Hierarchical porous carbons derived from leftover rice for high performance supercapacitors

Abstract(#br)Biomass-derived porous carbons have been extensively investigated as potential electrode materials of electrochemical energy storage devices. Herein, hierarchical porous carbons with high specific surface area and large mesoporosity are successfully prepared from leftover rice, a common meal surplus, benefiting from its unique swelled structure and the activation effect of potassium hydroxide. The hierarchical porous carbons exhibit outstanding electrochemical energy storage performances in 1 M TEABF 4 /PC (propylene carbonate) electrolyte, including a high specific capacitance of 153.2 F g −1 at 0.2 A g −1 based on the active material, a high specific energy density of 22.6 Wh kg −1 at a power density of 21,503 W kg −1 based on the cells and over 87% capacitance retentions after 10,000 cycles at 1 A g −1 . Such excellent electrochemical performances demonstrate that leftover rice can be potentially applied as bioresource for high property porous carbon electrode materials of supercapacitors

Activity modulation and allosteric control of a scaffolded DNAzyme using a dynamic DNA nanostructure.

Recognition of the fundamental importance of allosteric regulation in biology dates back to not long after its discovery in the 1960s. Our ability to rationally engineer this potentially useful property into normally non-allosteric catalysts, however, remains limited. In response we report a DNA nanotechnology-enabled approach for introducing allostery into catalytic nucleic acids. Specifically, we have grafted one or two copies of a peroxidase-like DNAzyme, hemin-bound G-quadruplex (hemin-G), onto a DNA tetrahedral nanostructure in such a manner as to cause them to interact, modulating their catalytic activity. We achieve allosteric regulation of these catalysts by incorporating dynamically responsive oligonucleotides that respond to specific "effector" molecules (complementary oligonucleotides or small molecules), altering the spacing between the catalytic sites and thus regulating their activity. This designable approach thus enables subtle allosteric modulation in DNAzymes that is potentially of use for nanomedicine and nanomachines

A Sandwich-Structured Hybrid Anode With Nitrogen-Doped Amorphous Carbon Nanoarrays Vertically Anchoring on Graphene Nanoplatelets for High Rate Li Storage

Graphene is not an ideal anode material of Li-ion batteries because of its low packing density and low initial Coulombic Efficiency although it shows much higher specific capacity than graphite. Herein, we report a sandwich-structured hybrid anode material which integrates the nitrogen-doped amorphous carbon nanoarrays on both sides of graphene nanoplatelets. The former provides high capacity and excellent rate capability, while the latter stabilizes the cycle performance, both of them brought out outstanding electrochemical properties to the hybrid anode. High discharge capacities of 562 and 217 mA h g−1 are obtained at current densities of 0.1 and 3 A g−1, respectively, which are much higher than those of the starting graphene nanoplatelets (404 and 81 mA h g−1, respectively). Moreover, a discharge capacity of 540 mA h g−1 is maintained after 300 cycles at 0.5 A g−1, demonstrating an excellent cycle stability. This study provides a facile process to prop up the 2 D graphene nanoplatelets with vertically aligned carbon nanoarrays, which may push forward the application of graphene as anode material of Li-ion batteries because of the avoided aggregation and additional Li storage capacity contributed by the N-doped amorphous carbon

Constructing multidimensional conducting networks on LiCoO 2 cathode for enhanced rate performance and cycle stability

Abstract(#br)The effects of different assemblies of Super P, carbon nanotubes (CNTs) and graphene as hybrid conductive additives on the rate performance and cyclic stability of LiCoO 2 (LCO) cathode material were systematically investigated. The results indicated that adding graphene, CNTs or mixture of them into the conventional Super P conductive agent was effective to reduce the overall mass ratio of the carbonaceous conductive additive in the LCO electrode while significantly improving the rate performance and cycle stability. The best electrochemical performance was achieved on the electrode with 1 wt% (G + SP) and 1 wt% CNTs. Microstructural investigations indicated that a multidimensional conducting network had been constructed within this cathode, which provided efficient electronic and ionic transportation pathways, as evidenced by the reduced transport resistance and improved Li-ion diffusion dynamics. With this composition, a high discharge capacity of 118 mA h g −1 was obtained at a current density of 10 C (1400 mA g −1 ), and a high capacity retention of 92.3% was maintained after 100 cycles at 1 C

Real-time visualization of clustering and intracellular transport of gold nanoparticles by correlative imaging.

Mechanistic understanding of the endocytosis and intracellular trafficking of nanoparticles is essential for designing smart theranostic carriers. Physico-chemical properties, including size, clustering and surface chemistry of nanoparticles regulate their cellular uptake and transport. Significantly, even single nanoparticles could cluster intracellularly, yet their clustering state and subsequent trafficking are not well understood. Here, we used DNA-decorated gold (fPlas-gold) nanoparticles as a dually emissive fluorescent and plasmonic probe to examine their clustering states and intracellular transport. Evidence from correlative fluorescence and plasmonic imaging shows that endocytosis of fPlas-gold follows multiple pathways. In the early stages of endocytosis, fPlas-gold nanoparticles appear mostly as single particles and they cluster during the vesicular transport and maturation. The speed of encapsulated fPlas-gold transport was critically dependent on the size of clusters but not on the types of organelle such as endosomes and lysosomes. Our results provide key strategies for engineering theranostic nanocarriers for efficient health management

A dumbbell probe-mediated rolling circle amplification strategy for highly sensitive microRNA detection

We herein report the design of a dumbbell-shaped DNA probe that integrates target-binding, amplification and signaling within one multifunctional design. The dumbbell probe can initiate rolling circle amplification (D-RCA) in the presence of specific microRNA (miRNA) targets. This D-RCA-based miRNA strategy allows quantification of miRNA with very low quantity of RNA samples. The femtomolar sensitivity of D-RCA compares favorably with other existing technologies. More significantly, the dynamic range of D-RCA is extremely large, covering eight orders of magnitude. We also demonstrate miRNA quantification with this highly sensitive and inexpensive D-RCA strategy in clinical samples

High-Precision, In Vitro Validation of the Sequestration Mechanism for Generating Ultrasensitive Dose-Response Curves in Regulatory Networks

Our ability to recreate complex biochemical mechanisms in designed, artificial systems provides a stringent test of our understanding of these mechanisms and opens the door to their exploitation in artificial biotechnologies. Motivated by this philosophy, here we have recapitulated in vitro the “target sequestration” mechanism used by nature to improve the sensitivity (the steepness of the input/output curve) of many regulatory cascades. Specifically, we have employed molecular beacons, a commonly employed optical DNA sensor, to recreate the sequestration mechanism and performed an exhaustive, quantitative study of its key determinants (e.g., the relative concentrations and affinities of probe and depletant). We show that, using sequestration, we can narrow the pseudo-linear range of a traditional molecular beacon from 81-fold (i.e., the transition from 10% to 90% target occupancy spans an 81-fold change in target concentration) to just 1.5-fold. This narrowing of the dynamic range improves the sensitivity of molecular beacons to that equivalent of an oligomeric, allosteric receptor with a Hill coefficient greater than 9. Following this we have adapted the sequestration mechanism to steepen the binding-site occupancy curve of a common transcription factor by an order of magnitude over the sensitivity observed in the absence of sequestration. Given the success with which the sequestration mechanism has been employed by nature, we believe that this strategy could dramatically improve the performance of synthetic biological systems and artificial biosensors

Ubiquitination and degradation of SUMO1 by small-molecule degraders extends survival of mice with patient-derived tumors

Discovery of small-molecule degraders that activate ubiquitin ligase–mediated ubiquitination and degradation of targeted oncoproteins in cancer cells has been an elusive therapeutic strategy. Here, we report a cancer cell–based drug screen of the NCI drug-like compounds library that enabled identification of small-molecule degraders of the small ubiquitin-related modifier 1 (SUMO1). Structure-activity relationship studies of analogs of the hit compound CPD1 led to identification of a lead compound HB007 with improved properties and anticancer potency in vitro and in vivo. A genome-scale CRISPR-Cas9 knockout screen identified the substrate receptor F-box protein 42 (FBXO42) of cullin 1 (CUL1) E3 ubiquitin ligase as required for HB007 activity. Using HB007 pull-down proteomics assays, we pinpointed HB007’s binding protein as the cytoplasmic activation/proliferation-associated protein 1 (CAPRIN1). Biolayer interferometry and compound competitive immunoblot assays confirmed the selectivity of HB007’s binding to CAPRIN1. When bound to CAPRIN1, HB007 induced the interaction of CAPRIN1 with FBXO42. FBXO42 then recruited SUMO1 to the CAPRIN1-CUL1-FBXO42 ubiquitin ligase complex, where SUMO1 was ubiquitinated in several of human cancer cells. HB007 selectively degraded SUMO1 in patient tumor–derived xenografts implanted into mice. Systemic administration of HB007 inhibited the progression of patient-derived brain, breast, colon, and lung cancers in mice and increased survival of the animals. This cancer cell–based screening approach enabled discovery of a small-molecule degrader of SUMO1 and may be useful for identifying other small-molecule degraders of oncoproteins