Interdigitated Electrode Biosensor Based on Plasma-Deposited TiO2 Nanoparticles for Detecting DNA.

Bioelectrodes mediated by metal oxide nanoparticles have facilitated the development of new sensors in medical diagnosis. High-purity TiO2 nanoparticles (NPs) were synthesized through thermal plasma and deposited directly on an interdigitated electrode. The surface of the TiO2-deposited electrode was activated with (3-aminopropyl) triethoxysilane (APTES) followed by fixing the single-stranded probe deoxyribonucleic acid (DNA) to fabricate the DNA biosensor. The structural properties of the deposited TiO2 nanoparticles were analyzed using a transmission electron microscope (TEM), X-ray diffraction (XRD), and a dynamic light scattering (DLS) system. The chemical composition and structural properties of the TiO2 nanoparticle layer and the fixed layer were analyzed by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). E. coli O157:H7, a well-known pernicious pathogenic bacterial species, was detected as a target DNA of the prepared DNA biosensor, and the characteristics of DNA detection were determined by the current change using a picoammeter. The degree of binding between the probe DNA and the target DNA was converted into an electrical signal using the picoammeter method to quantitatively analyze the concentration of the target DNA. With the specificity experiment, it was confirmed that the biosensor was able to discriminate between nucleotides with mismatched, non-complementary, or complementary sequences.

Facilitated Ion Transport in Smectic Ordered Ionic Liquid Crystals.

A novel ionic mixture of an imidazolium-based room-temperature ionic liquid containing ethylene-oxide-functionalized phosphite anions is fabricated, which, when doped with lithium salt, self-assembles into a smectic-ordered ionic liquid crystal through Coulombic interactions between the ion species. Interestingly, the smectic order in the ionic-liquid-crystal ionogel facilitates ionic transport.