Electronic Structures of Cr(III) and V(II) Polypyridyl Systems: Undertones in an Isoelectronic Analogy.

A recently reported description of the photophysical properties of V polypyridyl systems has highlighted several distinctions between isoelectronic, d, Cr, and V tris-homoleptic polypyridyl complexes of 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen). Here, we combine theory and experimental data to elucidate the differences in electronic structures. We provide the first crystallographic structures of the V complexes [V(bpy)](BPh) () and [V(phen)](OTf) () and observe pronounced trigonal distortion relative to analogous Cr complexes.

Hybrid paper and 3D-printed microfluidic device for electrochemical detection of Ag nanoparticle labels.

In the present article we report a new hybrid microfluidic device (hyFlow) comprising a disposable paper electrode and a three-dimensional (3D) printed plastic chip for the electrochemical detection of a magnetic bead-silver nanoparticle (MB-AgNP) bioconjugate. This hybrid device evolved due to the difficulty of incorporating micron-scale MBs into paper-only fluidic devices. Specifically, paper fluidic devices can entrap MB-containing conjugates within their cellulose or nitrocellulose fiber matrix.

Read-by-eye quantification of aluminum (III) in distance-based microfluidic paper-based analytical devices.

Herein we report the first two distance-based microfluidic paper-based analytical devices (μPADs) using fluorescence to quantify aluminum. In addition to their read-by-eye quantification, the devices are simple to fabricate, require no sample pretreatment or preconcentration, and have a shelf life of >5 months. The first device is designed in a "chemometer" format where the length of a fluorescent band linearly responds to an Al(III) concentration.

Multilayered Microfluidic Paper-Based Devices: Characterization, Modeling, and Perspectives.

Microfluidic paper-based analytical devices (μPADs) are simple but powerful analytical tools that are gaining significant recent attention due to their many advantages over more traditional monitoring tools. These include being inexpensive, portable, pump-free, and having the ability to store reagents. One major limitation of these devices is slow flow rates, which are controlled by capillary action in the hydrophilic pores of cellulosic paper.

Development of Paper-Based Analytical Devices for Minimizing the Viscosity Effect in Human Saliva.

Saliva as a sample matrix is rapidly gaining interest for disease diagnosis and point-of-care assays because it is easy to collect (non-invasive) and contains many health-related biomarkers. However, saliva poses particular problems relative to more common urine and blood matrices, which includes low analyte concentrations, lack of understanding of biomolecule transportation and inherent viscosity variability in human samples. While several studies have sought to improve assay sensitivity, few have addressed sample viscosity specifically.

Design considerations for reducing sample loss in microfluidic paper-based analytical devices.

The field of microfluidic paper-based analytical devices (μPADs) is most notably characterized by portable and low-cost analysis; however, struggles to achieve the high sensitivity and low detection limits needs required for many environmental applications hinder widespread adoption of this technology. Loss of analyte to the device material represents an important problem impacting sensitivity. Critically, we found that at least 50% of a Ni(II) sample is lost when being transported down a 30 mm paper channel that is representative of structures commonly found in μPADs.

Rapid flow in multilayer microfluidic paper-based analytical devices.

Microfluidic paper-based analytical devices (μPADs) are a versatile and inexpensive point-of-care (POC) technology, but their widespread adoption has been limited by slow flow rates and the inability to carry out complex in field analytical measurements. In the present work, we investigate multilayer μPADs as a means to generate enhanced flow rates within self-pumping paper devices. Through optical and electrochemical measurements, the fluid dynamics are investigated and compared to established flow theories within μPADs.

A selective distance-based paper analytical device for copper(II) determination using a porphyrin derivative.

Meso-tetrakis(1,2-dimethylpyrazolium-4-yl)porphyrin sulfonate (TDMPzP), a water-soluble porphyrin derivative, was synthesized and used as a colorimetric reagent for Cu detection on a microfluidic paper-based analytical device (µPAD) using distance-based quantification. TDMPzP showed a high selectivity for Cu detection in aqueous solutions. When Cu was added to the TDMPzP under acidic conditions, a color change from green to a pink was observed by the naked eye.

Critical interval of somal calcium transient after neurite transection determines B 104 cell survival.

Nerve cells may survive or die after axonal or dendritic transection. After neurite transection near (<50 mum) the cell body of Fura-2-loaded B 104 neuroblastoma (rat brain-derived) cells, the somal calcium concentration (SCC) undergoes a three-phase transient change: a rapid (0-0.15-min post-transection [PT]) rise phase, followed by an early (0.

Plasmalemmal sealing of transected mammalian neurites is a gradual process mediated by Ca(2+)-regulated proteins.

Cultured mammalian PC12 or B104 cells do not instantaneously restore a plasmalemmal barrier (seal) after neurite transection, as measured using fluorescent dye probes of various sizes and saline solutions with different [Ca(2+)](o). Rather, transected cells gradually (from 15 to 60 min postseverance) exclude probes (dye molecules) of progressively smaller size. Furthermore, an inhibitor (calpeptin) of a Ca(2+)-activated cysteine protease (calpain) and antibodies or toxins to a Ca(2+)-regulated protein (synaptotagmin) and other membrane fusion proteins (syntaxin and synaptobrevin) inhibit plasmalemmal sealing.