bluuebunny/crossref_metadata_2025 huggingface dataset:
Climatic niche evolution in the viviparous Sceloporus torquatus group (Squamata: Phrynosomatidae).
Authors: Martínez-Méndez Norberto , Mejía Omar , Ortega Jorge , Méndez-de la Cruz Fausto R.
Published: December 2017

The cold-climate hypothesis is the main and most supported explanation of the evolution of viviparity among reptiles. This hypothesis sustains that viviparity arose as a means to save eggs from an increased mortality in nests linked with low temperatures. In this sense, some authors have stated that viviparity could constitute an evolutionary constraint. However, the link between evolutionary constraints and the evolution of ecological niches has not been well studied. Here, we study the climatic niche evolution of a group of viviparous lizards from North America to test whether the diversification of the group is linked with Phylogenetic Niche Conservatism (PNC). We evaluated phylogenetic signals and trait evolution, besides a reconstruction of ancestral climate tolerances, and did not find PNC in the ecological niche of the species in the group. Surprisingly, we did not find conservatism in any bioclimatic variables associated with temperature; we only had evidence of conservatism in Precipitation Seasonality (Bio15) and Precipitation of Coldest Quarter (Bio19). Analysis of relative disparity through time (DTT) indicates high divergence around 4.0 MYA and 0.65 MYA that coincides with orogenic and glacial periods. There is no evidence that climatic niche differentiation was the main factor in the diversification of the studied group. Orogenic and glacial periods probably promote cycles of the availability of new territories and isolation, which could promote the rapid accumulation of ecological differences between the species of the group.
Phenotype inference in an Escherichia coli strain panel
Authors: Galardini Marco , Koumoutsi Alexandra , Herrera-Dominguez Lucia , Cordero Varela Juan Antonio , Telzerow Anja , Wagih Omar , Wartel Morgane , Clermont Olivier , Denamur Erick , Typas Athanasios , Beltrao Pedro
Published: December 2017

Understanding how genetic variation contributes to phenotypic differences is a fundamental question in biology. Combining high-throughput gene function assays with mechanistic models of the impact of genetic variants is a promising alternative to genome-wide association studies. Here we have assembled a large panel of 696 Escherichia coli strains, which we have genotyped and measured their phenotypic profile across 214 growth conditions. We integrated variant effect predictors to derive gene-level probabilities of loss of function for every gene across all strains. Finally, we combined these probabilities with information on conditional gene essentiality in the reference K-12 strain to compute the growth defects of each strain. Not only could we reliably predict these defects in up to 38% of tested conditions, but we could also directly identify the causal variants that were validated through complementation assays. Our work demonstrates the power of forward predictive models and the possibility of precision genetic interventions.
Transcription-factor-dependent enhancer transcription defines a gene regulatory network for cardiac rhythm
Authors: Yang Xinan H , Nadadur Rangarajan D , Hilvering Catharina RE , Bianchi Valerio , Werner Michael , Mazurek Stefan R , Gadek Margaret , Shen Kaitlyn M , Goldman Joseph Aaron , Tyan Leonid , Bekeny Jenna , Hall Johnathon M , Lee Nutishia , Perez-Cervantes Carlos , Burnicka-Turek Ozanna , Poss Kenneth D , Weber Christopher R , de Laat Wouter , Ruthenburg Alexander J , Moskowitz Ivan P
Published: December 2017

The noncoding genome is pervasively transcribed. Noncoding RNAs (ncRNAs) generated from enhancers have been proposed as a general facet of enhancer function and some have been shown to be required for enhancer activity. Here we examine the transcription-factor-(TF)-dependence of ncRNA expression to define enhancers and enhancer-associated ncRNAs that are involved in a TF-dependent regulatory network. TBX5, a cardiac TF, regulates a network of cardiac channel genes to maintain cardiac rhythm. We deep sequenced wildtype and Tbx5-mutant mouse atria, identifying ~2600 novel Tbx5-dependent ncRNAs. Tbx5-dependent ncRNAs were enriched for tissue-specific marks of active enhancers genome-wide. Tbx5-dependent ncRNAs emanated from regions that are enriched for TBX5-binding and that demonstrated Tbx5-dependent enhancer activity. Tbx5-dependent ncRNA transcription provided a quantitative metric of Tbx5-dependent enhancer activity, correlating with target gene expression. We identified RACER, a novel Tbx5-dependent long noncoding RNA (lncRNA) required for the expression of the calcium-handling gene Ryr2. We illustrate that TF-dependent enhancer transcription can illuminate components of TF-dependent gene regulatory networks.
The kinetics of pre-mRNA splicing in the Drosophila genome and the influence of gene architecture
Authors: Pai Athma A , Henriques Telmo , McCue Kayla , Burkholder Adam , Adelman Karen , Burge Christopher B
Published: December 2017

Production of most eukaryotic mRNAs requires splicing of introns from pre-mRNA. The splicing reaction requires definition of splice sites, which are initially recognized in either intron-spanning (‘intron definition’) or exon-spanning (‘exon definition’) pairs. To understand how exon and intron length and splice site recognition mode impact splicing, we measured splicing rates genome-wide in Drosophila, using metabolic labeling/RNA sequencing and new mathematical models to estimate rates. We found that the modal intron length range of 60–70 nt represents a local maximum of splicing rates, but that much longer exon-defined introns are spliced even faster and more accurately. We observed unexpectedly low variation in splicing rates across introns in the same gene, suggesting the presence of gene-level influences, and we identified multiple gene level variables associated with splicing rate. Together our data suggest that developmental and stress response genes may have preferentially evolved exon definition in order to enhance the rate or accuracy of splicing.
Interactions between stimulus and response types are more strongly represented in the entorhinal cortex than in its upstream regions in rats
Authors: Park Eun-Hye , Ahn Jae-Rong , Lee Inah
Published: December 2017

Previously we reported results which suggested that response types are critical in dissociating the lateral entorhinal cortex (LEC) from the medial entorhinal cortex (MEC) in a scene memory task (Yoo and Lee, 2017). Here, we investigated whether the perirhinal cortex (PER) and postrhinal cortex (POR), the upstream regions of the LEC and MEC, respectively, could be dissociated similarly. We conducted four tasks by combining different stimulus and response types. Our results suggest that the PER is important whenever object recognition is required and, together with prior findings, imply that PER-LEC networks are essential in goal-directed interactions with objects. The POR appears critical for recognizing visual scenes and may play key roles in scene-based navigation together with the MEC. The relative lack of functional dissociation between stimulus and response types at the PER-POR level suggests that actions conditioned on the recognition of external stimuli may be uniquely represented from the EC.
Decoding the centromeric nucleosome through CENP-N
Authors: Pentakota Satyakrishna , Zhou Keda , Smith Charlotte , Maffini Stefano , Petrovic Arsen , Morgan Garry P , Weir John R , Vetter Ingrid R , Musacchio Andrea , Luger Karolin
Published: December 2017

Centromere protein (CENP) A, a histone H3 variant, is a key epigenetic determinant of chromosome domains known as centromeres. Centromeres nucleate kinetochores, multi-subunit complexes that capture spindle microtubules to promote chromosome segregation during mitosis. Two kinetochore proteins, CENP-C and CENP-N, recognize CENP-A in the context of a rare CENP-A nucleosome. Here, we reveal the structural basis for the exquisite selectivity of CENP-N for centromeres. CENP-N uses charge and space complementarity to decode the L1 loop that is unique to CENP-A. It also engages in extensive interactions with a 15-base pair segment of the distorted nucleosomal DNA double helix, in a position predicted to exclude chromatin remodelling enzymes. Besides CENP-A, stable centromere recruitment of CENP-N requires a coincident interaction with a newly identified binding motif on nucleosome-bound CENP-C. Collectively, our studies clarify how CENP-N and CENP-C decode and stabilize the non-canonical CENP-A nucleosome to enforce epigenetic centromere specification and kinetochore assembly.
Mitochondrial DNA damage and reactive oxygen species in neurodegenerative disease
Authors: Nissanka Nadee , Moraes Carlos T.
Published: December 2017

Mitochondria are essential organelles within the cell where most ATP is produced through oxidative phosphorylation (OXPHOS). A subset of the genes needed for this process are encoded by the mitochondrial DNA (mtDNA). One consequence of OXPHOS is the production of mitochondrial reactive oxygen species (ROS), whose role in mediating cellular damage, particularly in damaging mtDNA during ageing, has been controversial. There are subsets of neurons that appear to be more sensitive to ROS‐induced damage, and mitochondrial dysfunction has been associated with several neurodegenerative disorders. In this review, we will discuss the current knowledge in the field of mtDNA and neurodegeneration, the debate about ROS as a pathological or beneficial contributor to neuronal function, bona fide mtDNA diseases, and insights from mouse models of mtDNA defects affecting the central nervous system.
Geochemical and Crystallographic Study ofTurbo Torquatus(Mollusca: Gastropoda) From Southwestern Australia
Authors: Roger L. M. , George A. D. , Shaw J. , Hart R. D. , Roberts M. P. , Becker T. , Evans N. J. , McDonald B. J.
Published: December 2017

Shells of the marine gastropodTurbo torquatuswere sampled from three different locations along the Western Australian coastline, namely Marmion Lagoon (31°S), Rottnest Island (32°S), and Hamelin Bay (34°S). Marmion Lagoon and Rottnest Island have similar sea surface temperature ranges that are ∼1°C warmer than Hamelin Bay, with all sites influenced by the warm southward flowing Leeuwin Current. The shells were characterized using crystallographic, spectroscopic, and geochemical analyses. Shell mineral composition varies between the three sites suggesting the influence of sea surface temperature, oxygen consumption, and/or bedrock composition on shell mineralogy and preferential incorporation and/or elemental discrimination of Mg, P, and S. Furthermore,T. torquatuswas found to exert control over the incorporation of most, if not all, the elements measured here, suggesting strong biological regulation. At all levels of testing, the concentrations of Li varied significantly, which indicates that this trace element may not be a suitable environmental proxy. Variation in Sr concentration between sites and between specimens reflects combined environmental and biological controls suggesting that Sr/Ca ratios inT. torquatuscannot be used to estimate sea surface temperature without experimentally accounting for metabolic and growth effects. The mineral composition and microstructure ofT. torquatusshells may help identify sea surface temperature variations on geological time scales. These findings support the previously hypothesized involvement of an active selective pathway across the calcifying mantle ofT. torquatusfor most, if not all, the elements measured here.
Estimating Bulk Entrainment With Unaggregated and Aggregated Convection
Authors: Becker Tobias , Bretherton Christopher S. , Hohenegger Cathy , Stevens Bjorn
Published: December 2017

To investigate how entrainment is influenced by convective organization, we use the ICON (ICOsahedral Nonhydrostatic) model in a radiative‐convective equilibrium framework, with a 1 km spatial grid mesh covering a 600 by 520 km2 domain. We analyze two simulations, with unaggregated and aggregated convection, and find that, in the lower free troposphere, the bulk entrainment rate increases when convection aggregates. The increase of entrainment rate with aggregation is caused by a strong increase of turbulence in the close environment of updrafts, masking other effects like the increase of updraft size and of static stability with aggregation. Even though entrainment rate increases with aggregation, updraft buoyancy reduction through entrainment decreases because aggregated updrafts are protected by a moist shell. Parameterizations that wish to represent mesoscale convective organization would need to model this moist shell.
Optical Modeling of Sea Salt Aerosols: The Effects of Nonsphericity and Inhomogeneity
Authors: Bi Lei , Lin Wushao , Wang Zheng , Tang Xiaoyun , Zhang Xiaoyu , Yi Bingqi
Published: December 2017

The nonsphericity and inhomogeneity of marine aerosols (sea salts) have not been addressed in pertinent radiative transfer calculations and remote sensing studies. This study investigates the optical properties of nonspherical and inhomogeneous sea salts using invariant imbedding T‐matrix simulations. Dry sea salt aerosols are modeled based on superellipsoidal geometries with a prescribed aspect ratio and roundness parameter. Wet sea salt particles are modeled as coated superellipsoids, as spherical particles with a superellipsoidal core, and as homogeneous spheres depending on the level of relative humidity. Aspect ratio and roundness parameters are found to be critical to interpreting the linear depolarization ratios (LDRs) of NaCl crystals from laboratory measurements. The optimal morphology parameters of NaCl necessary to reproduce the measurements are found to be consistent with data gleaned from an electron micrograph. The LDRs of wet sea salts are computed based on inhomogeneous models and compared with the measured data from ground‐based LiDAR. The dependence of the LDR on relative humidity is explicitly considered. The increase in the LDR with relative humidity at the initial phase of deliquescence is attributed to both the size increase and the inhomogeneity effect. For large humidity values, the LDR substantially decreases because the overall particle shape becomes more spherical and the inhomogeneity effect in a particle on the LDR is suppressed for submicron sea salts. However, the effect of inhomogeneity on optical properties is pronounced for coarse‐mode sea salts. These findings have important implications for atmospheric radiative transfer and remote sensing involving sea salt aerosols.
Interannual Variability of Regional Hadley Circulation Intensity Over Western Pacific During Boreal Winter and Its Climatic Impact Over Asia‐Australia Region
Authors: Huang Ruping , Chen Shangfeng , Chen Wen , Hu Peng
Published: December 2017

This study investigates interannual variability of boreal winter regional Hadley circulation over western Pacific (WPHC) and its climatic impacts. A WPHC intensity index (WPHCI) is defined as the vertical shear of the divergent meridional winds. It shows that WPHCI correlates well with the El Niño–Southern Oscillation (ENSO). To investigate roles of the ENSO‐unrelated part of WPHCI (WPHCIres), variables that are linearly related to the Niño‐3 index have been removed. It reveals that meridional sea surface temperature gradient over the western Pacific plays an essential role in modulating the WPHCIres. The climatic impacts of WPHCIres are further investigated. Below‐normal (above‐normal) precipitation appears over south China (North Australia) when WPHCIres is stronger. This is due to the marked convergence (divergence) anomalies at the upper troposphere, divergence (convergence) at the lower troposphere, and the accompanied downward (upward) motion over south China (North Australia), which suppresses (enhances) precipitation there. In addition, a pronounced increase in surface air temperature (SAT) appears over south and central China when WPHCIres is stronger. A temperature diagnostic analysis suggests that the increase in SAT tendency over central China is primarily due to the warm zonal temperature advection and subsidence‐induced adiabatic heating. In addition, the increase in SAT tendency over south China is primarily contributed by the warm meridional temperature advection. Further analysis shows that the correlation of WPHCIres with the East Asian winter monsoon (EAWM) is weak. Thus, this study may provide additional sources besides EAWM and ENSO to improve understanding of the Asia‐Australia climate variability.
Effects of a Simple Convective Organization Scheme in a Two‐Plume GCM
Authors: Chen Baohua , Mapes Brian E.
Published: December 2017

A set of experiments is described with the Community Atmosphere Model (CAM5) using a two‐plume convection scheme. To represent the differences of organized convection from General Circulation Model (GCM) assumptions of isolated plumes in uniform environments, a dimensionless prognostic “organization” tracer Ω is invoked to lend the second plume a buoyancy advantage relative to the first, as described in Mapes and Neale (2016). When low‐entrainment plumes are unconditionally available (Ω = 1 everywhere), deep convection occurs too easily, with consequences including premature (upstream) rainfall in inflows to the deep tropics, excessive convective versus large‐scale rainfall, poor relationships to the vapor field, stable bias in the mean state, weak and poor tropical variability, and midday peak in diurnal rainfall over land. Some of these are shown to also be characteristic of CAM4 with its separated deep and shallow convection schemes. When low‐entrainment plumes are forbidden by setting Ω = 0 everywhere, some opposite problems can be discerned. In between those extreme cases, an interactive Ω driven by the evaporation of precipitation acts as a local positive feedback loop, concentrating deep convection: In areas of little recent rain, only highly entraining plumes can occur, unfavorable for rain production. This tunable mechanism steadily increases precipitation variance in both space and time, as illustrated here with maps, time‐longitude series, and spectra, while avoiding some mean state biases as illustrated with process‐oriented diagnostics such as conserved variable profiles and vapor‐binned precipitation curves.
Effect of desipramine on patients with breathing disorders in RETT syndrome
Authors: Mancini Josette , Dubus Jean‐Christophe , Jouve Elisabeth , Roux Jean‐Christophe , Franco Patricia , Lagrue Emmanuelle , Castelnau Pierre , Cances Claude , Chaix Yves , Rougeot‐Jung Christelle , Cornu Catherine , Desportes Vincent , Vallée Louis , Bahi‐Buisson Nadia , Truillet Romain , Attolini Laurence , Villard Laurent , Blin Olivier , Micallef Joëlle
Published: December 2017

Objective

Rett Syndrome (RTT) is a severe neurodevelopmental condition with breathing disorders, affecting around one in 10,000 female births. Desipramine, a noradrenaline reuptake inhibitor, reduced the number of apneas in Mecp2‐deficient mice, a model of RTT. We planned a phase 2 trial to test its efficacy and its safety on breathing patterns in 36 girls with RTT.

Methods

The trial was a 6‐month, multicenter, randomized, double‐blind, placebo‐controlled study registered with ClinicalTrials.gov, number NCT00990691. Girls diagnosed according to clinical examination and confirmed by genotyping were randomly assigned in a 1:1:1 ratio to receive 2–3 mg/kg Desipramine per day (high Desipramine), 1–2 mg/kg Desipramine per day (low Desipramine), or a placebo. The primary outcome was the change of apnea hypopnea index (AHI), defined by the number of apnea and hypopnea events per hour, assessed at 6 months from baseline. Intention‐to‐treat analysis was applied.

Results

The median change in AHI from baseline to 6 months was −31 (IQR: −37 to −11) for the high Desipramine, −17.5 (IQR: −31 to 13) for the low Desipramine, and −13 (IQR:−31 to 0) for the placebo group. We did not find any significant difference in these changes between the groups (P = 0.781). A significant inverse correlation between Desipramine plasma concentration and AHI (r = −0.44; P = 0.0002) was underlined.

Interpretation

This first clinical trial of desipramine did not show clinical efficacy. Although required further studies, the significant correlation between Desipramine concentrations and improvement of AHI provided additional and relevant reasons to test the noradrenergic pathway in RTT.
Novel Antibacterial and Bioactive Silicate Glass Nanoparticles for Biomedical Applications
Authors: Vale Ana Catarina , Carvalho Ana Luísa , Barbosa Ana Margarida , Torrado Egídio , Mano João F. , Alves Natália M.
Published: December 2017

In this work, the authors propose a new quick sol–gel procedure for bioglass nanoparticles production containing 10% mol of silver (AgBGs). These new AgBGs are characterized by Zeta potential analysis, scanning electron microscopy with X‐ray microanalysis (SEM/EDS), X‐ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and microbiological tests to confirm their bioactive and antibacterial properties. SEM shows that the average particle size is less than 200 nm and EDS confirms the successful incorporation of Ag2O in the bioglass matrix. XRD confirms the amorphous nature of the AgBGs and, after SBF immersion, reveals their bioactive behavior with the presence of crystalline phase of calcium silicate and phosphorus oxide, which are also detected by FTIR analysis. FTIR also confirms the formation of typical siloxane bonds resulting from the condensation of silicate glass. Lastly, it is found that the developed AgBGs has an antibacterial effect against two different types of bacteria, thus demonstrating their ability to reduce the bacterial infection within 16 h.
Advances in Magnetic Nanoparticles for Biomedical Applications
Authors: Cardoso Vanessa Fernandes , Francesko António , Ribeiro Clarisse , Bañobre‐López Manuel , Martins Pedro , Lanceros‐Mendez Senentxu
Published: December 2017

Magnetic nanoparticles (NPs) are emerging as an important class of biomedical functional nanomaterials in areas such as hyperthermia, drug release, tissue engineering, theranostic, and lab‐on‐a‐chip, due to their exclusive chemical and physical properties. Although some works can be found reviewing the main application of magnetic NPs in the area of biomedical engineering, recent and intense progress on magnetic nanoparticle research, from synthesis to surface functionalization strategies, demands for a work that includes, summarizes, and debates current directions and ongoing advancements in this research field. Thus, the present work addresses the structure, synthesis, properties, and the incorporation of magnetic NPs in nanocomposites, highlighting the most relevant effects of the synthesis on the magnetic and structural properties of the magnetic NPs and how these effects limit their utilization in the biomedical area. Furthermore, this review next focuses on the application of magnetic NPs on the biomedical field. Finally, a discussion of the main challenges and an outlook of the future developments in the use of magnetic NPs for advanced biomedical applications are critically provided.
Moldable Hyaluronan Hydrogel Enabled by Dynamic Metal–Bisphosphonate Coordination Chemistry for Wound Healing
Authors: Shi Liyang , Zhao Yannan , Xie Qifan , Fan Caixia , Hilborn Jöns , Dai Jianwu , Ossipov Dmitri. A.
Published: December 2017

Biomaterial‐based regenerative approaches would allow for cost‐effective off‐the‐shelf solution for the treatment of wounds. Hyaluronan (HA)‐based hydrogel is one attractive biomaterial candidate because it is involved in natural healing processes, including inflammation, granulation, and reepithelialization. Herein, dynamic metal–ligand coordination bonds are used to fabricate moldable supramolecular HA hydrogels with self‐healing properties. To achieve reversible crosslinking of HA chains, the biopolymer is modified with pendant bisphosphonate (BP) ligands using carbodiimide coupling and chemoselective “click” reactions. Hydrogel is formed immediately after simple addition of silver (Ag+) ions to the solution of HA containing BP groups (HA‐BP). Compared with previous HA‐based wound healing hydrogels, the HA‐BP·Ag+ hydrogel is highly suitable for clinical use as it can fill irregularly shaped wound defects without the need for premolding. The HA‐BP·Ag+ hydrogel shows antimicrobial properties to both Gram‐positive and Gram‐negative bacterial strains, enabling prevention of infections in wound care. In vivo evaluation using a rat full‐thickness skin wound model shows significantly lower wound remaining rate and a thicker layer of regenerated epidermis as compared with the group left without treatment. The presented moldable and self‐healing supramolecular HA hydrogel with “ready‐to‐use” properties possesses a great potential for regenerative wound treatment.
Fluorination Enhances Serum Stability of Bioreducible Poly(amido amine) Polyplexes and Enables Efficient Intravenous siRNA Delivery
Authors: Chen Gang , Wang Kaikai , Wang Yixin , Wu Pengkai , Sun Minjie , Oupický David
Published: December 2017

The use of small interfering RNA (siRNA) in cancer treatment has been limited by the lack of effective systemic delivery methods. Although synthetic polycations have been widely explored in siRNA delivery, polycation/siRNA polyplexes often suffer from insufficient stability in vivo. Here, rationally designed siRNA delivery systems that meet the requirements for systemic siRNA delivery to distant tumors are reported. The hypothesis that modular design of delivery systems based on poly(amido amine)s that combine fluorination for systemic stability with bioreducibility for easy intracellular siRNA release, and PEGylation for improved safety and colloidal stability will overcome problems with contradicting siRNA delivery demands is tested. PEGylated, fluorinated, and bioreducible copolymers (PEG‐PCD‐F) with different degree of fluorination are thus synthesized. The fluorinated copolymers readily formed polyplexes with siRNA and achieved greatly improved gene silencing efficacy in multiple cell lines in vitro when compared with nonfluorinated controls. The results show fluorination‐induced enhancement of stability, cellular uptake, and endosomal escape of the polyplexes, while exhibiting efficient siRNA release in reducing intracellular environment. PEG‐PCD‐F polyplexes with siRNA against Bcl2 inhibit breast tumor growth following systemic intravenous administration. The results provide strong evidence of successful combination of bioreducibility with fluorination and PEGylation to achieve systemic siRNA polyplex delivery.
A Fluorescent Biofunctional DNA Hydrogel Prepared by Enzymatic Polymerization
Authors: Geng Jinhui , Yao Chi , Kou Xiaohong , Tang Jianpu , Luo Dan , Yang Dayong
Published: December 2017

DNA has arisen as a promising building material for the construction of hydrogels owing to its unique properties such as designability and biocompatibility. All‐DNA hydrogels with only DNA molecules may have limited applications; hence a composite DNA hydrogel with multifunctional moieties is highly desired to cater for specific applications. Herein, a multifunctional DNA hydrogel is created by incorporating DNA with silver nanoclusters (AgNCs), in which AgNCs render the hydrogel simultaneously with fluorescent and antibacterial functions. A circular DNA is rationally designed, which allows for the elongation of DNA chain via an enzymatic polymerization as well as the formation of AgNCs onto DNA scaffolds. The resultant hybrid DNA hydrogel not only shows distinctive morphology and mechanical properties, but also exhibits fluorescent and antibacterial functions. These characteristics, along with its biocompatibility, will allow the hydrogel to be suitable for a variety of potential biomedical applications such as tissue engineering, wound dressing, biosensing, and bioimaging.
Current Approaches to Bone Tissue Engineering: The Interface between Biology and Engineering
Authors: Li Jiao Jiao , Ebied Mohamed , Xu Jen , Zreiqat Hala
Published: December 2017

The successful regeneration of bone tissue to replace areas of bone loss in large defects or at load‐bearing sites remains a significant clinical challenge. Over the past few decades, major progress is achieved in the field of bone tissue engineering to provide alternative therapies, particularly through approaches that are at the interface of biology and engineering. To satisfy the diverse regenerative requirements of bone tissue, the field moves toward highly integrated approaches incorporating the knowledge and techniques from multiple disciplines, and typically involves the use of biomaterials as an essential element for supporting or inducing bone regeneration. This review summarizes the types of approaches currently used in bone tissue engineering, beginning with those primarily based on biology or engineering, and moving into integrated approaches in the areas of biomaterial developments, biomimetic design, and scalable methods for treating large or load‐bearing bone defects, while highlighting potential areas for collaboration and providing an outlook on future developments.
Selective Cell Penetrating Peptide‐Functionalized Polymersomes Mediate Efficient and Targeted Delivery of Methotrexate Disodium to Human Lung Cancer In Vivo
Authors: Yang Weijing , Xia Yifeng , Fang Yuan , Meng Fenghua , Zhang Jian , Cheng Ru , Deng Chao , Zhong Zhiyuan
Published: December 2017

It is a long challenge to develop nanomedicines that simultaneously possess tumor cell selectivity and penetration functions. Here, it is reported that selective cell penetrating peptide (RLWMRWYSPRTRAYGC)‐functionalized polymersomes (SCPP‐PS) mediate efficient and targeted delivery of methotrexate disodium (MTX) to human lung cancer in vivo. SCPP‐PS with an SCPP density of 18.7% is self‐crosslinked, has a small size (63–65 nm), and high MTX loading (up to 19.4 wt%), shows selective uptake and fast penetration into A549 lung cancer cells, and efficiently releases MTX intracellularly. Interestingly, MTX‐loaded SCPP‐PS (MTX‐SCPP‐PS) displays much lower IC50 than those of MTX‐PS and free MTX. Installing SCPP to polymersomes has no detrimental effect to their long blood circulation time but significantly increases drug accumulation in A549 tumor (5.3% injected dose per gram at 8 h post injection). Remarkably, SCPP‐PS exhibits deep penetration in to A549 tumors. MTX‐SCPP‐PS completely inhibits tumor progression and significantly improves survival rates in mice bearing A549 lung tumor xenografts as compared to MTX‐PS and free MTX groups (median survival time: 75 vs 45 and 38 d, respectively), without causing noticeable adverse effects. These results highlight that functionalization of nanomedicines with SCPP is a feasible strategy to achieve efficient and targeted tumor therapy.
Thermoresponsive Supramolecular Chemotherapy by “V”‐Shaped Armed β‐Cyclodextrin Star Polymer to Overcome Drug Resistance
Authors: Fan Xiaoshan , Cheng Hongwei , Wang Xiaoyuan , Ye Enyi , Loh Xian Jun , Wu Yun‐Long , Li Zibiao
Published: December 2017

Pump mediated drug efflux is the key reason to result in the failure of chemotherapy. Herein, a novel star polymer β‐CD‐v‐(PEG‐β‐PNIPAAm)7 consisting of a β‐CD core, grafted with thermo‐responsive poly(N‐isopropylacrylamide) (PNIPAAm) and biocompatible poly(ethylene glycol) (PEG) in the multiple “V”‐shaped arms is designed and further fabricated into supramolecular nanocarriers for drug resistant cancer therapy. The star polymer could encapsulate chemotherapeutics between β‐cyclodextrin and anti‐cancer drug via inclusion complex (IC). Furthermore, the temperature induced chain association of PNIPAAm segments facilitated the IC to form supramolecular nanoparticles at 37 °C, whereas the presence of PEG impart great stability to the self‐assemblies. When incubated with MDR‐1 membrane pump regulated drug resistant tumor cells, much higher and faster cellular uptake of the supramolecular nanoparticles were detected, and the enhanced intracellular retention of drugs could lead to significant inhibition of cell growth. Further in vivo evaluation showed high therapeutic efficacy in suppressing drug resistant tumor growth without a significant impact on the normal functions of main organs. This work signifies thermo‐responsive supramolecular chemotherapy is promising in combating pump mediated drug resistance in both in vitro and in vivo models, which may be encouraging for the advanced drug delivery platform design to overcome drug resistant cancer.
Utilization of Peroxide Reduction Reaction at Air–Liquid–Solid Joint Interfaces for Reliable Sensing System Construction
Authors: Song Zhiqian , Xu Chenlong , Sheng Xia , Feng Xinjian , Jiang Lei
Published: December 2017

The utilization of hydrogen peroxide (H2O2) cathodic reaction is an ideal approach to develop reliable biosensors that are immune to interferences arising from oxidizable endogenous/exogenous species in biological solutions. However, practical application of such a detection scheme is limited due to the significantly fluctuating oxygen levels in solutions, as oxygen can be reduced at similar potentials. Herein, this limitation is addressed by developing a novel electrode system with superhydrophobicity‐mediated air–liquid–solid joint interfaces, which allows the rapid and continuous transport of oxygen from the air phase to the electrode surface and provides a fixed interfacial oxygen concentration. Using cathodic measurement of the enzymatic product H2O2, the sensing platform is applied to detect glucose, a model analyte, achieving a remarkably high selectivity (≈2% signal modulation due to common biologic interferents), sensitivity (18.56 µA cm−2 mm−1), and a dynamic linear range up to 80 × 10−3m. The utility of H2O2 reduction reaction at triphase interface to achieve reliable sensing platforms is general, and hence has broad potential in the fields of medical research, clinical diagnosis, and environmental analysis.
Combined Effect of the Microstructure and Underlying Surface Curvature on the Performance of Biomimetic Adhesives
Authors: Kizilkan Emre , Gorb Stanislav N.
Published: December 2017

The importance of the geometry of the micro‐/nanosized attachment elements for adhesive characteristics of gecko‐inspired microstructured surfaces has been comprehensively discussed in recent years. Due to the complex hierarchical structure of these systems, they possess a broad range of adhesion control capabilities by either passive or active adaptability of their underlying structures to the specific substrate and/or behavioral situation. Here, the influence of macroscopic geometry of backing layers hosting biomimetic microstructured surfaces is examined. The flat, convex, and concave macroscopic configurations of the bioinspired microstructured adhesive surfaces are examined on their adhesive performance under varying degrees of curvature and preloads. Microstructured surfaces demonstrated an adhesion range differing by up to a factor of 2 alone through varying backing layer configuration. The results can aid in understanding the influence of curvature geometry on hierarchically structured adhesive systems and the implementation of biomimetic structured surfaces in applications such as robots and grippers optimized for different sized objects.
3D‐Printed Biomimetic Super‐Hydrophobic Structure for Microdroplet Manipulation and Oil/Water Separation
Authors: Yang Yang , Li Xiangjia , Zheng Xuan , Chen Zeyu , Zhou Qifa , Chen Yong
Published: December 2017

Biomimetic functional surfaces are attracting increasing attention for various technological applications, especially the superhydrophobic surfaces inspired by plant leaves. However, the replication of the complex hierarchical microstructures is limited by the traditional fabrication techniques. In this paper, superhydrophobic micro‐scale artificial hairs with eggbeater heads inspired by Salvinia molesta leaf was fabricated by the Immersed surface accumulation three dimensional (3D) printing process. Multi‐walled carbon nanotubes were added to the photocurable resins to enhance the surface roughness and mechanical strength of the microstructures. The 3D printed eggbeater surface reveals interesting properties in terms of superhydrophobilicity and petal effect. The results show that a hydrophilic material can macroscopically behave as hydrophobic if a surface has proper microstructured features. The controllable adhesive force (from 23 μN to 55 μN) can be easily tuned with different number of eggbeater arms for potential applications such as micro hand for droplet manipulation. Furthermore, a new energy‐efficient oil/water separation solution based on our biomimetic structures was demonstrated. The results show that the 3D‐printed eggbeater structure could have numerous applications, including water droplet manipulation, 3D cell culture, micro reactor, oil spill clean‐up, and oil/water separation.
Wet‐Transfer of Freestanding Dense Colloidal Quantum Dot Films and Their Photonic Device Application
Authors: Han Changhyun , Jung Hyunho , Lee Jongho , Lee Myungjae , Park Yeonsang , Cho Kyung‐Sang , Jeon Heonsu
Published: December 2017

A method of wet‐transferring a densely packed colloidal quantum dot (CQD) film is reported herein. Layers of poly(vinyl alcohol) (sacrificial layer) and poly(methyl methacrylate) (temporary mechanical support) are spin‐coated below and above the CQD film, respectively; the two layers are eventually removed, resulting in a single CQD film on an alien substrate. CQD films as large as 1 cm × 1 cm are transferred to any substrate, including flexible and prepatterned ones, with very little mechanical or optical damage. The wet‐transfer method can be repeated to form a CQD heterostructure. A CQD distributed feedback (DFB) laser is also demonstrated by transferring a thick CdSe‐based CQD layer (for both optical gain and waveguiding) on top of a surface grating structure. The resultant CQD structure exhibits a single‐mode DFB lasing action, with a high spontaneous emission factor (β ≈ 10−3), owing to a strong vertical mode confinement and smooth surface morphologies on both sides of the CQD waveguide layer.
Room‐Temperature Red–Green–Blue Whispering‐Gallery Mode Lasing and White‐Light Emission from Cesium Lead Halide Perovskite (CsPbX3, X = Cl, Br, I) Microstructures
Authors: Guo Pengfei , Hossain Mohammad Kamal , Shen Xia , Sun Haibin , Yang Wenchao , Liu Chaoping , Ho Chun Yuen , Kwok Cheuk Kai , Tsang Sai‐Wing , Luo Yongsong , Ho Johnny C. , Yu Kin Man
Published: December 2017

Wavelength‐tunable nano/microlasers are essential components for various highly integrated and multifunctional photonic devices. Based on the different band gap/composition of inorganic cesium lead halide perovskite materials, broad band light absorption and emission devices can be achieved. Herein, a vapor–liquid–solid route for growing cesium lead halide perovskite (CsPbX3, X = Cl, Br, I) microcrystal structures is demonstrated. These square‐shaped microstructures exhibit strong blue, green, and red photoluminescence, indicating that their band gaps can be engineered to cover the entire visible range. Optically pumped red–green–blue whispering‐gallery mode lasers based on the controlled composition of these microcrystals are successfully realized at room temperature. Moreover, rationally designed white‐light‐emitting chips with high brightness are fabricated utilizing these metal halide perovskite microstructures grown on sapphire. All these results evidently suggest a feasible route to the design of red–green–blue lasers and white‐light emitters for potential applications in full‐color displays as well as photonic devices.
Potassium Ion Assisted Synthesis of Organic–Inorganic Hybrid Perovskite Nanobelts for Stable and Flexible Photodetectors
Authors: Zhu Bai‐Sheng , He Zhen , Yao Ji‐Song , Chen Chen , Wang Kun‐Hua , Yao Hong‐Bin , Liu Jian‐Wei , Yu Shu‐Hong
Published: December 2017

Low‐dimensional organic–inorganic hybrid perovskites with controllable morphologies are attractive for high‐performance optoelectronic devices. In particular, the 1D organic–inorganic hybrid perovskite nanowires/nanobelts are promising for flexible photodetectors due to high photoresponsivity and strain endurance capability. Herein, a novel and large‐scale synthesis of (C4H9NH3)2PbBr4 organic–inorganic hybrid perovskite nanobelt achieved by the potassium ions assisted controllable crystal growth during the precipitation process in solutions is reported. The obtained (C4H9NH3)2PbBr4 perovskite nanobelts exhibit high‐efficient photoluminescence and superior stability under ambient conditions. Furthermore, these nanobelts are used as photoresponsive materials to fabricate flexible photodetectors, which show much higher switching ratio than that of photodetectors based on (C4H9NH3)2PbBr4 microplatelets. Attractively, after repeated bending for 1000 times, the nanobelt‐based photodetector only shows less than 10% decay in switching ratio in contrast to at least 40% of switching ratio decay for the microplatelets‐based photodetector. The reported potassium ion assisted large‐scale synthesis of (C4H9NH3)2PbBr4 nanobelts paves a new avenue for the application of organic–inorganic hybrid perovskites in flexible optoelectronic devices.
Dynamically Tunable Deep Subwavelength High‐Order Anomalous Reflection Using Graphene Metasurfaces
Authors: Wang Chao , Liu Wenwei , Li Zhancheng , Cheng Hua , Li Zhi , Chen Shuqi , Tian Jianguo
Published: December 2017

Graphene‐based metasurfaces have emerged as promising photoelectric devices that can dynamically control the behavior of electromagnetic waves. The high‐order anomalous reflection provides an additional degree of freedom in the field of photonic research. Here, a series of gradient graphene metasurfaces with high‐order modes to manipulate the wavefront of reflected light is proposed. By properly arranging the graphene nanostructures, 5‐order anomalous reflection and 15‐order high‐quality Laguerre–Gaussian beams are achieved. Furthermore, the efficiency of the metasurfaces is dynamically controlled by tuning the electrostatic gating to change the Fermi energy of graphene. This work offers a new idea for the development of tunable wavefront‐controlling devices and contributes to a wide range of applications in photonic systems.
Nanosizing Ammonia Borane with Nickel: A Path toward the Direct Hydrogen Release and Uptake of BNH Systems
Authors: Lai Qiwen , Rawal Aditya , Quadir Md Zakaria , Cazorla Claudio , Demirci Umit B. , Aguey‐Zinsou Kondo‐Francois
Published: December 2017

Ammonia borane (AB), with one of the highest hydrogen content (19.6 mass%), has attracted much attention as a potential hydrogen storage material. However, its complex and multistep thermal decomposition process has left the idea that AB can only be an irreversible hydrogen storage material. Herein, we demonstrate the potential of a novel nanosizing strategy in overcoming current drawbacks. By (a) successfully restricting the particle size of AB to the nanoscale (≈50 nm), and (b) discreetly encapsulating the synthesised nanosized AB particles within a nickel (Ni) matrix, AB showed unforeseen hydrogen reversibility along its decomposition path. Owing to the catalytic effect of Ni and the embedment of AB with the Ni matrix, this nanosizing approach reduced the hydrogen release temperature, suppressed the melting of AB and the production of volatiles by‐products including diborane and borazine. But more remarkably, this approach enabled the reversible release and uptake of pure hydrogen at 200 °C and 6 MPa H2 pressure, only. Reversibility is thought to occur through an iminoborane oligomer resulting from the initial decomposition of the nanosized AB/Ni matrix. This result demonstrates for the first time the possibility of tailoring.
Multilayered Flexible Fibers with High Performance for Wearable Supercapacitor Applications
Authors: Garcia‐Torres Jose , Crean Carol
Published: December 2017

Multilayered flexible fibers, consisting of carbon black–carbon nanotube fibers, manganese oxides, and conducting polymers, are fabricated for use as electrodes in supercapacitors. Carbon‐based fibers are initially prepared by wet‐spinning using carbon‐based nanomaterials (carbon black and carbon nanotubes) and chitosan as a matrix. Subsequent coatings with manganese oxides and conducting polymers form a multilayered structure. Different MnO2 crystalline structures (ε‐MnO2, γ‐MnO2) are grown onto the fiber by electrodeposition and different conducting polymers (polyethylenedioxythiophene and polypyrrole) used as a conductive wrapping. Each layer improves the performance of the fiber by adding different functionalities. While MnO2 improves the capacitance of the fiber, the presence of conducting polymers creates a conductive network increasing the capacitance further and conferring cycling stability. Capacitance values up 600 F g−1 and capacitance retention of 90% can be achieved with these multilayered hybrid fibers. A symmetric supercapacitor device, prepared from two hybrid fibers, shows no significant change in properties when the device is bent, demonstrating their potential in flexible electronic devices and wearable energy systems.
High‐Performance Activated Carbons Synthesized from Nanocellulose for CO2 Capture and Extremely Selective Removal of Volatile Organic Compounds
Authors: Xu Chao , Ruan Chang‐Qing , Li Yunxiang , Lindh Jonas , Strømme Maria
Published: December 2017

A series of sustainable activated carbons (ACs) with large surface areas and tunable pore sizes is synthesized from Cladophora cellulose and its chemically modified derivatives in a one‐step physical carbonization/activation process. The molecular structure of the cellulose precursors and the carbonization/activation atmosphere (N2 or CO2) significantly influence the pore structure of the ACs. When using oxidized cellulose and its further cross‐linkages as the precursor, the ACs have a large volume of ultramicropores (pore diameter < 0.8 nm). Activation in CO2 results in ACs with surface areas up to 1241 m2 g−1. These ACs have a high CO2 uptake capacity (2.29 mmol g−1 at 0.15 bar, 5.52 mmol g−1 at 1 bar; 273 K) and a high CO2–over–N2 selectivity (42 at 273 K). In addition, the capacity of the ACs to adsorb vapors of volatile organic compounds (VOCs) is remarkable, with values up to 0.97 mmol g−1 at very low VOC concentrations (200 ppmv). The ACs have ultrahigh VOCs–over–N2 selectivity up to 9.35 × 103 at 293 K for 0.02 vol%/99.8 vol% of benzene/N2 mixture. It is anticipated that these ACs will be useful as sorbents for the postcombustion capture of CO2 and for indoor removal and direct air capture of various VOCs.
Hydrolytically Stable MOF in 3D‐Printed Structures
Authors: Halevi Oded , Tan Joel M. R. , Lee Pooi See , Magdassi Shlomo
Published: December 2017

Metal–organic frameworks (MOFs) are a well‐developed field of materials, having a high potential for various applications such as gas storage, water purification, and catalysis. Despite the continuous discoveries of new MOFs, so far there are only a limited number of industrial applications, partially due to their low chemical stability and limited mechanical properties, as well as difficulties in integration within functional devices, Herein, a new approach is presented toward the fabrication of MOF‐based devices, utilizing direct 3D printing. By this method, 3D, flexible, and hydrolytically stable MOF‐embedded polymeric structures are fabricated. It is found that the adsorption capacity of the 3D‐printed MOF is retained, with significantly improved hydrolytic stability of the printed MOFs (copper benzene‐1,3,5‐tricarboxylate) compared to the MOF only. It is expected that applying 3D printing technologies, for the fabrication of functional MOF objects such as filters and matrices for columns and flow reactors, will open the way for utilization of this important class of materials.