3‐D Printing and Development of Fluoropolymer Based Reactive Inks

Engineering reactive materials is an ever present goal in the energetics community. The desire is to have energetics configured in such a manner that performance is tailored and energy delivery can be targeted. Additive manufacturing (3‐D printing) is one area that could significantly improve our capabilities in this area, if adequate formulations are developed. In this paper, fluoropolymer based reactive inks are developed with micron (mAl) and nanoscale aluminum (nAl) serving, as the fuel at high solids loading (up to 67 wt%) and their viscosity required for 3‐D printing is detailed. For the pen‐type technique and valves used in this work, it is required to have viscosities on the order of 10⁴–10⁵ cP. For printed traces with apparent diameters under <500 μm, the combustion velocities for both micron and nano scale aluminum formulations, are approximately identical: 30 ± 3 versus 32 ± 2 mm s^?1, respectively. Further increasing the apparent diameter is shown to increase the combustion velocity in the case of the nanoscale aluminum formulation by four‐fold over that of the micron scale aluminum formulation, but it plateaus as it approaches an apparent diameter of 2 mm. The results suggest with proper architecture that tailorable combustion rates and energy delivery are feasible.

     

Bending impact on the performance of a flexible Li4Ti5O12-based all-solid-state thin-film battery

The growing demand of flexible electronic devices is increasing the requirements of their power sources. The effect of bending in thin-film batteries is still not well understood. Here, we successfully developed a high active area flexible all-solid-state battery as a model system that consists of thin-film layers of Li₄Ti₅O₁₂, LiPON, and Lithium deposited on a novel flexible ceramic substrate. A systematic study on the bending state and performance of the battery is presented. The battery withstands bending radii of at least 14 mm achieving 70% of the theoretical capacity. Here, we reveal that convex bending has a positive effect on battery capacity showing an average increase of 5.5%, whereas concave bending decreases the capacity by 4% in contrast with recent studies. We show that the change in capacity upon bending may well be associated to the Li-ion diffusion kinetic change through the electrode when different external forces are applied. Finally, an encapsulation scheme is presented allowing sufficient bending of the device and operation for at least 500 cycles in air. The results are meant to improve the understanding of the phenomena present in thin-film batteries while undergoing bending rather than showing improvements in battery performance and lifetime.     

Impact of arteriovenous fistula cannulation on the quality of dialysis

Introduction: Adequate hemodialysis directly improves health. Puncturing an arteriovenous fistula (AVF) and the amount of blood recirculation greatly affect the quality of dialysis. Few studies have assessed the method to cannulate a fistula and its influence on efficiency of hemodialysis. Methods: This prospective pilot study included 14 patients with end‐stage renal failure receiving regular intermittent hemodialysis. Patients received three consecutive treatments with both needles directed upstream then three consecutive treatments with the venous needle directed upstream and the arterial needle directed downstream. With both techniques, the distance between the needles was kept constant at 2.5 cm. Recirculation rate and Kt/V ratio were measured during each treatment using thermodilution and a diascan Fresenius generator. Findings: The 14 patients received 84 hemodialysis sessions: i.e., 8 (57.1%) males and 6 (42.8%) females, mean age 62.3 ± 15.57 years. Results showed that mean recirculation rates and Kt/V did not significantly differ between the two techniques. Discussion: Because no significant difference was found between the two techniques, the direction of insertion of needles should be decided upon on a case‐by‐case basis depending on the anatomy of the AVF and the feasibility of the puncture.     

Autonomous Magnetic Microrobots by Navigating Gates for Multiple Biomolecules Delivery

The precise delivery of biofunctionalized matters is of great interest from the fundamental and applied viewpoints. In spite of significant progress achieved during the last decade, a parallel and automated isolation and manipulation of rare analyte, and their simultaneous on‐chip separation and trapping, still remain challenging. Here, a universal micromagnet junction for self‐navigating gates of microrobotic particles to deliver the biomolecules to specific sites using a remote magnetic field is described. In the proposed concept, the nonmagnetic gap between the lithographically defined donor and acceptor micromagnets creates a crucial energy barrier to restrict particle gating. It is shown that by carefully designing the geometry of the junctions, it becomes possible to deliver multiple protein‐functionalized carriers in high resolution, as well as MCF‐7 and THP‐1 cells from the mixture, with high fidelity and trap them in individual apartments. Integration of such junctions with magnetophoretic circuitry elements could lead to novel platforms without retrieving for the synchronous digital manipulation of particles/biomolecules in microfluidic multiplex arrays for next‐generation biochips.     

Research Advances in Microfiber Humidity Sensors

An overview of the numerous latest research in microfiber humidity sensors is carried out with a specific focus on measurement methods, humidity sensitive materials, probe structures, and sensing properties of different sensors. First, five mainstream measurement structures, including taper, fiber grating, coupler, resonator, and interferometer are reviewed. It is concluded that these measurement structures sense the physicochemical property variations of microfibers or sensitive films and exhibit the change of optical signal when exposed to environment. Second, the basic preparation methods, humidity‐sensing properties, and their advantages and disadvantages as humidity sensitive material are addressed. Then, the advantages and disadvantages of all the above sensing structures are also discussed and compared. Finally, the main existing problems and potential solutions of microfiber humidity sensors are pointed out.     

Template‐Free Fabrication of Mesoporous Alumina Nanospheres Using Post‐Synthesis Water‐Ethanol Treatment of Monodispersed Aluminium Glycerate Nanospheres for Molybdenum Adsorption

This work reports the template‐free fabrication of mesoporous Al₂O₃ nanospheres with greatly enhanced textural characteristics through a newly developed post‐synthesis “water‐ethanol” treatment of aluminium glycerate nanospheres followed by high temperature calcination. The proposed “water‐ethanol” treatment is highly advantageous as the resulting mesoporous Al₂O₃ nanospheres exhibit 2–4 times higher surface area (up to 251 m² g^?1), narrower pore size distribution, and significantly lower crystallization temperature than those obtained without any post‐synthesis treatment. To demonstrate the generality of the proposed strategy, a nearly identical post‐synthesis “water treatment” method is successfully used to prepare mesoporous monometallic (e.g., manganese oxide (MnO₂)) and bimetallic oxide (e.g., CuCo₂O₄ and MnCo₂O₄) nanospheres assembled of nanosheets or nanoplates with highly enhanced textural characteristics from the corresponding monometallic and bimetallic glycerate nanospheres, respectively. When evaluated as molybdenum (Mo) adsorbents for potential use in molybdenum‐99/technetium‐99m (⁹⁹Mo/^99mTc) generators, the treated mesoporous Al₂O₃ nanospheres display higher molybdenum adsorption performance than non‐treated Al₂O₃ nanospheres and commercial Al₂O₃, thereby suggesting the effectiveness of the proposed strategy for improving the functional performance of oxide materials. It is expected that the proposed method can be utilized to prepare other mesoporous metal oxides with enhanced textural characteristics and functional performance.     

Flexible Cationic Nanoparticles with Photosensitizer Cores for Multifunctional Biomedical Applications

One challenge for multimodal therapy is to develop appropriate multifunctional agents to meet the requirements of potential applications. Photodynamic therapy (PDT) is proven to be an effective way to treat cancers. Diverse polycations, such as ethylenediamine‐functionalized poly(glycidyl methacrylate) (PGED) with plentiful primary amines, secondary amines, and hydroxyl groups, demonstrate good gene transfection performances. Herein, a series of multifunctional cationic nanoparticles (PRP) consisting of photosensitizer cores and PGED shells are readily developed through simple dopamine‐involving processes for versatile bioapplications. A series of experiments demonstrates that PRP nanoparticles are able to effectively mediate gene delivery in different cell lines. PRP nanoparticles are further validated to possess remarkable capability of combined PDT and gene therapy for complementary tumor treatment. In addition, because of their high dispersities in biological matrix, the PRP nanoparticles can also be used for in vitro and in vivo imaging with minimal aggregation‐caused quenching. Therefore, such flexible nanoplatforms with photosensitizer cores and polycationic shells are very promising for multimodal tumor therapy with high efficacy.     

Immobilization of Photo‐Immunoconjugates on Nanoparticles Leads to Enhanced Light‐Activated Biological Effects

The past three decades have witnessed notable advances in establishing photosensitizer–antibody photo‐immunoconjugates for photo‐immunotherapy and imaging of tumors. Photo‐immunotherapy minimizes damage to surrounding healthy tissue when using a cancer‐selective photo‐immunoconjugate, but requires a threshold intracellular photosensitizer concentration to be effective. Delivery of immunoconjugates to the target cells is often hindered by I) the low photosensitizer‐to‐antibody ratio of photo‐immunoconjugates and II) the limited amount of target molecule presented on the cell surface. Here, a nanoengineering approach is introduced to overcome these obstacles and improve the effectiveness of photo‐immunotherapy and imaging. Click chemistry coupling of benzoporphyrin derivative (BPD)–Cetuximab photo‐immunoconjugates onto FKR560 dye‐containing poly(lactic‐co‐glycolic acid) nanoparticles markedly enhances intracellular photo‐immunoconjugate accumulation and potentiates light‐activated photo‐immunotoxicity in ovarian cancer and glioblastoma. It is further demonstrated that co‐delivery and light activation of BPD and FKR560 allow longitudinal fluorescence tracking of photoimmunoconjugate and nanoparticle in cells. Using xenograft mouse models of epithelial ovarian cancer, intravenous injection of photo‐immunoconjugated nanoparticles doubles intratumoral accumulation of photo‐immunoconjugates, resulting in an enhanced photoimmunotherapy‐mediated tumor volume reduction, compared to “standard” immunoconjugates. This generalizable “carrier effect” phenomenon is attributed to the successful incorporation of photo‐immunoconjugates onto a nanoplatform, which modulates immunoconjugate delivery and improves treatment outcomes.     

Nanoscale Lacing by Electrons

The ability to harness the optical or electrical properties of nanoscale particles depends on their assembly in terms of size and spatial characteristics which remains challenging due to lack of size focusing. Electrons provide a clean and focusing agent to initiate the assembly of nanoclusters or nanoparticles. Here an intriguing route is demonstrated to lace gold nanoclusters and nanoparticles in string assembly through electron‐initiated nucleation and aggregative growth of Au(I)‐thiolate motifs on a thin film substrate. This size‐focused assembly is demonstrated by controlling the electron dose under transmission electron microscopic imaging conditions. The Au(I)‐thiolate motifs, in combination with the molecularly mediated alignment, facilitate the interstring electrostatic and intrastring aurophilic interactions, which functions as a molecular template to aid electron‐initiated 1D lacing. The findings demonstrate a hierarchical route for the 1D assemblies with size and spatial tunable catalytic, optical, sensing, and diagnostic properties.     

Lighting Up MicroRNA in Living Cells by the Disassembly of Lock‐Like DNA‐Programmed UCNPs‐AuNPs through the Target Cycling Amplification Strategy

Intracellular microRNAs imaging based on upconversion nanoprobes has great potential in cancer diagnostics and treatments. However, the relatively low detection sensitivity limits their application. Herein, a lock‐like DNA (LLD) generated by a hairpin DNA (H1) hybridizing with a bolt DNA (bDNA) sequence is designed, which is used to program upconversion nanoparticles (UCNPs, NaYF₄@NaYF₄:Yb, Er@NaYF₄) and gold nanoparticles (AuNPs). The upconversion emission is quenched through luminescence resonance energy transfer (LRET). The multiple LLD can be repeatedly opened by one copy of target microRNA under the aid of fuel hairpin DNA strands (H2) to trigger disassembly of AuNPs from the UCNP, resulting in the lighting up of UCNPs with a high detection signal gain. This strategy is verified using microRNA‐21 as model. The expression level of microRNA‐21 in various cells lines can be sensitively measured in vitro, meanwhile cancer cells and normal cells can be easily and accurately distinguished by intracellular microRNA‐21 imaging via the nanoprobes. The detection limit is about 1000 times lower than that of the previously reported upconversion nanoprobes without signal amplification. This is the first time a nonenzymatic signal amplification method has been combined with UCNPs for imaging intracellular microRNAs, which has great potential for cancer diagnosis.