Chaperones in the endoplasmic reticulum (ER) control the flux of Ca2+ ions into mitochondria, thereby increasing or decreasing the energetic output of the oxidative phosphorylation pathway. An example is the abundant ER lectin calnexin, which interacts with sarco/endoplasmic reticulum Ca2+ ATPase (SERCA). We found that calnexin stimulated the ATPase activity of SERCA by maintaining its redox state. This function enabled calnexin to control how much ER Ca2+ was available for mitochondria, a key determinant for mitochondrial bioenergetics. Calnexin-deficient cells compensated for the loss of this function by partially shifting energy generation to the glycolytic pathway. These cells also showed closer apposition between the ER and mitochondria. Calnexin therefore controls the cellular energy balance between oxidative phosphorylation and glycolysis.

No abstract

Luminescent silicon nanoparticles have been widely recognized as an alternative for metal-based quantum dots (QDs) for optoelectronics partly because of the high abundance and biocompatibility of silicon. To date, the broad photoluminescence line width (often >100 nm) of silicon QDs has been a hurdle to achieving competitive spectral purity and incorporating them into lightemitting devices. Herein we report fabrication and testing of straightforward configuration of Fabry−Peŕot resonators that incorporates a thin layer of SiQD− polymer hybrid/blend between two reflective silver mirrors; remarkably these devices exhibit up-to-14-fold narrowing of SiQD emission and achieve a spectral bandwidth as narrow as ca. 9 nm. Our polymer-based, SiQD-containing Fabry− Peŕot resonators also provide convenient spectral tunability, can be prepared using a variety of polymer hosts and substrates, and enable rigid as well as flexible devices.

To address the issue of poor selectivity in nanotechnologydriven, portable nitroaromatic sensors, we have coupled a ratiometric photoluminescent sensor based on silicon quantum dots and fluorescent proteins with a colorimetric, enzyme-based sensor. Together, the sensors allow differentiation of nitroaromatic compounds�specifically, distinguishing acetylcholinergic nerve agents from the explosive compounds explored herein. The combined system can detect 2,4,6-trinitrotoluene, 2,4dinitrotoluene, and 4-nitrophenol with micromolar detection limits and affords subsequent differentiation from the nitro-containing nerve agent paraoxon. A prototype portable sensing device housing both technologies is presented and tested for achieving visual differentiation of the nitroaromatic explosives versus nerve agents. This demonstrates the advantage of merging elements of materials chemistry and biochemistry to devise customized sensors that can accurately identify hazardous chemical species.

To address the issue of poor selectivity in nanotechnology-driven, portable nitroaromatics sensors, we have coupled a ratiometric photoluminescence sensor based on silicon quantum dots and fluorescent proteins with a colorimetric enzyme-based sensor. Together, the sensors allow differentiation of nitroaromatic compounds – specifically, distinguishing acetylcholinergic nerve agents from the explosive compounds explored herein. The combined system can detect 2,4,6-trinitrotoluene, 2,4-dinitrotoluene and 4-nitrophenol with micromolar detection limits and affords subsequent differentiation from the nitro-containing nerve agent paraoxon. This demonstrates the advantage of merging elements of materials chemistry and biochemistry to devise customized sensors which can accurately identify hazardous chemical species.