Silver or gold? A comparison of nanoparticle modified electrochemical genosensors based on cobalt porphyrin-DNA.

We applied a cobalt-porphyrin modified DNA as electrochemical marker, which was attached to nanoparticles, to detect specific DNA sequences. We compare the performance of gold and silver NPs in oligonucleotide sensors to determine if a change in metal will lead to either higher sensitivity or different selectivity, based on the redox behaviour of silver vs. gold.

Approaching single DNA molecule detection with an ultrasensitive electrochemical genosensor based on gold nanoparticles and cobalt-porphyrin DNA conjugates.

We describe an ultrasensitive electrochemical genosensor based on gold nanoparticles and cobalt-porphyrin functionalised ssDNA probes. The sensitivity at the attomolar concentration level arises from an increased density of redox labels on the electrode surface compared to sensors without NP modification. The electrode detects as few as 23 DNA molecules, approaching single molecule detection.

Ion Channels Made from a Single Membrane-Spanning DNA Duplex.

Because of their hollow interior, transmembrane channels are capable of opening up pathways for ions across lipid membranes of living cells. Here, we demonstrate ion conduction induced by a single DNA duplex that lacks a hollow central channel. Decorated with six porpyrin-tags, our duplex is designed to span lipid membranes.

Neutral bis-macrocyclic nickel(II) and copper(II) complexes as π-donor receptors.

A new type of hetero- and homo-polynuclear complexes of copper(II) and nickel(II) containing 1,2,3-triazole groups in polymethylene chains have been synthesized and characterized using NMR and electrochemical methods. The triazole link facilitates the synthesis of hetero-dinuclear macrocyclic complexes. Introducing the triazole unit into the complex structure can lead to increased stability of the bis-macrocyclic system and to obtain electroactive receptors for electron-deficient molecules.

Pseudorotaxane based on tetraazamacrocyclic copper complex and dibenzocrown ether.

Host-guest interactions between two electron-rich dibenzocrown ethers and electron deficient macrocyclic copper(II) tetraimine complexes lead to the formation of pseudorotaxane in solution. The interactions are enhanced with the copper(III) complex compared to that of the copper(II) form as shown by the electrochemical studies. The larger--30-membered dibenzocrown donor interacted with the copper complex stronger than the smaller ones as revealed by NMR and electrochemical methods.

Macrocyclic multicenter complexes of nickel and copper of increasing complexity.

Multicenter (bi-, tri-, and tetranuclear) tetraazamacrocyclic complexes were self-assembled from Ni and Cu tetraazamacrocyclic mononuclear units and α,ω-diamines as building blocks. The structures of all compounds studied were proved by spectroscopic methods (ESI MS and NMR spectroscopy). Electrochemical experiments revealed reversible one-electron electrode processes at each of the Ni(2+) and Cu(2+) centers with formation of metal cations in oxidation state +3.

Face-to-face dinuclear scaffolds composed of tetraazamacrocyclic charged and neutral complexes.

A new family of bismacrocyclic homo- and heteronuclear Ni and Cu complexes has been synthesized and characterized. The ligand scaffold is comprised of two 14-membered tetraazamacrocyclic sites held in cofacial orientation. The dinuclear complexes are unique in that one macrocyclic center is neutral while the other one is charged, although the ligand backbones are nearly identical.

Interactions of dithiolated tetraazamacrocyclic copper(II) and nickel(II) complexes self-assembled on gold electrodes with pi-electron deficient molecules in solution.

Self-assembled monolayers of dithiolated neutral monotetraazamacrocyclic complexes of copper(II) and nickel(II) can provide molecularly defined platforms for the formation of a pseudorotaxane-like nanostructures on the gold electrode surface. We propose these complexes as pi-donor building blocks for the construction of new molecular devices. We show that these perpendicularly oriented macrocyclic complexes anchored to the electrode surface act as pi-electron rich species interacting with pi-electron deficient compounds dissolved in solution, such as fluorine derivatives of tetracyanoquinodimethane (F(4)TCNQ) or a charged bismacrocyclic tetraaza complex of copper(II).