FT-NIR Spectroscopy of some long-chain fatty acids and alcohols

Fourier-transform (FT) near-infrared (NIR) spectroscopy has proved to be a powerful technique in investigating structure and thermodynamic properties of long-chain fatty acids and alcohols. In order to extract useful information from the NIR spectra, bands due to the second as well as first overtones of OH-stretching modes of the monomeric forms were employed. It has been also found that two-dimensional (2D) NIR correlation spectroscopy can accentuate useful information often obscured in the complicated NIR spectral data set.     

Highly sensitive detection of S-nitrosylated proteins by capillary gel electrophoresis with laser induced fluorescence

S-nitrosylated proteins are biomarkers of oxidative damage in aging and Alzheimer's disease (AD). Here, we report a new method for detecting and quantifying nitrosylated proteins by capillary gel electrophoresis with laser induced fluorescence detection (CGE-LIF). Dylight 488 maleimide was used to specifically label thiol group (SH) after switching the S-nitrosothiol (S-NO) to SH in cysteine using the "fluorescence switch" assay. In vitro nitrosylation model-BSA subjected to S-nitrosoglutathione (GSNO) optimized the labeling reactions and characterized the response of the LIF detector. The method proves to be highly sensitive, detecting 1.3 picomolar (pM) concentration of nitrosothiols in nanograms of proteins, which is the lowest limit of detection of nitrosothiols reported to date. We further demonstrated the direct application of this method in monitoring protein nitrosylation damage in MQ mediated human colon adenocarcinoma cells. The nitrosothiol amounts in MQ treated and untreated cells are 14.8±0.2 and 10.4±0.5 pmol/mg of proteins, respectively. We also depicted nitrosylated protein electrophoretic profiles of brain cerebrum of 5-month-old AD transgenic (Tg) mice model. In Tg mice brain, 15.5±0.4 pmol of nitrosothiols/mg of proteins was quantified while wild type contained 11.7±0.3 pmol/mg proteins. The methodology is validated to quantify low levels of S-nitrosylated protein in complex protein mixtures from both physiological and pathological conditions.     

An organic programmable diode with pentacene, zinc oxide nanoparticles and polymethylsilsesquioxane

In this paper, we proposed an organic programmable diode as a memory device. This device consists of layers of pentacene and zinc oxide nanoparticles embedded in polymethylsilsesquioxane. The device exhibits a change in current flow of an order up to 10⁵ and is comparable or better to many reported organic diode memory devices. A two-barrier model has been used to explain the memory effect of the organic diode. The device can be written and erased multiple times similar to a flash memory.     

<Emphasis Type="Italic">S</Emphasis>-glutathionyl quantification in the attomole range using glutaredoxin-3-catalyzed cysteine derivatization and capillary gel electrophoresis with laser-induced fluorescence detection

S-glutathionylation (Pr–SSG) is a specific post-translational modification of cysteine residues by the addition of glutathione. S-Glutathionylated proteins induced by oxidative or nitrosative stress play an essential role in understanding the pathogenesis of the aging and age-related disorder, such as Alzheimer’s disease (AD). The purpose of this research is to develop a novel and ultrasensitive method to accurately and rapidly quantify the Pr–SSG by using capillary gel electrophoresis with laser-induced fluorescence detection (CGE-LIF). The derivatization method is based on the specific reduction of protein-bound S-glutathionylation with glutaredoxin (Grx) and labeling with thiol-reactive fluorescent dye (Dylight 488 maleimide). The experiments were performed by coupling the derivatization method with CGE-LIF to study electrophoretic profiling in in vitro oxidative stress model–S-glutathionylated bovine serum albumin (BSA-SSG), oxidant-induced human colon adenocarcinoma (HT-29) cells, brain tissues, and whole blood samples from an AD transgenic (Tg) mouse model. The results showed almost an eightfold increase in S-glutathionyl abundance when subjecting HT-29 cells in an oxidant environment, resulting in Pr–SSG at 232 ± 10.64 (average ±SD; n = 3) nmol/mg. In the AD–Tg mouse model, an initial quantitative measurement demonstrated the extent of protein S-glutathionylation in three brain regions (hippocampus, cerebellum, and cerebrum), ranging from 1 to 10 nmol/mg. Additionally, we described our developed method to potentially serve as a highly desirable diagnostic tool for monitoring S-glutathionylated protein profile in minuscule amount of whole blood. The whole blood samples for S-glutathionyl expression of 5-month-old AD–Tg mice are quantified as 16.3 μmol/L (=7.2 nmol/mg protein). Altogether, this is a fast, easy, and accurate method, reaching the lowest limit of Pr–SSG detection at 1.8 attomole (amol) level, reported to date.     

Novel synthetic luteolin analogue-caused sensitization of tumor necrosis factor-alpha-induced apoptosis in human tumor cells

Studies on the sensitization, by novel alkynyl luteolin analogues, of TNF-alpha-induced apoptosis in HeLa and HepG2 cells revealed that LA-12 showed better sensitizing effects on TNF-alpha-induced cell death than luteolin, suggesting great potential for alkynyl luteolin analogues in cancer therapy.     

Negative differential resistance of a metal–insulator–metal device with gold nanoparticles embedded in polydimethylsiloxane

Metal–insulator–metal (MIM) devices play an important role in information storage cells. In this research, a MIM with an insulator made from polydimethylsiloxane blended with gold nanoparticles has been investigated. The current–voltage characteristic demonstrates a negative differential resistance (NDR) and memory effect. This article attempts to explain the NDR and memory effect, using the charge trapping and releasing mechanisms of the gold nanoparticles and also electron tunneling mechanisms.     

Visual SNP genotyping using asymmetric PCR and split DNA enzymes

Harnessing and applying genomic technologies in resource limited environments demand a next generation of platforms, which are convenient, quick and easy to apply. We describe here a visual colour change assay that can be applied to SNP genotyping, which unlike traditional methods, does not adopt complicated procedures or expensive instrumentation, desirable features in bringing genetic capabilities outside the laboratory. Our strategy involved a two-step method that first enriched target genomic regions using asymmetric PCR, followed by direct in situ application of split DNA probes. In the presence of target sequences that perfectly matched the complementary probes, the split probes reassembled active DNAzymes, which catalysed a colour change reaction. A single-base mismatch (indicative of a polymorphism) prevented this reassembly and colour change, providing the means for accurate SNP calling. This is the first report, to our knowledge, that demonstrates successful visual SNP genotyping of actual human DNA samples using DNAzymes.     

Enzyme‐Responsive Multifunctional Magnetic Nanoparticles for Tumor Intracellular Drug Delivery and Imaging

Enzyme‐responsive, hybrid, magnetic silica nanoparticles have been employed for multifunctional applications in selective drug delivery and intracellular tumor imaging. In this study, doxorubicin (Dox)‐conjugated, enzyme‐cleavable peptide precursors were covalently tethered onto the surface of uniform silica‐coated magnetic nanoparticles through click chemistry. This enzyme‐responsive nanoparticle conjugate demonstrated highly efficient Dox release upon specific enzyme interactions in vitro. It also exhibits multiple functions in selective tumor intracellular drug delivery and imaging in the tumor cells with high cathepsin B expression, whereas it exhibited lower cytotoxicity towards other cells without enzyme expression.