Preparation and characterization of zinc oxide nanoparticles and their sensor applications for electrochemical monitoring of nucleic acid hybridization

The interaction of PLGA-chitosan Nanoplexes with ocular mucosa was investigated ex vivo and in vivo to assess their potential as ocular delivery system. Fluorescent Rhodamine Nanoplexes (Rd-Nanoplexes) were prepared by ionotropic gelation method. The size and morphology of Nanoplexes was investigated by TEM, SEM and PCS. The corneal retention, uptake and penetration of Nanoplexes were analyzed by spectrofluorimetry and confocal microscopy. Corneas from Rd-Nanoplexes-treated rabbits were evaluated for the in vivo uptake and ocular tolerance. The Nanoplexes prepared were round with a mean diameter of 115.6±17nm and the encapsulation efficiency of Rd was 59.4±2.5%. Data from ex vivo and in vivo studies showed that the amounts of Rd in the cornea were significantly higher for Nanoplexes than for a control Rd solution, these amounts being fairly constant for up to 24h. Confocal microscopy of the corneas revealed paracellular and transcellular uptake of the Nanoplexes. The uptake mechanism postulated was adsorptive-mediated endocytosis and opening of the tight junctions between epithelial cells. No alteration was microscopically observed after ocular surface exposure to Nanoplexes. Taken together, these data demonstrate that Nanoplexes are potentially useful as ocular drug carriers.     

Chitosan/Ionic Liquid Composite Electrode for Electrochemical Monitoring of the Surface‐Confined Interaction Between Mitomycin C and DNA

In the present study a chitosan/ionic liquid modified pencil graphite electrode (CHIT‐IL‐PGEs) was developed for the first time for enhanced electrochemical monitoring of nucleic acid, and the interaction of the anticancer drug Mitomycin C (MC) and calf thymus double stranded DNA (dsDNA) by measuring the oxidation signals of MC and guanine in the same voltammetric scale. Differential pulse voltammetry, cyclic voltammetry and electrochemical impedance spectroscopy techniques were used to evaluate the performance of the CHIT‐IL based biosensor on electrochemical monitoring of DNA, and drug‐DNA interaction. The experimental parameters, IL, dsDNA and MC concentration and the interaction time were then optimized.     

Complexes of Iron(III) and Chrom(III) Salen and Saloph Schiff Bases with Bridging 2,4,6-tris(4-nitrophenylimino-4′-formylphenoxy)-1,3,5-triazine

Four new trinuclear Fe(III) and Cr(III) complexes involving tetradenta Schiff bases N,N′-bis(salicylidene)ethylenediamine-(salenH₂) or bis(salicylidene)-o-phenylenediamine-(saloph H₂) with 2,4,6-tris(4-nitrophenylimino-4′-formylphenoxy)-1,3,5-triazine (TNPI-TRIPOD) have been synthesized and characterized by means of elemental analysis carrying out ¹H-NMR., IR spectroscopy, thermal analyses and magnetic susceptibility measurements. The complexes can also be characterized as high-spin distorted octahedral Fe(III) and Cr(III) bridged by nitro. The nitro play a role as bridges for weak anti-ferromagnetic intramolecular exchange.     

Electrochemical Detection of Activated Protein C Using an Aptasensor Based on PAMAM Dendrimer Modified Pencil Graphite Electrodes

Electrochemical aptasensing of APC was carried out using PAMAM dendrimer modified pencil graphite electrodes (PGEs) for the first time herein. Poly(amidoamine) dendrimer having 16 succinamic acid surface groups (generation 2, G2‐PS) modified PGEs were developed, and then were utilized for APC monitoring using differential pulse voltammetry, electrochemical impedance spectroscopy and cyclic voltammetry. The selectivity of single‐use aptasensor was tested against to other proteins; BSA and THR as well as to the affinity of APC binding to different DNA aptamer, or oligonucleotide. Voltammetric APC detection was also explored in a diluted fetal bovine serum resulting with a detection limit DL as 1.5 µg/mL.     

Flavonol Glycosides and Iridoids from Asperula lilaciflora

A new flavonol glycoside, quercetin 3‐O‐[6′′′‐O‐3,5‐dihydroxycinnamoyl‐β‐glucopyranosyl‐(1→2)]‐β‐galactopyranoside (named lilacifloroside; 1 ) and a new iridoid 2 (named asperulogenin), were isolated from the aerial parts of Asperula lilaciflora in addition to eight known secondary metabolites, i.e., quercetin, kaempferol, quercetin 3‐O‐β‐glucopyranosyl‐(1→2)‐β‐galactopyranoside, quercetin 3‐O‐β‐glucopyranosyl‐(1→2)‐arabinopyranoside, asperuloside, deacetylasperulosidic acid, asperulosidic acid methyl ester, and chlorogenic acid. The structures were elucidated on the basis of extensive 1D‐ and 2D‐NMR experiments as well as MS data. Compound 1 contains the rare 3,5‐dihydroxycinnamoyl moiety in its structure. This work constitutes the first phytochemical study of the title plant.     

Magnetic bead-based label-free electrochemical detection of DNA hybridization.

Magnetic bead capture has been used for eliminating non-specific adsorption effects hampering label-free detection of DNA hybridization based on stripping potentiometric measurements of the target guanine at graphite electrodes. In particular, the efficient magnetic separation has been extremely useful for discriminating against unwanted constituents, including a large excess of co-existing mismatched and non-complementary oligomers, chromosomal DNA, RNA and proteins. The new protocol involves the attachment of biotinylated oligonucleotide probes onto streptavidin-coated magnetic beads, followed by the hybridization event, dissociation of the DNA hybrid from the beads, and potentiometric stripping measurements at a renewable graphite pencil electrode. Such coupling of magnetic hybridization surfaces with renewable graphite electrode transducers and label-free electrical detection results in a greatly simplified protocol and offers great promise for centralized and decentralized genetic testing. A new magnetic carbon-paste transducer, combining the solution-phase magnetic separation with an instantaneous magnetic collection of the bead-captured hybrid, is also described. The characterization, optimization and advantages of the genomagnetic label-free electrical protocol are illustrated below for assays of DNA sequences related to the breast-cancer BRCA1 gene.     

High scotopic/photopic ratio white-light-emitting diodes integrated with semiconductor nanophosphors of colloidal quantum dots

We propose and demonstrate single-chip white-light-emitting diodes (WLEDs) integrated with semiconductor nanophosphors of colloidal quantum dots for high scotopic/photopic (S/P) ratio. These color conversion WLEDs achieve S/P ratios over 3.00, which exceeds the current limit of 2.50 in common lighting technologies, while sustaining sufficient levels of color rendering index.