Direct synthesis of ultralight, elastic, high-temperature insulation N-doped TiO2 ceramic nanofibrous sponges via conjugate electrospinning.

The design of three-dimensional ceramic nanofibrous materials with high-temperature insulation and flame-retardant characteristics is of significant interest due to the effectively improved mechanical properties. However, achieving a pure ceramic monolith with ultra-low density, high elasticity and toughness remains a great challenge. Herein, a low-cost, scalable strategy to fabricate ultralight and mechanically robust N-doped TiO2 ceramic nanofibrous sponges with a continuous stratified structure by conjugate electrospinning is reported. Remarkably, the introduction of dopamine into the precursor nanofibers is engineered, which realizes the nitrogen doping to inhibit the TiO2 grain growth, endowing single nanofibers with a smoother, less defective surface. Besides, the self-polymerization process of dopamine allows the construction of bonding points between nanofibers and optimizes the distribution of inorganic micelles on polymer templates. Moreover, a rotating disk receiving device under different rotating speeds is designed to obtain N-doped TiO2 sponges with various interlamellar spacings, further affecting the maximum compressive deformation capacity. The resulting ceramic sponges, consisting of fluffy crosslinked nanofiber layers, possess low densities of 12-45 mg cm-3, which can quickly recover under a large strain of 80% and have only 9.2% plastic deformation after 100 compression cycles. In addition, the sponge also exhibits a temperature-invariant superelasticity at 25-800 °C and a low heat conductivity of 0.0285 W m-1 K-1, with an outstanding thermal insulation property, making it an ideal insulation material for high-temperature or harsh conditions.

Recent progress in TiO2-based microwave absorption materials.

It is particularly important to develop high-performance microwave absorption (MA) materials to remediate the increasingly serious electromagnetic pollution. Recently, titanium dioxide-based (TiO2-based) composites have become a research hotspot owing to their light weight and synergy loss mechanism. In this study, significant research progress in TiO2-based complex-phase microwave absorption materials is reviewed, which involves carbon components, magnetic materials, polymers and so on. First, the research background and limitations of TiO2-based composites are discussed. The design principles for microwave absorption materials are elaborated in the next section. More importantly, TiO2-based complex-phase materials with multi-loss mechanisms are analyzed and summarized in this review. Finally, the conclusions and prospectives are presented, which provide a reference for the understanding of TiO2-based MA materials.

A functional study of zinc-titanium coatings and exploration of the intrinsic correlation between angiogenesis and osteogenesis.

With the development of implant applications, osseointegration has become a criterion for implant success. A good blood supply is essential for successful osseointegration. To improve the pro-angiogenic ability of the implants, in this experiment we introduced zinc into the titanium coating. The physical morphology, biocompatibility, pro-angiogenic ability, and osteogenic effect of the zinc-containing titanium coatings were investigated. The pro-angiogenic effect of zinc ions was determined, and the intrinsic link between angiogenesis and osteogenesis under the effect of zinc ions was investigated. Zinc-containing titanium coating was prepared using a micro-arc oxidation (MAO) technique. The physical properties of the coating materials were determined by analyzing the microstructure, roughness, hydrophilic properties, constituent elements, and ionic release of the coating. The biocompatibility of the coating materials was examined using apoptosis and proliferation assays of human umbilical vein endothelial cells (HUVECs). The pro-angiogenic function and osteogenic ability of the zinc-containing coating were investigated by CD31 immunofluorescence staining and quantitative polymerase chain reaction (q-PCR) assay. The optimal concentration of zinc ions for pro-angiogenesis was screened by ion assay. Conditioned media (CM) were prepared for the experiments. The intrinsic link between angiogenesis and osteogenesis was determined by q-PCR to detect the expression of genes related to HUVECs and BMSCs after culture in CM. The prepared Zn-containing micro-arc oxide coatings were shown to have good physical properties, stable Zn2+ release ability, and biocompatibility, as well as good angiogenic and osteogenic potential. In addition, ion experiments confirmed that 60 µM Zn2+ exhibited the best angiogenic effect; more importantly, a mutual promotion between angiogenesis and osteogenesis regeneration in the Zn2+ microenvironment was also found. The introduction of Zn2+ improved the implants' functionality and laid the foundation for the clinical application of Zn2+ pro-angiogenesis.

Nature-Skin-Derived e-Skin as Versatile "Wound Therapy-Health Monitoring" Bioelectronic Skin-Scaffolds: Skin to Bio-e-Skin.

Electronic skins (e-skins) have the potential to turn into breakthroughs in biomedical applications. Herein, a novel acellular dermal matrix (ADM)-based bioelectronic skin (e-ADM) is used to fabricate versatile "wound therapy-health monitoring" tissue-nanoengineered skin scaffolds via a facile "one-pot" bio-compositing strategy to incorporate the conductive carbon nanotubes and self-assembled micro-copper oxide microspheres with a cicada-wing-like rough surface and nanocone microstructure. The e-ADM exhibits robust tensile strength (22 MPa), flexibility, biodegradability, electroactivity, and antibacterial properties. Interestingly, e-ADM exhibits the pH-responsive ability for intelligent command between sterilization and wound repair . Additionally, e-ADM enables accurate real-time monitoring of human activities, providing a novel flexible e-skin sensor to record injury and motions. In vitro and in vivo experiments show that with electrical stimulation, e-ADM could prominently facilitate cell growth and proliferation and further promote full-thickness skin wound healing, providing a comprehensive therapeutic strategy for smart sensing and tissue repair, guiding the development of high-performance "wound therapy-health monitoring" bioelectronic skin-scaffolds.

The Effects of Chronic Lead Exposure on Testicular Development of Japanese Quail (Coturnix japonica): Histopathological Damages, Oxidative Stress, Steroidogenesis Disturbance, and Hypothalamus-Pituitary-Testis Axis Disruption.

Lead (Pb) becomes a global public health concern for its high toxicology. Birds are sensitive to environmental pollution and Pb contamination exerts multiple negative influences on bird life. Pb also impacts on avian reproductive system. Thus, in this study, we attempted to determine toxicological effects and possible mechanistic pathways of Pb on avian testicular development by using the model species-Japanese quail (Coturnix japonica). Male quail chicks of 1-week-old were exposed to 0, 50, 500, and 1000 ppm Pb concentrations in drinking water for 5 weeks when reaching sexual maturation. The results showed that high Pb doses (500 and 1000 ppm) induced testis atrophy and cloacal gland shrinkage. Microstructural damages of both hypothalamus and testis indicated the disruption of the hypothalamus-pituitary-gonadal (HPG) axis by Pb exposure. The decrease of gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) and testosterone (T) may also imply HPG axis disruption. Moreover, excess testicular oxidative damages featured by increasing reactive oxygen species (ROS) and malondialdehyde (MDA) and decreasing catalase (CAT), glutathione (GSH), superoxide dismutase (SOD), glutathione-S-transferase (GST), and total antioxidant capacity (T-AOC) indicated increasing risks of reproductive dysfunction by Pb. Furthermore, increasing apoptosis and upregulation of gene expression associated with cell death suggested testicular abnormal development. In addition, molecular signaling involved with steroidogenesis in the testis was disturbed by Pb treatment. The study showed that Pb could impair testicular development and reproductive function by morphological and histological injury, hormone suppression, oxidative stress, cell death, and HPG axis disruption.

Inhibition of Inflammatory Response and Promotion of Osteogenic Activity of Zinc-Doped Micro-Arc Titanium Oxide Coatings.

An early and sustained immune response can lead to chronic inflammation after the implant is placed in the body. The implantable materials with immunomodulatory effects can reduce the body's immune response and promote the formation of ideal osseointegration between the implants and bone tissue. In this study, zinc-coated titanium micro-arc oxide coating was prepared on titanium surface by micro-arc oxidation. The physical properties, anti-inflammation, and osteogenesis of the material were evaluated. We have physically characterized the surface structure of the coatings by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and atomic force microscopy (AFM) and detected the release of Zn2+ from the coating surface by inductively coupled optical plasma emission spectrometry (ICP-OES). The BMSCs were inoculated on the surface of the coating, and the biocompatibility of the coating was evaluated by CCK-8 analysis and living and dead cell staining. The osteogenic effect of the layer on BMSCs was evaluated by alkaline phosphatase (ALP) assays, osteocalcin (OCN) immunofluorescence, and quantitative polymerase chain reaction (q-PCR). The survival status of RAW264.7 on the coating surface and the mRNA expression of the associated proinflammatory markers, tumor necrosis factor-α (TNF-α), cluster of differentiation 86 (CD86), and inducible nitric oxide (INOS) were detected by CCK-8 analysis and q-PCR. In parallel, the cell counting kit-8 (CCK-8) analysis and q-PCR screened and evaluated the effective concentration of Zn2+ anti-inflammatory in vitro. The results show that the coating has good physical characterization, and Zn is uniformly bound to the surface of titanium and shows stable release and good biocompatibility to BMSCs, downregulating the expression of inflammation-related genes promoting the bone formation of BMSCs. We have successfully prepared zinc-coated micro-arc titanium oxide coating on the titanium surface, which has good osteogenesis and great anti-inflammatory potential and provides a new way for osseointegration in the implant.

Vitamin C Promotes Apoptosis and Cell Cycle Arrest in Oral Squamous Cell Carcinoma.

Oral squamous cell carcinoma (OSCC) is currently ranked as the eighth most prevalent type of cancer. Despite recent advances in cancer research, the 8-year survival rate for oral squamous cell carcinoma remains only 50-60%. Therefore, markers for early detection, identification of efficient chemotherapeutic agents, and post-therapeutic monitoring are the immediate needs. With this background, this study was designed to investigate the anticancer effects of vitamin C (VC) in oral squamous cell carcinoma. Our results showed that VC had an anticancer effect on the oral squamous cell lines used in this study. VC also showed an inhibitory effect on xenograft tumors in nude mice in vitro and had a synergistic effect with cisplatin to induce cell apoptosis. Mechanistically, VC caused a significant increase in the levels of reactive oxygen species (ROS), which led to induced genotoxic (DNA damage) and metabolic (ATP depletion) stresses, inhibited Bcl-2 expression, and promoted Bax expression and caspase-3 cleavage. VC also caused cell cycle arrest at the G0/G1 phase in OSCC cells, which is related to the activation of tumor suppressor p53 and cyclin-dependent kinase inhibitor p21. In conclusion, VC bears considerable therapeutic potential for the treatment of oral squamous cell carcinoma.

MiR-503-5p functions as an oncogene in oral squamous cell carcinoma by targeting Smad7.

BACKGROND: Oral squamous cell carcinoma (OSCC) is a common oral malignancy. Previous studies indicated that the level of miR-503-5p was upregulated in OSCC tissues. However, the mechanism by which miR-503-5p regulates the proliferation and invasion of OSCC cells remains unclear. Therefore, this study aimed to investigate the role of miR-503-5p during the progression of OSCC. METHODS: The level of miR-503-5p in Tca8113 cells was detected using RT-qPCR assay. In addition, CCK-8, transwell assays and flow cytometry assays were conducted to detect cell viability, migration, invasion and apoptosis, respectively. Meanwhile, the dual luciferase reporter assay was applied to explore the interaction between miR-503-5p and Smad7 in Tca8113 cells. RESULTS: Overexpression of miR-503-5p significantly promoted the proliferation, migration and invasion of Tca8113 cells, while downregulation of miR-503-5p markedly inhibited proliferation, migration and invasion of cells. In addition, knockdown of miR-503-5p obviously induced the apoptosis of Tca8113 cells via increasing the levels of Bax and cleaved caspase 3, and decreased the expression of Bcl-2. Moreover, SMAD family member 7 (Smad7) was identified as a direct binding target of miR-503-5p in Tca8113 cells. Overexpression of miR-503-5p significantly downregulated the levels of Smad7 and E-cadherin, but upregulated the levels of N-cadherin and MMP-9 in Tca8113 cells. CONCLUSION: These results indicated that miR-503-5p might act as an oncogene in OSCC cells by targeting Smad7. Therefore, miR-503-5p might act as a novel and potential therapeutic target for the treatment of OSCC.

Multicolorfully probing intramolecular G-Quadruplex tandem interface.

A long guanine-rich oliogonucleotide sequence can form multiple G-quadruplex (G4) tandem individuals in a single molecule with internal G4-G4 (inG4-G4) interfaces. The interface can exist at the stacked (s-inG4-G4) or unstacked (us-inG4-G4) state, dependent of the G4 conformation and environment. Because of the vital bioactivity of the G4 interface state, there is a great demand for developing a reliable multicolor fluorescence method to identify the interface state using a fluorophore that can emit at the individual wavelength for a specific interface. Herein, we found that a porphyrin with four dihydroxyphenyl substituents (OH2PP) can multicolorfully recognize the s-inG4-G4 dimer interface against the us-inG4-G4 dimer one. The s-inG4-G4 dimer cause significant red shifts in the excitation and emission bands of OH2PP in contrast to the us-inG4-G4 dimer and G4 monomers. OH2PP adopts a 1:1 binding mode with the s-inG4-G4 dimer, whereas a 2:1 binding mode occurs to the us-inG4-G4 dimer. The limit of detection (LOD) for the s-inG4-G4 structure is about tens of nM level. The observed binding dependence of OH2PP on the linker length between the G4 individuals suggests the interface binding with the s-inG4-G4 dimer. Deformation of the porphyrin macrocycle within the s-inG4-G4 interface confinement most likely contributes to the multicolorful response with the hyperporphyrin effect. Our work demonstrates that OH2PP is a promising fluorophore to fluorescently recognize the G4 multimer with an ideal interface-sensitive multicolor response.

A Fluorescently Ratiometric Natural Probe for Selective Detection of Sulfur Dioxide Derivative and Host-Guest Supramolecular Regulation.

Natural sanguinarine (SG) was first used as a fluorescent probe to develop a novel ratiometric sensor for selective HSO3- detection. The nucleophilic addition reaction of HSO3- occurs at the C=N+ group of SG, and subsequent breakage of the conjugated π cycle leads to a decrease in the SG iminium fluorescence that is accompanied by an increase in the alkanolamine fluorescence. Therefore, a ratiometric fluorescence method with a large wavelength shift can be established for HSO3- detection. Furthermore, cucurbit[8]uril was used as an efficient host to encapsulate SG for an improved selectivity for HSO3- detection over H2S. Our method benefits include little interference from other common anions and cations for HSO3- detection, suggesting a promising application in real sample analysis. Besides sensor development, the interaction of the natural SG with HSO3- was first demonstrated in this work to further get an insight into SG's pharmacology.

Polarity inversion sensitized G-quadruplex metal sensors with K+ tolerance.

Due to the high abundance of K+ in environments and K+-induced high stability of G-quadruplex (G4), developing a selective G4-based fluorescent sensor for other metal ions with K+ tolerance is a great challenge. Herein, we found that even in the presence of 15000-fold excess of K+, Ba2+ exhibits a highly specific binding with a human telomeric G4 (htG4) in comparison with other G4-binding metal ions such as Pb2+ and Sr2+. This specific binding event can be recognized by a natural fluorophore of hypericin with a lighting-up fluorescence response. Interestingly, inverting the polarity of the most 3' G in htG4 can sensitize the Ba2+ response with the retaining Ba2+ specificity and K+ tolerance. This polarity inversion of htG4 causes a G4 conformation change in K+ and the polarity-inverted htG4 tends to favorably dimerize in response to the Ba2+ specific binding. To our knowledge, this is the first report that polarity inversion of G4 can be applied to construct a selective metal sensor with K+ tolerance. Our findings will open a new way to conveniently regulate the G4 conformation and stability by polarity inversion towards developing high-performance sensors.

Fluorescently probing site-specific and self-catalyzed DNA depurination.

Depurination occurs via hydrolysis of the purine-deoxyribose glycosyl bond and causes nucleic acid damage. In particular, the DNA sequences that can undergo a self-catalyzed depurination (SCD) will cause a great uncertainty in duplicating, separating, purifying, and storing the DNA samples. Therefore, there is a great demand to develop a rapid detection method for SCD events. Herein, the use of a convenient fluorescence method to follow the site-specific SCD was demonstrated. We found that the resultant apurine site (AP site) from depurination can be selectively recognized by a fluorescent probe of palmatine (PAL) with a turn-on fluorescence response. The dependence of SCD on the bases of the depurination site, pH, metal ions, and time shows that our method can be used to rapidly evaluate the depurination process. Furthermore, the depurination process can be photo-switched using a photoacid as an external initiator. Our work will find wide applications in preliminarily identifying the DNA depurination.

Regular Music Exposure in Juvenile Rats Facilitates Conditioned Fear Extinction and Reduces Anxiety after Foot Shock in Adulthood.

Music exposure is known to play a positive role in learning and memory and can be a complementary treatment for anxiety and fear. However, whether juvenile music exposure affects adult behavior is not known. Two-week-old Sprague-Dawley rats were exposed to music for 2 hours daily or to background noise (controls) for a period of 3 weeks. At 60 days of age, rats were subjected to auditory fear conditioning, fear extinction training, and anxiety-like behavior assessments or to anterior cingulate cortex (ACC) brain-derived neurotrophic factor (BDNF) assays. We found that the music-exposed rats showed significantly less freezing behaviors during fear extinction training and spent more time in the open arm of the elevated plus maze after fear conditioning when compared with the control rats. Moreover, the BDNF levels in the ACC in the music group were significantly higher than those of the controls with the fear conditioning session. This result suggests that music exposure in juvenile rats decreases anxiety-like behaviors, facilitates fear extinction, and increases BDNF levels in the ACC in adulthood after a stressful event.

Mechanisms and modeling of electrohydrodynamic phenomena.

The purpose of this paper is to review the mechanisms of electrohydrodynamic (EHD) phenomenon. From this review, researchers and students can learn principles and development history of EHD. Significant progress has been identified in research and development of EHD high-resolution deposition as a direct additive manufacturing method, and more effort will be driven to this direction soon. An introduction is given about current trend of additive manufacturing and advantages of EHD inkjet printing. Both theoretical models and experiment approaches about the formation of cone, development of cone-jet transition and stability of jet are presented. The formation of a stable cone-jet is the key factor for precision EHD printing which will be discussed. Different scaling laws can be used to predict the diameter of jet and emitted current in different parametrical ranges. The information available in this review builds a bridge between EHD phenomenon and three-dimensional high-resolution inkjet printing.

Target-switched triplex nanotweezer and synergic fluorophore translocation for highly selective melamine assay.

This paper describes a triplex DNA nanotweezer to specifically capture melamine (MEL). The triplex-forming oligonucleotide (TFO) arm can be switched from the open state to the closed state once MEL binds to the abasic site (AP site) in duplex via the bifacial hydrogen bonding with thymines. Following this nanotweezer operation, the AP site-bound fluorophore is translocated to the terminal triplet to subsequently light up the nanotweezer. The TFO arm is found to be pivotal for permitting the AP site binding. The synergic processes of target competition and fluorophore translocation support a high selectivity for the MEL assay even against the inherent adenosine and the MEL hydrolysis products. Chelerythrine is employed as the fluorescent probe. The detection limit of MEL was estimated to be about 140 nM assuming a signal-to-noise ratio of 3. It was applied to the determination of MEL in spiked milk samples without any separation procedure. Conceivably, this method opens a new avenue towards highly selective triplex-based sensors by making use of other commercially available DNA modifications for recognizing other analytes. Graphical abstract Schematic presentation of a triplex nanotweezer with an open-to-close conversion upon the abasic site binding of melamine. The assay is based on a synergic fluorophore translocation. The corresponding duplex otherwise shows no binding with melamine. Chelerythrine (CHE) with a yellow-green emission peaking at 544 nm is employed as the fluorescent probe.

Supramolecularly Multicolor DNA Decoding Using an Indicator Competition Assay.

Relative to the individual intensity-dependent strategy, the multicolor fluorescence sensor has promise to achieve a high signaling contrast. In this work, we develop a cucurbituril-based supramolecular and multicolor DNA recognition rationale via indicator competition assay (ICA). Alkaloids of coptisine (COP) and palmatine (PAL) are identified as the proof-of-principle indicators with a lighting-up fluorescence upon supramolecular complexation to cucurbit[7]uril (CB[7]). With an introduced abasic site (AP site) as the contestant, DNAs having pyrimidines opposite this site can compete for COP with CB[7] to bring an emission color change from green to yellow brown, while those having purines opposite the AP site do not compete for COP and still have the green emission, indicative of a high selectivity for the multicolor nucleotide transversion recognition. However, because of the relatively weaker binding of PAL with CB[7], the AP site-containing DNA can take away PAL from its CB[7] complex and resultantly bring a blue-to-green emission color change independent of the AP site-opposite nucleotide identity, dissimilar to the remaining blue color for the fully matched DNA without the AP site, suggesting a preferable strategy for the AP site biomarker detection. Our method demonstrates a new way to develop an ICA-based multicolor DNA sensor with the supramolecular cucurbituril complexation to ensure a highly selective performance.

Structuring polarity-inverted TBA to G-quadruplex for selective recognition of planarity of natural isoquinoline alkaloids.

Efficient structuring of DNA by small molecules is very crucial in developing DNA-based novel switches with an ideal performance. In this work, we found that inverting only the polarity of the 3' terminal guanine of the thrombin-binding aptamer (3iTBA) totally eradicates the original TBA G-quadruplex (G4) structure in K+. The unstructured 3iTBA can be further refolded upon specifically interacting with small molecules of natural isoquinoline alkaloids (IAs) due to their fruitful binding patterns with variant nucleic acid structures. We identified that 3iTBA can serve as a topology selector for planar IAs. Nitidine (NIT), owing to the planar aromatic ring and coplanar substituents, is the most efficient to restructure the 3iTBA random coil toward the anti-parallel G4 conformation. However, common metal ions can't realize this structuring. The topology selector competency of 3iTBA toward IAs' planarity can be visualized using gold nanoparticles (AuNPs) as the chromogenic readout. Our work expands the G4 repertoire by exploring the polarity inversion regulation and provides a new approach to switch nucleic acid structures toward a small molecule structure-sensitive sensor.

G-Quadruplex DNA with an Apurinic Site as a Soft Molecularly Imprinted Sensing Platform.

Molecularly imprinted polymers (MIPs) provide versatile sensor platforms to recognize targets by shape complementarity. However, the rigid structure of the classic MIPs compromises the signal transduction with necessary polymer and target modifications. Herein, we tried to use a flexible DNA that has a perfectly structured folding as the soft molecularly imprinted polymer (SMIP) for a straightforward sensor. As a proof of concept, the guanosine SMIP recognition was achieved by removal of a guanosine from a G-quadruplex-forming sequence (G4). The G4 folding structure with such an apurinic site (AP site) provides a well-defined MIP binding accommodation for guanosine according to the shape complementarity. The guanosine binding at the AP site subsequently leads to a conformation change suitable for remote readout using a G4-specific fluorescent ligand. The G4 sequence and AP site position were optimized for this SMIP behavior. Due to the G4 compact structure and the remaining hydrogen bonding pattern, nucleosides other than guanosine and negatively charged nucleotides exhibit no binding with the AP site, suggesting a high selectivity in the SMIP recognition. The proposed rationale was then convinced by the alkaline phosphatase-catalyzed GMP hydrolysis. Our work will inspire more interest in exploring nucleic acids as the SMIP frameworks due to their variant conformations and well-established molecular engineering.