A new ternary Cu (II) complex with 4,7-dimethyl-1,10-phenanthroline and NOO-type tridentate Schiff base ligand: Synthesis,crystal structure,biomacromolecular interactions,and radical scavenging activities

NOO-type tridentate Schiff base, N-salicylidene-2-aminobenzoic acid, (H₂L), and its ternary Cu (II) complex containing H₂L Schiff base and 4,7-dimethyl-1,10-phenanthroline (4,7-dmphen), [Cu(4,7-dmphen)(H₂L)]₂7H₂O, have been synthesized and characterized by CHN analysis, ESI-MS, FTIR, and single-crystal X-ray diffraction techniques. The interaction of alone H₂L Schiff base ligand and ternary Cu (II) complex with biomacramolecules {calf thymus DNA (CT-DNA) and bovine serum albumin (BSA)} has been investigated by electronic absorption and fluorescence spectroscopy. The experimental results indicate that H₂L Schiff base ligand and ternary Cu (II) complex bind to CT-DNA by means of a moderate intercalation mode. Furthermore, the fluorescence quenching mechanism between H₂L Schiff base ligand and ternary Cu (II) complex with BSA possesses a static quenching process. Radical scavenging activity of H₂L Schiff base ligand and ternary Cu (II) complex was measured in terms of EC₅₀, using the DPPH and H₂O₂ methods. Biomacromolecule interactions and scavenging activity studies revealed that ternary Cu (II) complex yielded better results than H₂L Schiff base ligand alone.     

An ultrasensitive nucleic acid biosensor based on the catalytic oxidation of guanine by a novel redox threading intercalator

An ultrasensitive nucleic acid biosensor for the direct detection of attomoles nucleic acid in 1.0-5.0 [corrected] microl droplets is described which can be used for detection of cancer marker genes in mRNA extracted from human breast tissues without a RT-PCR step.     

Poly(3,4-ethylenedioxythiophene) (PEDOT) nanobiointerfaces: thin, ultrasmooth, and functionalized PEDOT films with in vitro and in vivo biocompatibility

Nanobiointerfaces were prepared based on an electrically conductive polyethylenedioxythiophene (PEDOT). Thin (<100 nm), ultrasmooth (roughness ( R(rms)) < 5 nm), and functionalized PEDOT films have been successfully electropolymerized using aqueous microemulsion. The microemulsion polymerization is found to be catalyzed in the presence of a low concentration of acid and allows for film formation from various functionalized ethylenedioxythiophenes (EDOTs) (e.g., EDOT-OH, C(2)-EDOT-COOH, C(4)-EDOT-COOH, C(2)-EDOT-NHS, EDOT-N(3)) and their mixtures. The nanobiointerfaces are compositionally tunable and controlled to deposit on selected electrode surfaces. They prefer orthogonal growth on patterned surfaces and are synthesized within seconds. These thin PEDOT films exhibit very low intrinsic cytotoxicity and display no inflammatory response upon implantation, making them ideal for biosensing and bioengineering applications.     

A DNA biosensor based on the electrocatalytic oxidation of amine by a threading intercalator

An electrochemical biosensor for the detection of DNA based a peptide nucleic acid (PNA) capture probe (CP) modified indium tin oxide electrode (ITO) is described in this report. After hybridization, a threading intercalator, N,N′-bis[(3-propyl)-imidazole]-1,4,5,8-naphthalene diimide (PIND) imidazole complexed with Ru(bpy)₂Cl (PIND-Ru, bpy = 2,2′-bipyridine), was introduced to the biosensor. PIND-Ru selectively intercalated to double-stranded DNA (ds-DNA) and became immobilized on the biosensor surface. Voltammetric tests showed highly stable and reversible electrochemical oxidation/reduction processes and the peak currents can directly be utilized for DNA quantification. When the tests were conducted in an amine-containing medium, Tris-HCl buffer for example, a remarkable improvement in the voltammetric response and noticeable enhancements of voltammetric and amperometric sensitivities were observed due to the electrocatalytic activity of the [Ru(bpy)₂Cl] redox moieties. Electrocatalytic current was observed when as little as 3.0 attomoles of DNA was present in the sample solution.     

Endomorphin analogues with balanced affinity for bothμ- andδ-opioid receptors

Analogues of endomorphin and tripeptidcs modified at positions 4 and 3,respectively,with various phenylalanine analogues were synthesized and their affinities for opioid receptors were evaluated.Most of the peptides exhibited potentμ-receptor affinity and selectivity,among them,compound 7(Dmt-Pro-Tmp-Tmp-NH_2) exhibited potent affinity for bothμ-andδ-receptors (K_iμ= 0.47 nmol/L,K_iδ= 1.63 nmol/L).     

On-site chemical reaction lights up protein assemblies in cells

Here we report a fast and effective method to visualize interactive proteins across intact mammalian cells via on-site formation of fluorescence using instant reaction of non-fluorescent fluorescamine with primary amines on proteins. Without interference by fluorescence background, this fluorogenic labelling opens a way for selective identification of primary amine-rich interacting proteins, efficient mapping and real-time monitoring of their spatial distribution in assemblies/network, and fast differentiation of cellular types. Without adverse effect on biological functions, this labelling method also provides new insights to comprehend important aspects of cellular functions of organelles and their relation to health imperfections for disease diagnostics and imaging-guided therapy.