DNA (Marrazza et al, 2000;Ye and Ju, 2003).…”
Section: Measurement System Characterizationsupporting
“…The potential in which this peak appears is 0.35 V versus Ag/AgCl RE. These results confirm the combination of DNA electrochemical biosensors with PCR techniques provide a platform for the development of electrochemical sequence detection of low content of DNA (Marrazza et al, 2000;Ye and Ju, 2003).…”
Section: Measurement System Characterizationsupporting
“…We also note that control experiments performed by addition of FTMA to solutions of DNA pre-exposed to oxidizing potentials of 400 mV for 1−1.5 h were indistinguishable from experiments performed using DNA not exposed to oxidizing potentials (see Supporting Information). These results and others − suggest that the oxidizing potential used in the in situ transformation of the FTMA in preformed complexes does not damage the DNA (see below for additional comment). 6 Autocorrelation functions of 5 μM DNA and 30 μM FTMA (in 1 mM Li 2 SO 4 ) at a scattering angle of 90° and temperature of 25 °C.…”
We report characterization of aqueous solutions of dilute Lambda phage DNA containing the redox-active surfactant (11-ferrocenylundecyl)trimethylammonium bromide (FTMA) as a function of the oxidation state of the FTMA. FTMA undergoes a reversible one-electron oxidation from a reduced state that forms micelles in aqueous solution to an oxidized state (containing the ferrocenium cation) that does not self-associate in solution. This investigation sought to test the hypothesis that FTMA can be used to achieve reversible control over the conformation of DNA-surfactant complexes in solution. Whereas DNA adopts extended coil conformations in aqueous solutions, our measurements revealed that addition of reduced FTMA (2-5 microM) to aqueous solutions of DNA (5 microM in nucleotide units) resulted in coexistence of extended coils and compact globules in solution. At higher concentrations of reduced FTMA (up to 30 microM), the DNA was present as compact globules only. In contrast, oxidized FTMA had no measurable effect on the conformation of DNA, allowing DNA to maintain an extended coil state up to a concentration of 75 microM oxidized FTMA. We further demonstrate that it is possible to chemically or electrochemically transform the oxidation state of FTMA in preformed complexes of FTMA and DNA, thus achieving in situ control over the conformations of the DNA in solution. These results provide guidance for the design of surfactant systems that permit active control of DNA-surfactant interactions.
“…This could be important in electrochemical sensor and biosensor applications as well as the catalysis of biochemical reactions. For example, under certain conditions, covalent bonding can occur between the carboxyl group and deoxyguanosine (dG) residue of DNA [44] . Thus, DNA could be immobilized on a graphite surface with the assistance of EAK16-II assembled nanostructures.…”
Ionic-complementary peptides are novel nano-biomaterials with a variety of biomedical applications including potential biosurface engineering. This study presents evidence that a model ionic-complementary peptide EAK16-II is capable of assembling/coating on hydrophilic mica as well as hydrophobic highly ordered pyrolytic graphite (HOPG) surfaces with different nano-patterns. EAK16-II forms randomly oriented nanofibers or nanofiber networks on mica, while ordered nanofibers parallel or oriented 60° or 120° to each other on HOPG, reflecting the crystallographic symmetry of graphite (0001). The density of coated nanofibers on both surfaces can be controlled by adjusting the peptide concentration and the contact time of the peptide solution with the surface. The coated EAK16-II nanofibers alter the wettability of the two surfaces differently: the water contact angle of bare mica surface is measured to be <10°, while it increases to 20.3±2.9° upon 2 h modification of the surface using a 29 µM EAK16-II solution. In contrast, the water contact angle decreases significantly from 71.2±11.1° to 39.4±4.3° after the HOPG surface is coated with a 29 µM peptide solution for 2 h. The stability of the EAK16-II nanofibers on both surfaces is further evaluated by immersing the surface into acidic and basic solutions and analyzing the changes in the nanofiber surface coverage. The EAK16-II nanofibers on mica remain stable in acidic solution but not in alkaline solution, while they are stable on the HOPG surface regardless of the solution pH. This work demonstrates the possibility of using self-assembling peptides for surface modification applications.
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