Recognizing the translocation signals of individual peptide-oligonucleotide conjugates using an α-hemolysin nanopore

Two peptide-oligonucleotide conjugates are studied using an α-hemolysin nanopore to investigate their structural properties at the single-molecule level.     

Magnetic, electrochemical and spectroscopic properties of iron(III) amine-bis(phenolate) halide complexes

Eight new iron(III) amine-bis(phenolate) complexes are reported. The reaction of anhydrous FeX(3) salts (where X = Cl or Br) with the diprotonated tripodal tetradentate ligands 2-tetrahydrofurfurylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol), H(2)L1, 2-tetrahydrofurfurylamino-N,N-bis(2-methylene-4-methyl-6-tert-butylphenol), H(2)L2, and 2-methoxyethylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol), H(2)L3, 2-methoxyethylamino-N,N-bis(2-methylene-4-methyl-6-tert-butylphenol), H(2)L4 produces the trigonal bipyramidal iron(III) complexes, L1FeCl (1a), L1FeBr (1b), L2FeCl (2a), L2FeBr (2b), L3FeCl (3a), L3FeBr (3b), L4FeCl (4a), and L4FeBr (4b). All complexes have been characterized using electronic absorption spectroscopy, cyclic voltammetry and room temperature magnetic measurements. Variable temperature magnetic data were acquired for complexes 2b, 3a and 4b. Variable temperature M?ssbauer spectra were obtained for 2b, 3a and 4b. Single crystal X-ray molecular structures have been determined for proligand H(2)L4 and complexes 1b, 2b, and 4b.     

Bisglycine-substituted ferrocene conjugates

The solid state structures of three bissubstituted glycine ferrocene conjugates are described allowing a direct comparison of the structural parameters. Whereas the fully protected glycine ester Fc(Gly-OEt)₂ adopts a 1,3′-conformation leading exclusively to intermolecular H-bond formation, the free acid Fc(Gly-OH)₂ adopts the more compact 1,3′-comformation with intramolecular H-bonding. The same intramolecular H-bonding pattern is adopted by the glycine ferrocenophane Fc(Gly-CSA)₂.     

Ferrocene-peptido conjugates: from synthesis to sensory applications

The field of chemical and biological sensing is increasingly dependent on the availability of new functional materials that enhance the ability of the system to respond to chemical interactions. Organometallic bioconjugates derived from amino acids, peptides, proteins, peptide nucleic acids, and dendrimers have had a profound effect in this area and have endowed modern sensory systems with a superior performance. Owing to their fairly high stability, solubility in various solvents, and excellent redox properties, ferrocene and ferrocenyl conjugates have emerged as one of the most important classes of materials that enable direct observation of molecular interactions and as electron mediators. The low potential, reversible redox behavior of the ferrocene/ferrocenium couple is a unique property that finds widespread application in the design of sensory platforms. Currently, there is significant drive to exploit new organometallic systems, in which the presence of ferrocene acting as a redox center is critical and allows the design of highly sensitive electrochemical sensors for the sensing and recognition of a vast array of analytes.     

Studies of the interaction of two organophosphonates with nanostructured silver surfaces

Electrochemical cycling of silver surfaces in the presence of the organophosphonates paraoxon and malathion leads to changes in the electrochemical response of silver and the formation of silver nanostructures. Adsorption of the organophosphonates onto the silver surfaces causes a significant reduction in the observed current response due to an increase in the charge transfer resistance. Surface enhanced Raman spectroscopy (SERS) measurements indicate that paraoxon adsorbs with no structural changes, while malathion decomposes and a thiophosphonate interacts with the surface. The SERS study of these adsorbates was carried out by changing the electrochemical conditions and the concentration of the organophosphonates. The size of the nanostructures greatly influences the SERS signal and it is observed that the strongest enhancement is observed for mid-sized nanostructures with a uniform thickness on the surface. The limit of detection was shown to be in the range of 10 nM to 10 pM for paraoxon and malathion, respectively.