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Electrochemical production of hydrogen peroxide (H2 O2 ) through two-electron (2 e- ) oxygen reduction reaction (ORR) is an on-site and clean route. Oxygen-doped carbon materials with high ORR activity and H2 O2 selectivity have been considered as the promising catalysts, however, there is still a lack of direct experimental evidence to identify true active sites at the complex carbon surface. Herein, we propose a chemical titration strategy to decipher the oxygen-doped carbon nanosheet (OCNS900 ) catalyst for 2 e- ORR. The OCNS900 exhibits outstanding 2 e- ORR performances with onset potential of 0.825 V (vs. RHE), mass activity of 14.5 A g-1 at 0.75 V (vs. RHE) and H2 O2 production rate of 770 mmol g-1 h-1 in flow cell, surpassing most reported carbon catalysts. Through selective chemical titration of C=O, C-OH, and COOH groups, we found that C=O species contributed to the most electrocatalytic activity and were the most active sites for 2 e- ORR, which were corroborated by theoretical calculations.

Platinum is generally known as the most effective electrocatalyst for hydrogen evolution reaction because it can greatly lower the overpotential and accelerate the reaction kinetics, while its commercial potential always suffers from scarcity, high cost, low utilization, and poor durability particularly in acidic electrolytes. We herein demonstrate a facile method to improve the hydrogen evolution performance of Pt-based electrocatalysts by simply decorating the-state-of-the-art and commercially available Pt/C with hydrophobic protic ([DBU][NTf2]) or aprotic ([BMIm][NTf2]) ionic liquid. The current densities of [BMIm]@Pt/C and [DBU-H]@Pt/C with 10% ionic liquid at an overpotential of 40 mV are 2.81 and 4.15 times, respectively, higher than that of the pristine Pt/C. More importantly, ionic liquid-decoration significantly improves the long-term stability of Pt nanoparticles. After 8 h of chronoamperometric measurements, [DBU-H]@Pt/C and [BMIm]@Pt/C can still retain 83.7% and 78.3% of their original activity, respectively, which is much higher than that of the pristine Pt/C (24.4%). The improved performance of Pt/C decorated with ionic liquid is considered to arise from the improved proton conductivity (particularly for protic ionic liquid) and hydrophobic microenvironment created by the supported ionic liquid phase. The presence of ionic liquid layer not only de-coordinates H+ from hydronium ions nearby the Pt nanoparticles, but it also protects Pt nanoparticles from dissolution in the acidic media.

Highly efficient electrocatalysts towards hydrogen evolution reaction (HER) with large current density at all-pH values are critical for the sustainable hydrogen production. Herein, we report a free-standing HER electrode, phosphorous-doped molybdenum nitride nanoparticles embedded in 3-dimentional carbon nanosheet matrix (P-Mo2N-CNS) fabricated via one-step carbonization and in-situ formation. The as-prepared catalyst shows free-standing architecture with interconnected porous microstructure. P-doped Mo2N nanoparticles with an average diameter of 4.4 nm are well embedded in the 3-dimentional vertical carbon nanosheets matrix. Remarkable electrocatalytic HER performance is observed in alkaline, neutral and acidic media at large current densities. The overpotential of P-Mo2N-CNS to drive a current density of 100 mA cm−2 in 0.5 M H2SO4 and 1.0 M PBS is only 181 and 221 mV, respectively. In particular, the current density reaches up to 1000 mA cm−2 at a low overpotential of 256 mV in 1.0 M KOH, much better than that of the commercial Pt/C catalyst. Density functional theory calculations suggest the optimized H sorption kinetics on Mo2N after P doping, elucidating the superior activity.

Ruthenium (Ru)-based catalysts, with considerable performance and desirable cost, are becoming highly interesting candidates to replace platinum (Pt) in the alkaline hydrogen evolution reaction (HER). The hydrogen binding at Ru sites (Ru-H) is an important factor limiting the HER activity. Herein, density functional theory (DFT) simulations show that the essence of Ru-H binding energy is the strong interaction between the 4 d z 2 orbital of Ru and the 1s orbital of H. The charge transfer between Ru sites and substrates (Co and Ni) causes the appropriate downward shift of the 4 d z 2 -band center of Ru, which results in a Gibbs free energy of 0.022 eV for H* in the RuCo system, much lower than the 0.133 eV in the pure Ru system. This theoretical prediction has been experimentally confirmed using RuCo alloy-nanosheets (RuCo ANSs). They were prepared via a fast co-precipitation method followed with a mild electrochemical reduction. Structure characterizations reveal that the Ru atoms are embedded into the Co substrate as isolated active sites with a planar symmetric and Z-direction asymmetric coordination structure, obtaining an optimal 4 d z 2 modulated electronic structure. Hydrogen sensor and temperature program desorption (TPD) tests demonstrate the enhanced Ru-H interactions in RuCo ANSs compared to those in pure Ru nanoparticles. As a result, the RuCo ANSs reach an ultra-low overpotential of 10 mV at 10 mA cm-2 and a Tafel slope of 20.6 mV dec-1 in 1 M KOH, outperforming that of the commercial Pt/C. This holistic work provides a new insight to promote alkaline HER by optimizing the metal-H binding energy of active sites.

Electrocatalytic hydrogen evolution reaction (HER) in alkaline media is a promising electrochemical energy conversion strategy. Ruthenium (Ru) is an efficient catalyst with a desirable cost for HER, however, the sluggish H2O dissociation process, due to the low H2O adsorption on its surface, currently hampers the performances of this catalyst in alkaline HER. Herein, we demonstrate that the H2O adsorption improves significantly by the construction of Ru–O–Mo sites. We prepared Ru/MoO2 catalysts with Ru–O–Mo sites through a facile thermal treatment process and assessed the creation of Ru–O–Mo interfaces by transmission electron microscope (TEM) and extended X-ray absorption fine structure (EXAFS). By using Fourier-transform infrared spectroscopy (FTIR) and H2O adsorption tests, we proved Ru–O–Mo sites have tenfold stronger H2O adsorption ability than that of Ru catalyst. The catalysts with Ru–O–Mo sites exhibited a state-of-the-art overpotential of 16 mV at 10 mA cm–2 in 1 M KOH electrolyte, demonstrating a threefold reduction than the previous bests of Ru (59 mV) and commercial Pt (31 mV) catalysts. We proved the stability of these performances over 40 h without decline. These results could open a new path for designing efficient and stable catalysts.

Osteoporosis is a disease where increased bone weakness increases the risk of a broken bone. Until a broken bone occurs, there are typically no symptoms. Osteoporosis affects more than 75 million people in the United States, Europe and Japan. The diagnosis of osteoporosis is primarily determined by measuring bone mineral density using dual-energy X-ray absorptiometry, but for men under 50 years of age, premenopausal women should not be made on the basis of densitometric criteria alone. Bone biomarkers are a useful tool in detecting osteoporotic. A two-step dual-label time-resolved fluorescence immunoassay (TRFIA) was developed for the simultaneous detection of serum C-terminal telopeptide (β-CTX) and amino-terminal propeptide (P1NP) of Type I procollagen in a single run. The performance of this assay was first evaluated using clinical serum samples, and then compared with commercialized kits. The sensitivity of this assay for β-CTX was 1 ng/L (dynamic range, 0-1000 ng/L), and the sensitivity for P1NP detection was 1 μg/L (dynamic range, 1-1000 μg/L). High correlation coefficients (R) were obtained between the present dual-label TRFIA and commercially available kits (R = 0.99 for β-CTX and P1NP). The present dual-label TRFIA has high sensitivity, specificity and accuracy in clinical sample analysis. It is a good alternative to the single-label diagnostic methods.

The hemodialysis therapy is the primary treatment for the end-stage renal disease (ESRD) patients to extend their lives. To reduce the pathogenic infection during hemodialysis treatment, mussel-inspired polydopamine (PDA) was self-polymerized onto poly(ether sulfone) (PES) membranes to immobilize copper ions, because PDA coating could firmly adhere to the PES membranes and immobilize antimicrobial metal ions with its functional groups. The immobilized copper ions through PDA can penetrate deeply into the inner surface of the pores of PES membrane. Water permeability test further indicates PDA coating can obviously enhance the hydrophilicity of PES membranes. And copper ion immobilized PES membranes showed effective antibacterial activity with a relative safe release amount of copper ions (below 1 ppm). Furthermore, hemolysis test results revealed that PDA-assisted antibacterial PES membranes can relieve red blood cells damage compared to the pure PES membranes. To sum up, PES hemodialysis membranes obtained the antibacterial ability by the PDA-assisted copper ion immobilization, which can reduce the abuse of antibiotics and is beneficial to the patient suffering from kidney disease.

To improve the osteointegration property of biomedical titanium, nano-architectured electroactive coating was synthesized through the electrochemical polymerization of dopamine and pyrrole. The highly binding affinity of Ca2+ to the catechol moiety of doped dopamine enabled efficient interaction between polypyrrole/polydopamine nanowires and mineral ions. The results indicate that the PPy/PDA nanowires preserved its efficient electro-activity and accelerated the hydroxyapatite deposition in a simulated body fluid. The PPy/PDA nanowires coating could be applied to promote the osteointegration of titanium implant., Graphical abstract Image 1, Highlights • Nanowires were constructed through electrochemical polymerization of pyrrole and dapamine • The PPy/PDA nanowires possessed wonderful electroactivity. • The PPy/PDA nanowires could promote Hydroxyapatite formation.

Electrochemical carbon dioxide (CO2) reduction reaction (CO2RR) to obtain C2/multi-carbon fuels is an appealing technology to reduce carbon emission and store intermittent renewable electricity. The C–C coupling process, as the most critical step for generating C2/multi-carbon fuels, strongly depends on the concentration of *CO intermediates around the active sites. In this work, we prepared porous copper nanospheres (P-Cu) that greatly improved the C–C coupling process by enriching *CO intermediates in the pore structure. The specific pore features of P-Cu were characterized in detail by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption/desorption tests. Obviously, the P-Cu exhibits higher specific surface area and richer pore structure than the control sample compact copper nanosphere (C-Cu). The CO gas sensor and temperature programmed desorption (TPD) tests prove that the P-Cu has better CO adsorption and enrichment capacity than C-Cu due to the rich pore structure. As a result, P-Cu exhibited a high C2 selectivity with a Faradaic efficiency (FEC2) of 57.22% at −1.3 V (vs. RHE), which is about 2.5-fold than the C-Cu (FEC2 of 22.71%). This work provides an effective strategy to improve the activity and selectivity of C2 products in CO2RR by optimizing the adsorption/enrichment property of intermediates.

Construction of functional porous titanium scaffold is drawing ever growing attention, due to its effectiveness in solving the mechanical mismatch between titanium implant and bone tissue. However, the poor water permeability as well as the problem in achieving uniform surface modification inside scaffold hinders the further biomedical application of porous titanium scaffold. In this study, large-scale functional TiO2 nanostructures (nanonetwork, nanoplate and nanowire) were constructed on three-dimensional porous titanium scaffolds surface via an effective hydrothermal treatment method. These nanostructures increase the hydrophilicity of the titanium scaffold surface, facilitating the cell culture medium to penetrate into the inner pore of the scaffold. Zeta potential analyses indicate that the surface electrical properties depend on the nanostructure, with nanowire exhibiting the lowest potential at pH 7.4. The influence of the nano-functionalized scaffold on protein adsorption and cell adhesion was examined. The results indicate that the nano-functionalized surface could modulate protein adsorption and bone marrow derived mesenchymal stem cells (BMSCs) adhesion, with the nanowire functionalized porous scaffold homogeneously promoting protein adsorption and BMSCs adhesion. Our research will facilitate future research on the development of novel functional porous scaffold.

Mineralization plays a crucial role in the formation and remodeling of bone and charge has a positive influence on the mineralization by manipulating apatite deposition. In this paper, micropatterned piezoelectric K0.5Na0.5NbO3 (MPK) was constructed via laser-irradiation induced micro-zonal phase transition to manipulate set-selective apatite deposition. Two types of piezoelectric micro-zones on polarized MPK showed different charge densities, namely, higher charge density zone (H-zone) and lower charge density zone (L-zone). The micro-zonal piezoelectric difference on negatively polarized MPK (N-MPK) was ascertained by scanning Kelvin probe force microscopy (SKPM). With the manipulation of spatial charge, apatite selectively deposited on H-zone rather than L-zone, forming stripped zonal distribution. The furry platelet morphology of apatite was observed by scanning electron microscopy (SEM). Energy-dispersive spectroscopy (EDS) mapping observation indicated selective distribution of Ca and P elements in apatite. Phase composition of deposited apatite also can be regulated effectively via X-ray diffraction (XRD), which confirmed the existence of hydroxyapatite phase. Meanwhile, the apatite was further identified as carbonated hydroxyapatite by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The feasible and convenient way of manipulating apatite deposition selectively with spatial charge realized by micro-zonal piezoelectric materials will inspire future development in biomimetic materials designation for biomedical applications.

Neural stem cell (NSC) transplantation exerts a therapeutic effect on spinal cord injury (SCI) but is limited to an unregulated differentiation pattern by which NSCs preferentially differentiate into astrocytes, with relatively few neurons. It is well established that the increased NSC-derived astrocytes exhibit aberrant axonal sprouting associated with allodynia-like symptoms of the forepaws. Some strategies have been used to overcome this issue, such as regulation of major pathways, ex vivo gene transfer, and genetic overexpression. However, lack of efficiency, viral vector safety issues and the risk of tumorigenesis have hindered the clinical application of these treatments. Here, we show that astrocytic differentiation of NSCs in vitro and in vivo can be inhibited by encapsulation of cells in a three-dimensional chondroitin sulfate methacrylate (CSMA) hydrogel. When CSMA hydrogels were used to transplant NSCs, the combinatory implant promoted functional recovery and attenuated the hypersensitivity responses of the forepaws. Further analysis showed that transplantation of NSCs within CSMA hydrogels reduced injured cavity areas and promoted neurogenesis rather than fibroglial formation after graft implantation. Furthermore, the treatment prevented allodynia-related CGRP/GAP43-positive nociception due to fibers sprouting into inappropriate lamina regions. Taken together, these findings show that CSMA/NSCs combined transplantation helps prevent adverse side effects of NSCs treatment and promotes recovery of SCI.

Curzerene is a sesquiterpene and component used in oriental medicine. It was originally isolated from the traditional Chinese herbal medicine Curcuma rhizomes. In this study, anticancer activity of curzerene was examined in both in vitro and in vivo models. The result of the MTT assay showed that curzerene exhibited antiproliferative effects in SPC-A1 human lung adenocarcinoma cells in a time-dependent and dose-dependent manner. The anticancer IC50s were 403.8, 154.8, and 47.0 µM for 24, 48, and 72 hours, respectively. The flow cytometry analysis indicated curzerene arrested the cells in the G2/M cell cycle and promoted or induced apoptosis of SPC-A1 cells. The percentage of cells arrested in the G2/M phase increased from 9.26 % in the control group cells to 17.57 % in the cells treated with the highest dose (100 µM) of curzerene. Western blot and RT-PCR analysis demonstrated that curzerene induced the downregulation of GSTA1 protein and mRNA expressions in SPC-A1 cells. Tumor growth was significantly inhibited in SPC-A1 cell-bearing nude mice by using curzerene (135 mg/kg daily), meanwhile, curzerene did not significantly affect body mass and the organs of the mice, which may indicate that curzerene has limited toxicity and side effects in vivo. In conclusion, curzerene could inhibit the proliferation of SPC-A1 human lung adenocarcinoma cells line in both in vitro and in vivo models. Focusing on its relationship with GSTA1, curzerene could induce the downregulation of GSTA1 protein and mRNA expressions in SPC-A1 cells. Curzerene might be used as an anti-lung adenocarcinoma drug candidate compound for further development.

In this work, we designed and synthesized N-(2-[18F]-flouroptopionyl)-l-arginine ([18F]FPARG), which was an analogue of l-arginine for tumor positron emission tomography (PET) imaging. Semi-automated radiosynthesis of [18F]FPARG was performed from the reaction of l-arginine with 4-nitropheyl-2-[18F]flouropropionate ([18F]NFP) by multi-step procedure on the modified PET-MF-2V-IT-1 synthesizer. The uncorrected radiochemical yield of [18F]FPARG was 15 ± 3 % (n = 10) with more than 98 % radiochemical purity. The small-animal PET/CT fused imaging showed that liver and urinary bladder were the primary excretion route of this tracer.

The development of both H2–O2 proton exchange membrane fuel cells (PEMFCs) and Zn-air batteries are challenged by high-efficiency air cathodes with a high oxygen reduction reaction (ORR) electrocatalytic-activity. The increase of density and accessibility of active sites are widely accepted effective approach to boost the oxygen reduction reaction. In this work, we develop a template-free g-C3N4-assisted pyrolysis strategy to transform ZIF-8 polyhedrons to hierarchically open-porous carbon networks incorporated exclusive Fe–Nx active sites. Due to the integration of high specific surface area, highly open porous architecture with meso/micro-pores, and high-density Fe-Nx active species, the electro-catalysis performance of optimal catalysts exceed commercial Pt/C in alkaline solution, and is comparable to that of commercial Pt/C in acidic solution, which is one of the best recently reported carbon-based electrocatalysts. Impressively, when it is used as an air cathode catalyst, it achieves a high power density of 481 mW·cm−2 in acidic H2–O2 proton exchange membrane fuel cell (PEMFC) and an excellent performance in the alkaline Zn–air battery (a high power density of 121 mW·cm−2).

Mimicking soft tissue mechanical properties and the high conductivity required for electrical transmission in the native spinal cord is critical in nerve tissue regeneration scaffold designs. However, fabricating scaffolds of high conductivity, tissue-like mechanical properties, and excellent biocompatibility simultaneously remains a great challenge. Here, a soft, highly conductive, biocompatible conducting polymer hydrogel (CPH) based on a plant-derived polyphenol, tannic acid (TA), cross-linking and doping conducting polypyrrole (PPy) chains is developed to explore its therapeutic efficacy after a spinal cord injury (SCI). The developed hydrogels exhibit an excellent electronic conductivity (0.05-0.18 S/cm) and appropriate mechanical properties (0.3-2.2 kPa), which can be achieved by controlling TA concentration. In vitro, a CPH with a higher conductivity accelerated the differentiation of neural stem cells (NSCs) into neurons while suppressing the development of astrocytes. In vivo, with relatively high conductivity, the CPH can activate endogenous NSC neurogenesis in the lesion area, resulting in significant recovery of locomotor function. Overall, our findings evidence that the CPHs without being combined with any other therapeutic agents have stimulated tissue repair following an SCI and thus have important implications for future biomaterial designs for SCI therapy.