Charge-Reversal NaCl/G-Quartets for Aggregation-Induced Mitochondrial MicroRNA Imaging and Ion-Interference Therapy.

Mitochondrial therapy is a promising new strategy that offers the potential to achieve precise disease diagnosis or maximum therapeutic response. However, versatile mitochondrial theranostic platforms that integrate biomarker detection and therapy have rarely been exploited. Here, we report a charge-reversal nanomedicine activated by an acidic microenvironment for mitochondrial microRNA (mitomiR) detection and ion-interference therapy. The transporter liposome (DD-DC) was constructed from a pH-responsive polymer and a positively charged phospholipid, encapsulating NaCl nanoparticles with coloading of the aggregation-induced emission (AIE) fluorogens AIEgen-DNA/G-quadruplexes precursor and brequinar (NAB@DD-DC). The negatively charged nanomedicine ensured good blood stability and high tumor accumulation, while the charge-reversal to positive in response to the acidic pH in the tumor microenvironment (TME) and lysosomes enhanced the uptake by tumor cells and lysosome escape, achieving accumulation in mitochondria. The subsequently released Na+ in mitochondria not only contributed to the formation of mitomiR-494 induced G-quadruplexes for AIE imaging diagnosis but also led to an osmolarity surge that was enhanced by brequinar to achieve effective ion-interference therapy.

Separable Microneedle for Integrated Hyperglycemia Sensing and Photothermal Responsive Metformin Release.

Microdevices that offer hyperglycemia monitoring and controllable drug delivery are urgently needed for daily diabetes management. Herein, a theranostic separable double-layer microneedle (DLMN) patch consisting of a swellable GelMA supporting base layer for glycemia sensing and a phase-change material (PCM) arrowhead layer for hyperglycemia regulation has been fabricated. The Cu-TCPP(Fe)/glucose oxidase composite and 3,3',5,5'-tetramethylbenzidine coembedded in the supporting base layer permit a visible color shift at the base surface in the presence of glucose via a cascade reaction, allowing for the in situ detection of glucose in interstitial fluid. The PCM arrowhead layer is encapsulated with water monodispersity melanin nanoparticles from Sepia officinalis and metformin that is imparted with a near-infrared ray photothermal response feature, which is beneficial to the controllable release of metformin for suppression of hyperglycemia. By applying the DLMN patch to the streptozotocin-induced type 2 diabetic Sprague-Dawley rat model, the results demonstrated that it can effectively extract dermal interstitial fluid, read out glucose levels, and regulate hyperglycemia. This DLMN-integrated portable colorimetric sensor and self-regulated glucose level hold great promise for daily diabetes management.

Dipole-Dipole Tuned Electronic Reconfiguration of Defective Carbon Sites for Efficient Oxygen Reduction into H2 O2.

Metal-free carbon-based materials are one of the most promising electrocatalysts toward 2-electron oxygen reduction reaction (2e-ORR) for on-site production of hydrogen peroxide (H2 O2 ), which however suffer from uncontrollable carbonizations and inferior 2e-ORR selectivity. To this end, a polydopamine (PDA)-modified carbon catalyst with a dipole-dipole enhancement is developed via a calcination-free method. The H2 O2 yield rate outstandingly reaches 1.8 mol gcat -1 h-1 with high faradaic efficiency of above 95% under a wide potential range of 0.4-0.7 VRHE , overwhelming most of carbon electrocatalysts. Meanwhile, within a lab-made flow cell, the synthesized ORR electrode features an exceptional stability for over 250 h, achieved a pure H2 O2 production efficacy of 306 g kWh-1 . By virtue of its industrial-level capabilities, the established flow cell manages to perform a rapid pulp bleaching within 30 min. The superior performance and enhanced selectivity of 2e-ORR is experimentally revealed and attributed to the electronic reconfiguration on defective carbon sites induced by non-covalent dipole-dipole influence between PDA and carbon, thereby prohibiting the cleavage of O-O in OOH intermediates. This proposed strategy of dipole-dipole effects is universally applicable over 1D carbon nanotubes and 2D graphene, providing a practical route to design 2e-ORR catalysts.

RNA-Cleaving DNAzyme-Based Amplification Strategies for Biosensing and Therapy.

Since their first discovery in 1994, DNAzymes have been extensively applied in biosensing and therapy that act as recognition elements and signal generators with the outstanding properties of good stability, simple synthesis, and high sensitivity. One subset, RNA-cleaving DNAzymes, is widely employed for diverse applications, including as reporters capable of transmitting detectable signals. In this review, the recent advances of RNA-cleaving DNAzyme-based amplification strategies in scaled-up biosensing are focused, the application in diagnosis and disease treatment are also discussed. Two major types of RNA-cleaving DNAzyme-based amplification strategies are highlighted, namely direct response amplification strategies and combinational response amplification strategies. The direct response amplification strategies refer to those based on novel designed single-stranded DNAzyme, and the combinational response amplification strategies mainly include two-part assembled DNAzyme, cascade reactions, CHA/HCR/RCA, DNA walker, CRISPR-Cas12a and aptamer. Finally, the current status of DNAzymes, the challenges, and the prospects of DNAzyme-based biosensors are presented.

The Role of Graphene Oxide in the Exothermic Mechanism of Al/CuO Nanocomposites.

Metastable intermixed composites (MICs) have received increasing attention in the field of energy materials in recent years due to their high energy and good combustion performance. The exploration of ways of improving their potential release of heat is still underway. In this study, Al-CuO/graphene oxide (GO) nanocomposites were prepared using a combination of the self-assembly and in-suit synthesis methods. The formulation and experimental conditions were also optimized to maximize the exothermic heat. The DSC analysis shows that the addition of the GO made a significant contribution to the exothermic effect of the nanothermite. Compared with the Al-CuO nanothermite, the exothermic heat of the Al-CuO/GO nanocomposites increase by 306.9-1166.3 J/g and the peak temperatures dropped by 7.9-26.4 °C with different GO content. The reaction mechanism of the nanocomposite was investigated using a DSC and thermal reaction kinetics analysis. It was found that, compared with typical thermite reactions, the addition of the GO changed the reaction pathway of the nanothermite. The reaction products included CuAlO2. Moreover, the combustion properties of nanocomposite were investigated. This work reveals the unique mechanism of GO in thermite reactions, which may promote the application of carbon materials in nanothermite.

Metal-Organic Framework-Loaded Engineering DNAzyme for the Self-Powered Amplified Detection of MicroRNA.

DNAzyme shows great promise in designing a highly sensitive and specific sensing platform; however, the low cellular uptake efficiency, instability, and especially the insufficient cofactor supply inhibit the intracellular molecule sensor applications. Herein, we demonstrate a novel type of DNAzyme-based self-driven intracellular sensor for microRNA (miRNA) detection in living cells. The sensor consists of a metal-organic framework [zeolite imidazole framework (ZIF-8)] core loaded with a shell consisting of a rationally designed DNAzyme, where the substrate strand is modified with FAM and BHQ-1 nearby both the sides of the restriction site, respectively, while the enzyme strand consists of two separate strands with a complementary fragment to the substrate strand and the targeting miRNA, respectively. The ZIF-8 nanoparticles enable the efficient delivery of DNAzyme into the cell and protect the DNAzyme from degradation. The pH-responsive ZIF-8 degradation is accompanied with the release of the DNAzyme and Zn2+ cofactors, and the intracellular target miRNAs recognize and activate the DNAzyme driven by the Zn2+ cofactors to cleave the substrate strand, resulting in the release of the FAM-labeled shorter product strand and increased fluorescence for miRNA detection. The self-driven approach can be generally applied to various miRNAs' detection through DNAzyme engineering.

A new highly active La2O3-CuO-MgO catalyst for the synthesis of cumyl peroxide by catalytic oxidation.

In this study, different magnesium, copper, lanthanide single metal, and composite multimetal oxide catalysts were prepared via the coprecipitation route for the aerobic oxidation of cumene into cumene hydroperoxide. All catalysts were characterized using several analytical techniques, including XRD, SEM, EDS, FT-IR, BET, CO2-TPD, XPS, and TG-DTG. La2O3-CuO-MgO shows higher oxidation activity and yield than other catalysts. The results of XRD and SEM studies show that the copper and magnesium particles in the catalyst are smaller in size and have a distribution over a larger area due to the introduction of the lanthanum element. The CO2-TPD results confirmed that the catalyst has more alkali density and alkali strength, which can excite active sites and prevent the decomposition of cumene hydroperoxide. XPS results show that due to the promotional effect of La2O3, there are more lattice and active oxygen species in the catalyst, which can effectively utilize the lattice defects under the strong interaction between metal oxides for rapid adsorption and activation, thus improving the oxidation performance. Besides, La2O3-CuO-MgO exhibits good stability and crystalline structure due to its high oxygen mobility inhibiting coking during the cycle stability test. Finally, the possible reaction pathway and promotional mechanism on La2O3-CuO-MgO in cumene oxidation are proposed. We expect this study to shed more light on the nature of the surface-active site(s) of La2O3-CuO-MgO catalyst for cumene oxidation and the development of heterogeneous catalysts with high activity in a wide range of applications.

Beam waist shrinkage of high-power broad-area diode lasers by mode tailoring.

A new approach was proposed and its role in improvement of the beam quality of high-power broad-area diode lasers was demonstrated, in which a composite arrow array and trench microstructure was used to suppress the beam waist and tailor the high order lateral modes. The beam waist shows a special shrinkage with increasing injection current resulting from the combined effect of mode tailoring and the thermal lens effect. A 58% improvement in lateral beam parameter product was realized compared with conventional broad-area diode lasers.

A High-Performance Primary Nanosheet Heterojunction Cathode Composed of Na0.44 MnO2 Tunnels and Layered Na2 Mn3 O7 for Na-Ion Batteries.

Owing to its large capacity and high average potential, the structure and reversible O-redox compensation mechanism of Na2 Mn3 O7 have recently been analyzed. However, capacity fade and low coulombic efficiency over multiple cycles have also been found to be a problem, which result from oxygen evolution at high charge voltages. Herein, a Na0.44 MnO2 ⋅Na2 Mn3 O7 heterojunction of primary nanosheets was prepared by a sol-gel-assisted high-temperature sintering method. In the nanodomain regions, the close contact of Na0.44 MnO2 not only supplies multidimensional channels to improve the rate performance of the composite, but also plays the role of pillars for enhancing the cycling stability and coulombic efficiency; this is accomplished by suppressing oxygen evolution, which is confirmed by high-resolution (HR)TEM, cyclic voltammetry, and charge/discharge curves. As the cathode of a Na-ion battery, at 200 mA g-1 after 100 cycles, the Na0.44 MnO2 ⋅Na2 Mn3 O7 heterojunction retains an 88 % capacity and the coulombic efficiency approaches 100 % during the cycles. At 1000 mA g-1 , the Na0.44 MnO2 ⋅Na2 Mn3 O7 heterojunction has a discharge capacity of 72 mAh g-1 . In addition, the average potential is as high as 2.7 V in the range 1.5-4.6 V. The above good performances indicate that heterojunctions are an effective strategy for addressing oxygen evolution by disturbing the long-range order distribution of manganese vacancies in the Mn-O layer.

Exploring the Performance Improvement of the Oxygen Evolution Reaction in a Stable Bimetal-Organic Framework System.

Despite wide applications of bimetallic electrocatalysis in oxygen evolution reaction (OER) owing to their superior performance, the origin of the improved performance remains elusive. The underlying mechanism was explored by designing and synthesizing a series of stable metal-organic frameworks (MOFs: NNU-21-24) based on trinuclear metal carboxylate clusters and tridentate carboxylate ligands. Among the examined stable MOFs, NNU-23 exhibits the best OER performance; particularly, compared with monometallic MOFs, all the bimetallic MOFs display improved OER activity. DFT calculations and experimental results demonstrate that introduction of the second metal atom can improve the activity of the original atom. The proposed model of bimetallic electrocatalysts affecting their OER performance can facilitate design of efficient bimetallic catalysts for energy storage and conversion, and investigation of the related catalytic mechanisms.