Dual-functional lanthanide-MOF probe nanocomposite based on hydroxyapatite nanowires as fluorescent sensor for ascorbic acid.

A dual-functional lanthanide-MOF nanocomposite probe was designed and constructed for the detection of ascorbic acid (AA). The magnetically functionalized hydroxyapatite nanowires are selected as the carriers and simultaneously loaded with ciprofloxacin (CIP) and terbium metal organic framework to form the internal reference fluorescence probe nanocomposite (Fe3O4-HAPNWs-Tb/MOF-CIP). This dual-functional lanthanide-MOF probe not only combines the respectively unique fluorescence properties of lanthanide MOFs and CIP, but also takes full advantage of the rapid separation properties of the magnetic component. Structural and spectroscopic characterization results have demonstrated the successful synthesis of probe material and the fluorescence mechanism. At a suitable excitation wavelength (295 nm), the probe can simultaneously emit characteristic fluorescence of CIP (445 nm) and Tb3+ (543 nm). In the presence of AA, the ratio of I543/I445 decreases rapidly with increasing of AA concentration. The linear range of determination is 0.3-40 µM with a detection limit of 20.4 nM. The contents of AA in vitamin C tablets and four fruit juice samples were detected by the composite probe. The spiked recoveries ranged from 82.6 to 104.2% with relative standard deviations (RSD) less than 2.1%, revealing the practical application value of the developed sensor in healthcare and food fields. A novel internal reference fluorescence sensor (Fe O -HAPNWs-Tb/MOF-CIP) was constructed for detecting ascorbic acid by solvothermal and self-assembly techniques, showing excellent selectivity and sensitivity based on the different responses of Tb/MOF and CIP to the target.

Impermeable Atomic Layer Deposition for Sputtering Buffer Layer in Efficient Semi-Transparent and Tandem Solar Cells via Activating Unreactive Substrate.

Atomic layer deposition (ALD) turns out to be particularly attractive technology for the sputtering buffer layer when preparing the semi-transparent (ST) perovskite solar cells (PSCs) and the tandem solar cells. ALD process turns to be island growth when the substrate is unreactive with the ALD reactants, resulting in the pin-hole layer, which causes an adverse effect on anti-sputtering. Here, p-i-n structured PSCs with ALD SnOx as sputtering buffer layer are conducted. The commonly used electron transportation layer (ETL) PCBM in the p-i-n structured PVK solar cell is an unreactive substrate that prevents the layer-by-layer growth for the ALD SnOx . PCBM layer is activated by introducing reaction sites to form impermeable ALD layers. By introducing reaction sites/ALD SnOx as sputtering buffer layer, the authors succeed to fabricate ST-PSCs and perovskite/silicon (double-side polished) tandem solar cells with power conversion efficiency (PCE) of 20.25% and 23.31%, respectively. Besides, the unencapsulated device with reaction sites maintains more than 99% of the initial PCE after aging over 5100 h. This work opens a promising avenue to prepare impermeable layer for stable PSCs, ST-PSCs, tandem solar cells, and the related scale-up solar cells.

Carbon dots-decorated hydroxyapatite nanowires-lanthanide metal-organic framework composites as fluorescent sensors for the detection of dopamine.

In this work, carbon dots-decorated hydroxyapatite nanowires-lanthanide metal-organic framework composites were designed and synthesized as ratiometric fluorescent probes for the detection of dopamine. The as-prepared HAPNWs-CDs-Tb/MOF were characterized by TEM, FE-SEM, and FT-IR spectral analysis, illustrating that the HAPNWs-CDs-Tb/MOF comprised hydroxyapatite nanowires that acted as a carrier to form a spinning structure of the lanthanide MOF that was decorated with carbon dots. The as-prepared HAPNWs-CDs-Tb/MOF were luminescent with the green fluorescence of Tb3+ at 543 nm and the blue fluorescence of the CDs at 426 nm as the signal response groups for the detection of DA. The sensor could detect DA in the concentration range of 0-180 µM, with a linear range of 0.04-20 µM and detection limit of 12.26 nM. The method was successfully applied to the detection of DA in human serum. The spiked recoveries were 100.8%-103.3% and the relative standard deviation (RSD) was 3.82%.

Facile synthesis MnCo2O4.5@C nanospheres modifying PbO2 energy-saving electrode for zinc electrowinning.

The oxygen evolution reaction kinetics in industrial zinc electrowinning is sluggish, resulting in low electrocatalytic activity and substantial energy expenditure (about one-third of energy was wasted due to the strong polarization effect). Herein, the paper described a core-shell structured MnCo2O4.5@C modified PbO2 electrode through the pyrolysis and co-electrodeposition as a promising candidate for zinc electrowinning. As a result, the obtained Pb-0.2%Ag/α-PbO2/ß-PbO2-MnCo2O4.5@C composite electrode showed a sandwich-like structure, where Pb-0.2%Ag as a core, α-PbO2 as a mid-layer, and ß-PbO2-MnCo2O4.5@C served as an electrocatalytic layer. It also possessed improved OER catalytic activity, only required 680 mV to achieve a current density of 50 mA cm-2 and a Tafel slope of 216.04 mV dec-1 in an acidic solution containing 50 g L-1 Zn2+ and 150 g L-1 H2SO4. The current efficiency increased by 0.7% and the cell voltage reduced by 360 mV as compared to a conventional Pb-0.76%Ag alloy electrode, leading to a remarkable energy-consumption reduction of 283.5 kW h for producing per ton metallic zinc. Furthermore, Pb-0.2%Ag/α-PbO2/ß-PbO2-MnCo2O4.5@C exhibited a prolonged service life, which worked about 44 h under an ultra-high current density of 2 A cm-2. Hence, this paper provides the strategy to design and construct non-precious, high-performance catalyst for electrolysis and other applications.

Preparation of carbon dots-doped terbium phosphonate coordination polymers as ratiometric fluorescent probe for citrate detection.

In this work, carbon dots-doped terbium phosphonate coordination polymers (CDs-GMP/Tb) were designed and prepared as ratiometric fluorescent probes for the detection of citrate. The as-prepared CDs-GMP/Tb are prepared and have the merits of high photostability, low toxicity, and excellent biocompatibility. The as-prepared CDs-GMP/Tb as ratiometric fluorescent probes also have better anti-interference ability and stability compared with the traditional single fluorescent probe. The surface morphology, fabrication, and spectroscopy were characterized through a variety of instruments. It confirms that the probes exhibited network structure doping carbon dots. With the addition of citrate, the fluorescence of GMP/Tb at 545 nm was significantly quenched, contrasting to the enhancement of fluorescence of CDs at 454 nm. Under optimum conditions, the detection limit for citrate was 0.47 µM, with a linear range of 0-200 µM between citrate concentrations and I545/I454. It has high sensitivity, selective, and rapid detection for citrate. The as-prepared CDs-GMP/Tb as ratiometric fluorescent probes were also used for imaging citrate in living cells. These experiment results showed that CDs-GMP/Tb as ratiometric fluorescent probes could be applied to trace citrate detection in the environmental and biological fields.

α(ß)-PbO2 doped with Co3O4 and CNT porous composite materials with enhanced electrocatalytic activity for zinc electrowinning.

The high energy consumption during zinc electrowinning is mainly caused by the high overpotential of the oxygen evolution for Pb-Ag alloys with strong polarization. The preparation of new active energy-saving materials has become a very active research field, depending on the synergistic effects of active particles and active oxides. In this research, a composite material, α(ß)-PbO2, doped with Co3O4 and CNTs on the porous Ti substrate was prepared via one-step electrochemical deposition and the corresponding electrochemical performance was investigated in simulated zinc electrowinning solution. The composite material showed a porous structure, finer grain size and larger electrochemical surface area (ECSA), which indicated excellent electrocatalytic activity. Compared with the Pb-0.76 wt% Ag alloy, the overpotential of oxygen evolution for the 3D-Ti/PbO2/Co3O4-CNTs composite material was decreased by about 452 mV under the current density of 500 A m-2 in the simulated zinc electrowinning solution. The decrease in the overpotential of oxygen evolution was mainly ascribed to the higher ECSA and lower charger transfer resistance. Moreover, it showed the lowest self-corrosion current density of 1.156 × 10-4 A cm-2 and may be an ideal material for use in zinc electrowinning.

Multiporous Terbium Phosphonate Coordination Polymer Microspheres as Fluorescent Probes for Trace Anthrax Biomarker Detection.

Lanthanide coordination polymers have been recently regarded as attractive sensing materials because of their selectivity, high sensitivity, and rapid response ability. In this research, the multiporous terbium phosphonate coordination polymer microspheres (TbP-CPs) were prepared as a novel fluorescent probe, which showed a fluorescence turn-on response capability for the detection of the trace anthrax biomarker dipicolinate acid (DPA). The morphology and chemical composition of as-prepared TbP-CPs were characterized in detail. The TbP-CPs have the vegetable-flower-like structure and microporous surface. In addition, the as-prepared TbP-CPs not only possess the merits of convenience and simple preparation with high yield but also have the excellent characters as fluorescent probes, such as high stability, good selectivity, and rapid detection ability within 30 s. This proposed sensor could detect DPA with a linear relationship in concentrations ranging from 0 to 8.0 µM and a high detection sensitivity of 5.0 nM. Furthermore, the successful applications of DPA detection in urine and bovine serum were demonstrated. As a result, the recovery ranged from 93.93-101.6%, and the relative standard deviations (RSD) were less than 5%.

Electrochemical fabrication of FeS x films with high catalytic activity for oxygen evolution.

Electrochemical decomposition of water to produce oxygen (O2) and hydrogen (H2) through an anodic oxygen evolution reaction (OER) and a cathodic hydrogen evolution reaction (HER) is a promising green method for sustainable energy supply. Here, we demonstrate that cauliflower-like S-doped iron microsphere films are materials that can efficiently decompose water as an electrocatalyst for the oxygen evolution reaction. FeS x films are prepared by a simple one-step electrodeposition method and directly grow on copper foam from a deep eutectic solvent, ethaline (mixture of choline chloride and ethylene glycol), as a durable and highly efficient catalyst for the OER in 1.0 M KOH. The prepared FeS x /CF, as an oxygen-evolving anode, shows remarkable catalytic performance toward the OER with a moderate Tafel slope of 105 mV dec-1, and require an overpotential of only 340 mV to drive a geometrical catalytic current density of 10 mA cm-2. In addition, this catalyst also demonstrates strong long-term electrochemical durability. This study provides a simple synthesis route for practical applications of limited transition metal nano catalysts.

Overhang molecular beacons encapsulated in tethered cationic lipoplex nanoparticles for detection of single-point mutation in extracellular vesicle-associated RNAs.

Detection of specific extracellular RNAs has been developed for non-invasive cancer diagnosis. However, accurate and efficient identification of RNAs with single-point mutation in cancer cells-derived extracellular vesicles (EVs) is challenging. Herein, we present a unique overhang molecular beacon with internal dye (Ohi-MB) with a stable hairpin structure, fast hybridization kinetics and single mismatch specificity. Ohi-MBs are encapsulated in cationic lipoplex nanoparticles (CLNs) that are tethered on a gold coated glass slide as a chip, which can capture circulating EVs and detect encapsulated target RNAs in-situ in a single step. The capability of detection of single-point mutation by CLN-Ohi-MB is demonstrated in artificial EVs and cancer cells. This CLN-Ohi-MB biochip could quantify single-point mutations in KRAS mRNA (G12C, G12D, G12V) in pancreatic cancer cell-derived EVs and single-point mutations in EGFR mRNA (L858R and T790M) in lung cancer cell-derived EVs with high specificity, not achievable by conventional molecular probes. We show that CLN-Ohi-MB biochip could selectively and sensitively identify single-point mutations in KRAS mRNA in human serum EVs, distinguishing pancreatic cancer patients with different mutations.

Long Circulating Polymeric Nanoparticles for Gene/Drug Delivery.

BACKGROUND: The prolonged circulation time of nanoparticles in the blood is a prerequisite to realize a controlled and targeted (passive or active targeting) release of the encapsulated gene/drug at the desired site of action. The most popular method to mask or camouflage nanoparticles is the adsorbed, grafted or conjugated of poly (ethylene glycol) (PEG) or other hydrophilic polymers (e.g. polysaccharides) to the particle surface. However, the circulation half-life of nanoparticles still cannot satisfy the need of clinical use. METHOD: This review focuses on several recent advances in the design and fabrication of polymeric nanoparticles with long circulating characters in blood. The factors influencing the physicochemical characteristics of nanoparticle surface and its surface modification have been discussed. RESULTS: Gene/drug carriers can also be combined with functionalized physical, chemical or biological stimuli to improve passive and active targeting strategies. The choice of suitable manufacturing technique of polymeric nanoparticles depends on the gene/drug to be encapsulated in the particle, the physicochemical properties of the polymer, their therapeutic goal to be reached and the scalability of the fabrication which allows for a clinical realization of the most promising nanomedicines. The factors influencing long circulating properties of nanoparticles are mainly particle size, surface charge and hydrophilicity. Surface modification of polymeric nanoparticles has been focused on PEG, polysaccharides, and so on. CONCLUSION: Identification of novel potential coating materials with satisfied characters is an emerging field of interest in the design of long circulating polymer-based nanoparticulate gene/drug delivery.

A signal-amplifiable biochip quantifies extracellular vesicle-associated RNAs for early cancer detection.

Detection of extracellular vesicle (EV)-associated RNAs with low expression levels in early-stage cancer remains a challenge and is highly valuable. Here, we report a nanoparticle-based biochip that could capture circulating EVs without isolation, brighten encapsulated RNAs, and amplify fluorescence signals in situ in a single step. We confine catalyzed hairpin DNA circuit (CHDC) in cationic lipid-polymer hybrid nanoparticles (LPHNs) that are tethered on a chip. LPHN features a core-shell-corona structure that facilitates the transfer and mixing of CHDC with EV-associated RNAs when forming the LPHN-EV nanocomplex. CHDC is triggered upon target RNA binding and quickly generate amplified signals. The signal amplification efficiency of LPHN-CHDC is demonstrated in artificial EVs, cancer cells, and cancer cell-derived EVs. We show that LPHN-CHDC biochip with signal amplification capability could selectively and sensitively identify low expression glypican-1 mRNA in serum EVs, distinguishing patients with early- and late-stage pancreatic cancer from healthy donors and patients with benign pancreatic disease.

Quantitative analysis of thymine with surface-enhanced Raman spectroscopy and partial least squares (PLS) regression.

Silver sol surface-enhanced Raman spectroscopy (SERS) was considered as a technique in the quantitative analysis of low-concentration thymine. Because of the poor stability and reproducibility of SERS signal, a polymer of polyacrylic acid sodium was selected as a stable medium to add into silver sol in order to obtain a surface-enhanced Raman spectroscopy signal. Assignments of Raman shift for solid thymine, SERS of thymine, and SERS of thymine containing stable medium were given. The comparison of Raman peaks between them showed that the addition of stable medium had a little influence on the SERS of thymine and is suitable for the quantitative analysis of low-concentration thymine.