Design of robust superhydrophobic surfaces.

The ability of superhydrophobic surfaces to stay dry, self-clean and avoid biofouling is attractive for applications in biotechnology, medicine and heat transfer1-10. Water droplets that contact these surfaces must have large apparent contact angles (greater than 150 degrees) and small roll-off angles (less than 10 degrees). This can be realized for surfaces that have low-surface-energy chemistry and micro- or nanoscale surface roughness, minimizing contact between the liquid and the solid surface11-17. However, rough surfaces-for which only a small fraction of the overall area is in contact with the liquid-experience high local pressures under mechanical load, making them fragile and highly susceptible to abrasion18. Additionally, abrasion exposes underlying materials and may change the local nature of the surface from hydrophobic to hydrophilic19, resulting in the pinning of water droplets to the surface. It has therefore been assumed that mechanical robustness and water repellency are mutually exclusive surface properties. Here we show that robust superhydrophobicity can be realized by structuring surfaces at two different length scales, with a nanostructure design to provide water repellency and a microstructure design to provide durability. The microstructure is an interconnected surface frame containing 'pockets' that house highly water-repellent and mechanically fragile nanostructures. This surface frame acts as 'armour', preventing the removal of the nanostructures by abradants that are larger than the frame size. We apply this strategy to various substrates-including silicon, ceramic, metal and transparent glass-and show that the water repellency of the resulting superhydrophobic surfaces is preserved even after abrasion by sandpaper and by a sharp steel blade. We suggest that this transparent, mechanically robust, self-cleaning glass could help to negate the dust-contamination issue that leads to a loss of efficiency in solar cells. Our design strategy could also guide the development of other materials that need to retain effective self-cleaning, anti-fouling or heat-transfer abilities in harsh operating environments.

Zcf24, a zinc-finger transcription factor, is required for lactate catabolism and inhibits commensalism in Candida albicans.

Candida albicans is a normal resident of humans and also a prevalent fungal pathogen. Lactate, a nonfermentative carbon source available in numerous anatomical niches, can be used by C. albicans as a carbon source. However, the key regulator(s) involved in this process remain unknown. Here, through a genetic screen, we report the identification of a transcription factor Zcf24 that is specifically required for lactate utilization in C. albicans. Zcf24 is responsible for the induction of CYB2, a gene encoding lactate dehydrogenase that is essential for lactate catabolism, in response to lactate. Chromatin immunoprecipitation showed a significantly higher signal of Zcf24 on the CYB2 promoter in lactate-grown cells than that in glucose-grown cells. Genome-wide transcription profiling indicates that, in addition to CYB2, Zcf24 regulates genes involved in the ß-oxidation of fatty acids, iron transport, and drug transport. Surprisingly, deleting ZCF24 confers enhanced commensal fitness. This could be attributed to Crz1-activated ß-glucan masking in the zcf24 mutant. The orthologs of Zcf24 are distributed in species most closely to C. albicans and some filamentous fungal species. Altogether, Zcf24 is the first transcription factor identified to date that regulates lactate catabolism in C. albicans and it is also involved in the regulation of commensalism.

Investigating Shear Stress of Ice Accumulated on Surfaces with Various Roughnesses: Effects of a Quasi-Water Layer.

The investigation of the anti-icing/deicing is essential because the icing phenomenon deteriorates the natural environment and various projects. By conducting molecular dynamics simulation, this work analyzes the effect of the quasi-water layer on the ice shear stress over smooth and rough surfaces, along with the underlying physics of the quasi-water layer. The results indicate that the thickness of the quasi-water layer monotonically increases with temperature, resulting in a monotonic decrease in the ice shear stress on the smooth surface. Due to the joint effects of the smooth surface wettability and the quasi-water layer, the ice shear stress increases and then decreases to almost a constant value when the surface changes from a hydrophobic to a hydrophilic one. For rough surfaces with stripe nanostructures, when the width of the bump for one case equals the depression for the other case, the variations of shear stress with height for these two cases are almost the same. The rough surface is effective in reducing the ice shear stress compared to the smooth surface due to the thickening of the quasi-water layer. Each molecule in the quasi-water layer and its four nearest neighboring molecules gradually form a tetrahedral ice-like structure along the direction away from the surface. The radial distribution function also shows that the quasi-water layer resembles the liquid water rather than the ice structure. These findings shed light on developing anti-icing and deicing techniques.

PAM-independent ultra-specific activation of CRISPR-Cas12a via sticky-end dsDNA.

Although CRISPR-Cas12a [clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 12a] combining pre-amplification technology has the advantage of high sensitivity in biosensing, its generality and specificity are insufficient, which greatly restrains its application range. Here, we discovered a new targeting substrate for LbaCas12a (Lachnospiraceae bacterium Cas12a), namely double-stranded DNA (dsDNA) with a sticky-end region (PAM-SE+ dsDNA). We discovered that CRISPR-Cas12a had special enzymatic properties for this substrate DNA, including the ability to recognize and cleave it without needing a protospacer adjacent motif (PAM) sequence and a high sensitivity to single-base mismatches in that substrate. Further mechanism studies revealed that guide RNA (gRNA) formed a triple-stranded flap structure with the substrate dsDNA. We also discovered the property of low-temperature activation of CRISPR-Cas12a and, by coupling with the unique DNA hybridization kinetics at low temperature, we constructed a complete workflow for low-abundance point mutation detection in real samples, which was fast, convenient and free of single-stranded DNA (ssDNA) transformation. The detection limits were 0.005-0.01% for synthesized strands and 0.01-0.05% for plasmid genomic DNA, and the mutation abundances provided by our system for 28 clinical samples were in accordance with next-generation sequencing results. We believe that our work not only reveals novel information about the target recognition mechanism of the CRISPR-Cas12a system, but also greatly broadens its application scenarios.

Ultrasensitive and Quantitative DNA Methylation Detection Method Based on the MutS Protein.

DNA methylation is closely related to cancer. It is generally accepted that DNA methylation detection is crucial in cancer diagnosis, prognosis, and treatment monitoring. Therefore, there is an urgent demand for developing a simple, rapid, highly sensitive, and highly specific methylation detection method to detect DNA methylation at specific sites quantitatively. In this work, we introduce a DNA methylation detection method based on MutS and methylation-specific PCR, named MutS-based methylation-specific PCR (MB-MSP), which has the advantages of simplicity, speed, high specificity, sensitivity, and broad applicability. Utilizing the MutS's ability to bind mismatched base pairs, we inhibit not only the amplification of unmethylated DNA but also nonspecific primer amplification. We achieved a detection sensitivity of 0.5% for the methylated genes of ACP1, CLEC11A, and SEPT9 by MB-MSP. It has a good linear relationship and a detection time of only 1.5 h. To validate the feasibility of the MB-MSP method in clinical application, we conducted methylation detection on plasma-circulating tumor DNA samples from 10 liver cancer patients and 5 healthy people, achieving a 100% accuracy rate. In conclusion, MB-MSP, as a novel and reliable DNA methylation detection tool, holds significant application value and potential for advancing early cancer diagnosis.

Efg1 and Cas5 Orchestrate Cell Wall Damage Response to Caspofungin in Candida albicans.

Echinocandins are recommended as the first-line drugs for the treatment of systemic candidiasis. Cas5 is a key transcription factor involved in the response to cell wall damage induced by echinocandins. In this study, through a genetic screen, we identified a second transcription factor, Efg1, that is also crucial for proper transcriptional responses to echinocandins. Like CAS5, deletion of EFG1 confers hypersensitivity to caspofungin. Efg1 is required for the induction of CAS5 in response to caspofungin. However, ectopically expressed CAS5 cannot rescue the growth defect of efg1 mutant in caspofungin-containing medium. Deleting EFG1 in the cas5 mutant exacerbates the cell wall stress upon caspofungin addition and renders caspofungin-resistant Candida albicans responsive to treatment. Genome-wide transcription profiling of efg1/efg1 and cas5/cas5 using transcriptome sequencing (RNA-Seq) indicates that Efg1 and Cas5 coregulate caspofungin-responsive gene expression, but they also independently control induction of some genes. We further show that Efg1 interacts with Cas5 by yeast two-hybrid and in vivo immunoprecipitation in the presence or absence of caspofungin. Importantly, Efg1 and Cas5 bind to some caspofungin-responsive gene promoters to coordinately activate their expression. Thus, we demonstrate that Efg1, together with Cas5, controls the transcriptional response to cell wall stress induced by caspofungin.

Inhibiting Fungal Echinocandin Resistance by Small-Molecule Disruption of Geranylgeranyltransferase Type I Activity.

Echinocandin resistance in Candida is a great concern, as the echinocandin drugs are recommended as first-line therapy for patients with invasive candidiasis. However, therapeutic efforts to thwart echinocandin resistance have been hampered by a lack of fungal specific drug targets. Here, we show that deleting CDC43, the ß subunit of geranylgeranyltransferase type I (GGTase I), confers hypersensitivity to echinocandins, which renders GGTase I a tractable target in combatting echinocandin resistance. The membrane localization of Rho1, which is critical for (1,3)-ß-d-glucan synthase Fks1 activation, is disrupted in the cdc43 mutant, resulting in decreased amounts of glucans in the cell wall, thereby exacerbating the cell wall stress upon caspofungin addition. Guided by this insight, we found that selective chemical inhibition of GGTase I by L-269289 potentiates echinocandin activity and renders echinocandin-resistant Candida albicans responsive to treatment in vitro and in animal models for disseminated infection. Furthermore, L-269289 and echinocandins also act in a synergistic manner for the treatment of Candida tropicalis and Candida parapsilosis Importantly, deletion of CDC43 is lethal in Candida glabrata L-269289 is active on its own to kill C. glabrata, and its fungicidal activity is enhanced when combined with caspofungin. Thus, targeting GGTase I has therapeutic potential to address the clinical challenge of echinocandin-resistant candidiasis.

Surface charge printing for programmed droplet transport.

The directed, long-range and self-propelled transport of droplets on solid surfaces is crucial for many applications from water harvesting to bio-analysis1-9. Typically, preferential transport is achieved by topographic or chemical modulation of surface wetting gradients that break the asymmetric contact line and overcome the resistance force to move droplets along a particular direction10-16. Nonetheless, despite extensive progress, directional droplet transport is limited to low transport velocity or short transport distance. Here we report the high-velocity and ultralong transport of droplets elicited by surface charge density gradients printed on diverse substrates. We leverage the facile water droplet printing on superamphiphobic surfaces to create rewritable surface charge density gradients that stimulate droplet propulsion under ambient conditions17 and without the need for additional energy input. Our strategy provides a platform for programming the transport of droplets on flat, flexible and vertical surfaces that may be valuable for applications requiring a controlled movement of droplets17-19.

Surface-Charge-Assisted Microdroplet Generation on a Superhydrophobic Surface.

The ability to generate and manipulate droplets down to microscales has attracted great attention in a variety of applications, such as in printing, microreactors, and biological assays. However, the production of microdroplets is often limited by special equipment or the size of needles. Here, an unexplored and facile approach is demonstrated; microdroplets can be generated and trapped yet not pinned on a micro-nano-structured superhydrophobic surface by controllable surface charge during drop impact. Tiny droplets with a size at a scale of tens of microns to millimeters are generated by simply changing the impacting velocity, the size of the impact drop, or impact frequency. Theoretical analysis suggests the generation of the microdroplet as a result of the surface-charge-regulated adhesion, competing with liquid dynamic and interfacial energy. The distribution of surface charge which determines the size and the location of the microdroplet is at the top of the micro-nano-structured surface and dependent on the pressure field applied on the surface during the drop impact. The mobility of the resulting microdroplet that can be easily manipulated without liquid retention is also shown, by taking advantage of the shielding property of the surface charge. This facile yet effective method provides a promising candidate for the realization of tiny droplet-generating and -manipulating applications.

Enhanced nano-aerosol loading performance of multilayer PVDF nanofiber electret filters.

Aerosol loading behavior of PVDF nanofiber electret filters using neutrally charged nano- and submicron aerosols was investigated experimentally for the first time. The loading behavior include variations of filtration efficiency and pressure drop and distribution of deposited aerosols in the filters all having the same fiber basis weight (3.060 gsm). Through the filtration efficiency variations of uncharged/charged, single-/multi-layer filters with aerosol loading, it was observed that mechanical PVDF filters had continuously increasing filtration efficiency, while PVDF electret filters had initially decreasing and subsequently increasing filtration efficiency until reaching 100% due to diminishing electrostatic effect and enhancing mechanical effect. By combining the pressure drop evolution of different filters during aerosol loading and detailed SEM images of the loaded filters, we have demonstrated that multilayer PVDF filters, especially the electret ones, could significantly slow down the pace of filter clogging (skin effect) and increase significantly the aerosol holding capacity during depth filtration. Generally, the multilayer nanofiber filters received the most aerosol deposit during depth filtration, whereas the single-layer nanofiber filters with the same basis weight of fibers received the most deposit during cake filtration. The multilayer nanofiber filters had approximately 70% aerosol deposit in the filter during depth filtration fully utilizing the full filter thickness, especially for the electret filters that had charged fibers, and only 30% deposit in the cake. On the contrary, the single-layer uncharged/charged nanofiber filters were exactly the reverse due to persistency of the skin effect with only 30% deposit in the filter mostly located in the upstream layer, yet 70% deposit in the cake. During depth filtration, the pressure drop per added mass deposit for the multilayer electret filter was very low at 11 Pa gsm-1, which was at least twice below any other nanofiber filters. This was all attributed to the uniform capture of aerosols by electrostatic effect across the entire filter depth from the upstream to downstream layers of the multilayer electret filter. The above conclusion was confirmed by the detailed SEM images taken across the different filter layers for the multilayer filter configuration. The 4-layer electret nanofiber filter with a 3.060-gsm basis weight has 4 times more aerosol holding capacity than the single uncharged/charged nanofiber filter with the same fiber basis weight in depth filtration. Based on the standpoint of highest efficiency and capacity with maximum pressure drop 800 Pa imposed on the filtration operation, the 4-layer nanofiber electret was the best among all 4 filters. It had 52% more aerosol holding capacity than the single layer uncharged nanofiber filter and 38% more capacity than the charged single-layer and the uncharged multilayer nanofiber filters. The multilayer PVDF electret filters have excellent filtration performance for long-term aerosol filtration and also great potential applications in the fields of personal health care and environmental protection.

Electrostatic charged nanofiber filter for filtering airborne novel coronavirus (COVID-19) and nano-aerosols.

The World Health Organization declared the novel coronavirus (COVID-19) outbreak as a pandemic on March 12, 2020. Within four months since outbreak in December 2019, over 2.6 million people have been infected across 210 countries around the globe with over 180,000 deaths. COVID-19 has a size of 60-140 nm with mean size of 100 nm (i.e. nano-aerosol). The virus can be airborne by attaching to human secretion (fine particles, nasal/saliva droplets) of infected person or suspended fine particulates in air. While NIOSH has standardized N95, N99 and N100 respirators set at 300-nm aerosol, to-date there is no filter standards, nor special filter technologies, tailored for capturing airborne viruses and 100-nm nano-aerosols. The latter also are present in high number concentration in atmospheric pollutants. This study addresses developing novel charged PVDF nanofiber filter technology to effectively capture the fast-spreading, deadly airborne coronavirus, especially COVID-19, with our target aerosol size set at 100 nm (nano-aerosol), and not 300 nm. The virus and its attached aerosol were simulated by sodium chloride aerosols, 50-500 nm, generated from sub-micron aerosol generator. PVDF nanofibers, which were uniform in diameter, straight and bead-free, were produced with average fiber diameters 84, 191, 349 and 525 nm, respectively, with excellent morphology. The fibers were subsequently electrostatically charged by corona discharge. The amounts of charged fibers in a filter were increased to achieve high efficiency of 90% for the virus filter but the electrical interference between neighbouring fibers resulted in progressively marginal increase in efficiency yet much higher pressure drop across the filter. The quality factor which measured the efficiency-to-pressure-drop kept decreasing. By redistributing the fibers in the filter into several modules with lower fiber packing density, with each module separated by a permeable, electrical-insulator material, the electrical interference between neighboring charged fibers was reduced, if not fully mitigated. Also, the additional scrim materials introduced macropores into the filter together with lower fiber packing density in each module both further reduced the airflow resistance. With this approach, the quality factor can maintain relatively constant with increasing fiber amounts to achieve high filter efficiency. The optimal amounts of fiber in each module depended on the diameter of fibers in the module. Small fiber diameter that has already high performance required small amounts of fibers per module. In contrast, large diameter fiber required larger amounts of fibers per module to compensate for the poorer performance provided it did not incur significantly additional pressure drop. This approach was applied to develop four new nanofiber filters tailored for capturing 100-nm airborne COVID-19 to achieve over 90% efficiency with pressure drop not to exceed 30 Pa (3.1 mm water). One filter developed meeting the 90% efficiency has ultralow pressure drop of only 18 Pa (1.9 mm water) while another filter meeting the 30 Pa limit has high efficiency reaching 94%. These optimized filters based on rigorous engineering approach provide the badly needed technology for protecting the general public from the deadly airborne COVID-19 and other viruses, as well as nano-aerosols from air pollution which lead to undesirable chronic diseases.

Charged PVDF multilayer nanofiber filter in filtering simulated airborne novel coronavirus (COVID-19) using ambient nano-aerosols.

The novel coronavirus (COVID-19), average size 100 nm, can be aerosolized by cough, sneeze, speech and breath of infected persons. The airborne carrier for the COVID-19 can be tiny droplets and particulates from infected person, fine suspended mists (humidity) in air, or ambient aerosols in air. To-date, unfortunately there are no test standards for nano-aerosols (≤100 nm). A goal in our study is to develop air filters (e.g. respirator, facemask, ventilator, medical breathing filter/system) with 90% capture on 100-nm airborne COVID-19 with pressure drop of less than 30 Pa (3.1 mm water). There are two challenges. First, this airborne bio-nanoaerosol (combined virus and carrier) is amorphous unlike cubic NaCl crystals. Second, unlike standard laboratory tests on NaCl and test oil (DOP) droplets, these polydispersed aerosols all challenge the filter simultaneously and they are of different sizes and can interact among themselves complicating the filtration process. For the first time, we have studied these two effects using ambient aerosols (simulating the bio-nanoaerosols of coronavirus plus carrier of different shapes and sizes) to challenge electrostatically charged multilayer/multimodule nanofiber filters. This problem is fundamentally complicated due to mechanical and electrostatic interactions among aerosols of different sizes with induced charges of different magnitudes. The test filters were arranged in 2, 4, and 6 multiple-modules stack-up with each module having 0.765 g/m2 of charged PVDF nanofibers (mean diameter 525 ± 191 nm). This configuration minimized electrical interference among neighboring charged nanofibers and reduced flow resistance in the filter. For ambient aerosol size>80 nm (applicable to the smallest COVID-19), the electrostatic effect contributes 100-180% more efficiency to the existing mechanical efficiency (due to diffusion and interception) depending on the number of modules in the filter. By stacking-up modules to increase fiber basis weight in the filter, a 6-layer charged nanofiber filter achieved 88%, 88% and 96% filtration efficiency for, respectively, 55-nm, 100-nm and 300-nm ambient aerosol. This is very close to attaining our set goal of 90%-efficiency on the 100-nm ambient aerosol. The pressure drop for the 6-layer nanofiber filter was only 26 Pa (2.65 mm water column) which was below our limit of 30 Pa (3.1 mm water). For the test multi-module filters, a high 'quality factor' (efficiency-to-pressure-drop ratio) of about 0.1 to 0.13 Pa-1 can be consistently maintained, which was far better than conventional filters. Using the same PVDF 6-layer charged nanofiber filter, laboratory tests results using monodispersed NaCl aerosols of 50, 100, and 300 nm yielded filtration efficiency, respectively, 92%, 94% and 98% (qualified for 'N98 standard') with same pressure drop of 26 Pa. The 2-6% discrepancy in efficiency for the NaCl aerosols was primarily attributed to the absence of interaction among aerosols of different sizes using monodispersed NaCl aerosols in the laboratory. This discrepancy can be further reduced with increasing number of modules in the filter and for larger 300-nm aerosol. The 6-layer charged nanofiber filter was qualified as a 'N98 respirator' (98% capture efficiency for 300-nm NaCl aerosols) but with pressure drop of only 2.65-mm water which was 1/10 below conventional N95 with 25-mm (exhaling) to 35-mm (inhaling) water column! The 6-layer charged PVDF nanofiber filter provides good personal protection against airborne COVID-19 virus and nano-aerosols from pollution based on the N98 standard, yet it is at least 10X more breathable than a conventional N95 respirator.

Effect of potential HONO sources on peroxyacetyl nitrate (PAN) formation in eastern China in winter.

As an important secondary photochemical pollutant, peroxyacetyl nitrate (PAN) has been studied over decades, yet its simulations usually underestimate the corresponding observations, especially in polluted areas. Recent observations in north China found unusually high concentrations of PAN during wintertime heavy haze events, but the current model still cannot reproduce the observations, and researchers speculated that nitrous acid (HONO) played a key role in PAN formation. For the first time we systematically assessed the impact of potential HONO sources on PAN formation mechanisms in eastern China using the Weather Research and Forecasting/Chemistry (WRF-Chem) model in February of 2017. The results showed that the potential HONO sources significantly improved the PAN simulations, remarkably accelerated the ROx (sum of hydroxyl, hydroperoxyl, and organic peroxy radicals) cycles, and resulted in 80%-150% enhancements of PAN near the ground in the coastal areas of eastern China and 10%-50% enhancements in the areas around 35-40°N within 3 km during a heavy haze period. The direct precursors of PAN were aldehyde and methylglyoxal, and the primary precursors of PAN were alkenes with C > 3, xylenes, propene and toluene. The above results suggest that the potential HONO sources should be considered in regional and global chemical transport models when conducting PAN studies.

Hyphal induction under the condition without inoculation in Candida albicans is triggered by Brg1-mediated removal of NRG1 inhibition.

Candida albicans can switch between yeast and hyphae growth forms, which is critical for its pathogenesis. Diluting from saturated cells into fresh medium at 37°C is routinely used to induce hyphae, which depends on the cAMP-PKA pathway-activated transcriptional down-regulation of NRG1 and degradation of Nrg1 protein triggered by inoculation. It is reported that N-acetylglucosamine (GlcNAc), serum or neutral pH could stimulate filamentation in log phase cells, whereas how C. albicans develops hyphae without inoculation remains unknown. Here, we show that NRG1 down-regulation is necessary for hyphal growth under this condition. Instead of cAMP-PKA pathway, GlcNAc sensor Ngs1 is responsible for the down-regulation of NRG1 upon GlcNAc induction in log phase cells through its N-acetyltransferase activity. From a genetic screen, Brg1 is found to be essential for hyphal development without inoculation. Ngs1 binds to BRG1 promoter to induce its expression in GlcNAc. Importantly, constitutively expressed BRG1 induces NRG1 down-regulation even in the absence of GlcNAc or Ngs1. Serum or neutral pH-induced filamentation in log phase cells is also through Brg1-mediated NRG1 down-regulation. Our study provides a molecular mechanism for how C. albicans forms hyphae in different cell states. This flexibility may facilitate C. albicans to adapt varied host environment during infection.

Satellite-Based Detection and Characterization of Industrial Heat Sources in China.

Despite their important contribution to the economic domain, active heat-releasing industrial plants have significant implications for human health and climate change. However, a spatially detailed dataset of various heat-releasing industrial sectors and large-scale characterization of heat emissions from industrial sources have not been reported yet. In this study, a dataset of heat-releasing industries was established using a national detection map of thermal anomalies produced by a novel and more accurate method employing daily nighttime visible infrared imaging radiometer suite thermal infrared images corresponding to 1 year. Subsequently, we quantified the dimensional features of heat radiation fluxes of China's industrial plants. A total of 12 114 industrial objects were structured in a two-level hierarchical dataset of heat-releasing industries, representing a magnitude of at least 1 order higher than the number enumerated in the state-of-the-art inventory of industrial heat sources across China. The satellite observations helped more completely characterize industrial heat plumes, which represent the industrial heat radiation fluxes with higher levels of densities that prevail in the central-eastern part of China having spatial clustering islands. Our results could be used to inform policy and environmental management in relation to meaningful dynamic industrial supervision, targeting extreme polluters and differentiated emission mitigation measurements.

Synergistic Nanotubular Copper-Doped Nickel Catalysts for Hydrogen Evolution Reactions.

Developing highly active electrocatalysts with low cost and high efficiency for hydrogen evolution reactions (HERs) is of great significance for industrial water electrolysis. Herein, a 3D hierarchically structured nanotubular copper-doped nickel catalyst on nickel foam (NF) for HER is reported, denoted as Ni(Cu), via facile electrodeposition and selective electrochemical dealloying. The as-prepared Ni(Cu)/NF electrode holds superlarge electrochemical active surface area and exhibits Pt-like electrocatalytic activity for HER, displaying an overpotential of merely 27 mV to achieve a current density of 10 mA cm-2 and an extremely small Tafel slope of 33.3 mV dec-1 in 1 m KOH solution. The Ni(Cu)/NF electrode also shows excellent durability and robustness in both continuous and intermittent bulk water electrolysis. Density functional theory calculations suggest that Cu substitution and the formation of NiO on the surface leads to more optimal free energy for hydrogen adsorption. The lattice distortion of Ni caused by Cu substitution, the increased interfacial activity induced by surface oxidation of nanoporous Ni, and numerous active sites at Ni atom offered by the 3D hierarchical porous structure, all contribute to the dramatically enhanced catalytic performance. Benefiting from the facile, scalable preparation method, this highly efficient and robust Ni(Cu)/NF electrocatalyst holds great promise for industrial water-alkali electrolysis.

Analysis of cobalt phosphide (CoP) nanorods designed for non-enzyme glucose detection.

The nanorods of cobalt phosphide have been prepared and evaluated as an electrocatalyst for non-enzyme glucose detection. The nanorods were used to modify the surface of an electrode and detect glucose without the help of an enzyme for the first time. The crystal structure and composition of cobalt phosphide were identified by XRD and XPS, respectively, and the morphology of the as-prepared samples was observed by FESEM and TEM. The electrochemical measurement results indicate that the CoP-based sensor exhibits excellent catalytic activity and a far lower detection potential compared to bare GCE. Specifically, the electrocatalytic mechanism of CoP in the detection of glucose was proposed based on a series of physical characterization methods, electrochemical measurements, and theoretical calculations.

Nanostring-cluster hierarchical structured Bi2O3: synthesis, evolution and application in biosensing.

In the present study, a simple strategy was developed to fabricate a new Bi2O3 nanostring-cluster hierarchical structure. Precursor microrods composed of Bi(C2O4)OH were initially grown under hydrothermal conditions. After calcination in air, Bi(C2O4)OH microrods were carved into unique string-cluster structures by the gas produced during the decomposition process. To explain the formation mechanism, the effects of pyrolysis temperature and time on the morphology of the as-prepared samples were investigated and are discussed in detail. It was discovered that the nanostring-cluster-structured Bi2O3 consists of thin nanoplatelet arrays, which is advantageous for glucose enzyme immobilization and for designing biosensors. The resulting Bi2O3 structure showed an excellent capability in the modification of electrode surfaces in biosensors by enhancing the sensitivity, with good specificity and response time. Such qualities of a biosensor are ideal characteristics for glucose sensing performance and allow for further explorations of its application in other fields.

pH-controllable synthesis of unique nanostructured tungsten oxide aerogel and its sensitive glucose biosensor.

This work presents a controllable synthesis of nanowire-networked tungsten oxide aerogels, which was performed by varying the pH in a polyethyleneimine (PEI)-assisted hydrothermal process. An enzyme-tungsten oxide aerogel co-modified electrode shows high activity and selectivity toward glucose oxidation, thus holding great promise for applications in bioelectronics.

Charged Fibrous Dressing to Promote Diabetic Chronic Wound Healing.

Diabetic chronic wounds cause a significant amount of pain to patients because of their low cure rates and high recurrence rates. Traditional approaches to treating diabetic chronic wounds often involve the delivery of drugs or cytokines that regulate the microenvironment and eliminate bacterial infection in the wound area, but they are passive in controlling cell behaviors and may lead to drug resistance. Emerging drug-free wound treatments are important for convenient, effective, and safe treatment strategies. However, the current approaches cannot fully promote tissue regeneration or prevent bacterial infections. Here, the efficacy of a negatively charged fiber dressing in promoting diabetic chronic wound healing is investigated. The negatively charged fiber dressing can generate reactive oxygen species to inhibit bacterial reproduction with the assistance of ultrasound during the inflammatory phase. Furthermore, the dressing provides an electrostatic field that regulates cellular behavior during the inflammatory and proliferative phases. In particular, the dressing can promote fibroblast migration and induce macrophage polarization and neovascularization without any additional drugs. It is demonstrated that this strategy enables the healing of diabetic chronic wounds in a mouse model, achieving effective wound closure over a 12-day treatment cycle and providing a drug-free therapeutic strategy for diabetic chronic wound care.