The Role of Sirtuin-1 Isoforms in Regulating Mitochondrial Function.

The sirtuin-1 (SIRT1) gene contains multiple exons that usually undergo alternative splicing. The exclusion of one or more exons causes domain loss in the alternatively spliced isoforms and may change their functions. However, it is not completely established to what extent the loss of a non-catalytic domain could affect its regulatory function.

Impressively Printing Patterns of Gold and Silver Nanoparticles.

The optical and chemical properties of gold and silver nanoparticles make them useful for many applications, including surface enhanced spectroscopy-based biosensors, photostable colorants, enhanced photovoltaics, and nanoscale optical elements. We report a simple technique to generate patterns of gold and silver nanoparticles with controlled shape and shape-dependent optical properties using metal stamps to impress them onto a glass substrate or flexible polymers. The pressure flattens the nanoparticles, converting initially spherical nanoparticles into discs with reduced height and increased diameter.

Polyphenol effects on CuO-nanoparticle-mediated DNA damage, reactive oxygen species generation, and fibroblast cell death.

The ability of ten polyphenolic antioxidants to prevent CuO nanoparticle (CuO) and HO-mediated DNA damage and cytotoxicity was investigated. Five of the polyphenols (MEPCA, PREGA, MEGA, ECG, and EGCG) prevent CuO/HO-mediated DNA damage (IC values of 7.5-800 μM), three have no effect (PCA, VA, and EC), and two (GA and EGC) result in increased DNA damage.

Alternative Splicing Increases Sirtuin Gene Family Diversity and Modulates Their Subcellular Localization and Function.

Alternative splicing generates multiple distinct isoforms that increase transcriptome and proteome diversity. There are seven sirtuin genes in humans, each consists of multiple exons that are likely to undergo alternative splicing. Our aim was to characterize the effect of alternative splicing on the sirtuin genes.

Reactive oxygen species generation by copper(II) oxide nanoparticles determined by DNA damage assays and EPR spectroscopy.

Copper(II) oxide nanoparticles (CuO) have many industrial applications, but are highly cytotoxic because they generate reactive oxygen species (ROS). It is unknown whether the damaging ROS are generated primarily from copper leached from the nanoparticles, or whether the nanoparticle surface plays a significant role. To address this question, we separated nanoparticles from the supernatant containing dissolved copper, and measured their ability to damage plasmid DNA with addition of hydrogen peroxide, ascorbate, or both.

Tuning Localized Surface Plasmon Resonance Wavelengths of Silver Nanoparticles by Mechanical Deformation.

We describe a simple technique to alter the shape of silver nanoparticles (AgNPs) by rolling a glass tube over them to mechanically compress them. The resulting shape change in turn induces a red-shift in the localized surface plasmon resonance (LSPR) scattering spectrum and exposes new surface area. The flattened particles were characterized by optical and electron microscopy, single nanoparticle scattering spectroscopy, and surface enhanced Raman spectroscopy (SERS).

Removal of molecular adsorbates on gold nanoparticles using sodium borohydride in water.

The mechanism of sodium borohydride removal of organothiols from gold nanoparticles (AuNPs) was studied using an experimental investigation and computational modeling. Organothiols and other AuNP surface adsorbates such as thiophene, adenine, rhodamine, small anions (Br(-) and I(-)), and a polymer (PVP, poly(N-vinylpyrrolidone)) can all be rapidly and completely removed from the AuNP surfaces. A computational study showed that hydride derived from sodium borohydride has a higher binding affinity to AuNPs than organothiols.

Inner filter effect on surface enhanced Raman spectroscopic measurement.

Presented herein is a combined experimental and computational study of the gold nanoparticle (AuNP) inner filter effect on surface enhanced Raman spectroscopic (SERS) measurements. Using a bianalyte strategy in which dithiopurine (DTP) and ethanol were employed as the model analytes, we demonstrated that AuNPs enhance DTP's Raman signal but attenuate ethanol's Raman intensity. Combined time-resolved UV-vis and Raman measurements showed that AuNP aggregation has significant and an exactly opposite impact on the AuNP inner filter effect and SERS enhancement.