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Different concentrations (0, 1 mol%, 2 mol%, 6 mol% and 8 mol%) of palladium (Pd) nanoparticles modified hematite nanofibers (Pd NPs@ $\alpha $ -Fe2O3 NFs) were successfully synthesized via a facile electrospinning method followed by the calcination treatment. Their surface morphologies, crystal structures and chemical compositions were subsequently characterized in order to find optimum modification percentage. The gas sensing experiments on Pd NPs@ $\alpha $ -Fe2O3-based gas sensors revealed that encapsulation of Pd NPs into $\alpha $ -Fe2O3 NFs could significantly improve their sensing performances. Specifically, the as-prepared Pd4/Fe gas sensor exhibited higher response ( $\text{R}_{air}/\text{R}_{gas} =16.6$ ) toward 100 ppm acetone at 220°C, which was 3.4 times higher than that of Pd0/Fe sensor (4.89). Meanwhile, the Pd4/Fe sensor also showed shorter response/recovery (4 s/4 s), low limit of detection (LOD) (50 ppb) and good selectivity and long-term stability. The enhanced gas sensing properties of Pd NPs@ $\alpha $ -Fe2O3-based gas sensors could be attributed to the chemical and electronic sensitization of Pd NPs.

In this paper, an ultrahigh sensitive hydrazine electrochemical sensor based on gold nanoparticles integrated into a reduced graphene oxide/nickel foam (AuNPs-rGO@NF) hybrid structure was synthesized using a facile coating and electrochemical deposition method. The morphology and elemental composition of the as-synthesized AuNPs-rGO@NF structure was comprehensively investigated. Both cyclic voltammetry and potential amperometry results show the optimum AuNPs-rGO@NF sensor exhibits excellent electrochemical performances including higher sensitivity (14.635 μA μM−1 cm−2), lower limit of detection (0.056 μM; S/N = 3), wider linear detection range (0.2–200 μM), good selectivity and long-term stability. Meanwhile, the results of real sample analysis indicate the AuNPs-rGO@NF sensor has great potential for practical electrochemical hydrazine sensing applications.

Au nanoparticle (Au NP) modified α-Fe2O3 nanodisk structures are obtained using a facile hydrothermal method and annealing based surface treatment. XRD, EDS, SEM, TEM and XPS are used to characterize the as-prepared samples, showing crystalline structured Au NPs of about 6–16 nm in diameter on the surface of α-Fe2O3 nanodisk structures of about 145 ± 15 nm in diameter. The Au NP modified α-Fe2O3 nanodisk structures are then investigated for acetone detection under different operating temperatures, showing improved gas sensing performance compared to the pure α-Fe2O3 nanomaterial. In particular, under the optimum working temperature (275 °C), the sensor response of Au0.5Fe can reach a sensibility of 19.5 toward 100 ppm acetone, which is about two times higher than that of the pure one. Meanwhile, the Au0.5Fe acetone sensor also exhibits fast response and recovery time (4 s/7 s), good linear relationship (50–5000 ppb), low detection limit (50 ppb), excellent long-term stability and superior selectivity. Finally, the enhanced gas sensing mechanism of Au NP modified α-Fe2O3 nanomaterials can be attributed to the combined action of chemical and electronic sensitization of Au NPs, which are promising as highly sensing materials toward acetone detection.

Corynebacterium pseudotuberculosis (CP) infection in livestock has become highly difficult to control. To decrease the incidence of CP infection, the supplementation of feed with non-antibiotic antibacterial substances is a potential approach. The aim of this study was to assess the effects of sodium butyrate (NaB), a potential alternative to antibiotics, on CP infection in RAW264.7 macrophages and C57BL/6 mice. Our data showed that NaB (2 mM) significantly ameliorated CPinfection in RAW264.7 macrophages and decreased the bacterial load in the spleens of infected mice. By real-time PCR, we found that NaB induced significant decreases in zinc-dependent superoxide dismutase (sodC) and tip protein C (spaC) expression in CP from infected-RAW264.7 cells and in phospholipase D (pld) and spaC expression in CP from the spleens of infected mice. NaB treatment significantly up-regulated cathelicidin-related antimicrobial peptide (cramp) expression in spleens of mice infected with CP. Furthermore, NaB alleviated histopathological changes in spleens of CP-infected mice. In conclusion, NaB ameliorated CP infection in RAW264.7 macrophages and C57BL/6 mice, and these effects may be related to the modulation of sodC, spaC, pld, and cramp expression.

Sphene–titanium oxide composite coatings are prepared by a hybrid technique of microarc oxidation (MAO) and heat treatment on titanium. The average roughness of the MAO coating increases after heat treatment due to the crystallization and crystal growth of the MAO coating. The wetting ability, roughness, phase composition and surface topological structure of the composite coatings have positive effects on the MC3T3-E1 cell attachment, proliferation and alkaline phosphatase activity. The composite coatings do not cause any hemolysis effect. Furthermore, they also do not give rise to any adverse reactions in vivo according to micro-CT images, radiographs and histological analysis. At the same time, the sphene–titanium oxide composite coatings show perfect osseointegration in rabbit tibia in vivo and display the higher interface bonding strength with rabbit tibia compared to the MAO coating without heat treatment, because the composite coatings have higher bioactivity, good cell response and mechanical properties, and so on.

In this paper, we demonstrate the possibility of direct protein sensing beyond the Debye length limit using a molecular-charge-contact (MCC)-based ion-sensitive field-effect transistor (ISFET) sensor combined with a microfluidic device. Different from the MCC method previously reported, biotin-coated magnetic beads are set on the gate insulator of an ISFET using a button magnet before the injection of target molecules such as streptavidin. Then, the streptavidin&mdash, a biotin interaction, used as a model of antigen&mdash, antibody reaction is expected at the magnetic beads/gate insulator nanogap interface, changing the pH at the solution/dielectric interface owing to the weak acidity of streptavidin. In addition, the effect of the pH or ionic strength of the measurement solutions on the electrical signals of the MCC-based ISFET sensor is investigated. Furthermore, bound/free (B/F) molecule separation with a microfluidic device is very important to obtain an actual electrical signal based on the streptavidin&ndash, biotin interaction. Platforms based on the MCC method are suitable for exploiting the advantages of ISFETs as pH sensors, that is, direct monitoring systems for antigen&ndash, antibody reactions in the field of in vitro diagnostics.

Corynebacterium pseudotuberculosis is a prominent human and animal pathogen causing chronic inflammatory diseases. Interleukin-1β (IL-1β) is involved in the response to such pathogenic infections. However, the mechanism by which IL-1β is secreted during C. pseudotuberculosis infection remains unclear. This study aimed to investigate the mechanism underlying IL-1β secretion by macrophages infected with C. pseudotuberculosis. Herein, we firstly revealed that nucleotide-binding oligomerization domain-like receptor family, pyrin domain containing 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC) and caspase-1 (Casp1) play critical roles in IL-1β secretion rather than IL-1β precursor (pro-IL-1β) expression in C. pseudotuberculosis-infected macrophages. Toll like receptor 4 (TLR4) is partially involved in IL-1β secretion, while absent in melanoma 2 (AIM2) is not involved in IL-1β secretion by C. pseudotuberculosis-infected macrophages. In addition, nuclear factor kappa B (NF-κB) and p38 mitogen-activated protein kinases (p38 MAPK) inhibitors almost attenuated IL-1β secretion, implying that NF-κB and p38MAPK pathway are involved in IL-1β secretion in C. pseudotuberculosis-infected macrophages. Furthermore, C. pseudotuberculosis were significantly more numerous in Nlrp3-/-, Asc-/-, and Casp-1-/- macrophages than in WT macrophages at 24 h after infection (P < 0.05), indicating that NLRP3 inflammasome components limit C. pseudotuberculosis replication in macrophages. Together, these data provide novel insights into the mechanisms underlying IL-1β secretion in C. pseudotuberculosis-infected macrophages and further the current understanding of the host pro-inflammatory immune response against this pathogen.

The ZnO quantum dots modified SnO2 hollow nanospheres (ZnO QDs@SnO2 HNSs) hybrid hierarchical structures were fabricated by modifying ZnO QDs on the surface of SnO2 HNSs using precipitation and hydrothermal method. The gas sensors based on ZnO QDs, SnO2 HNSs and ZnO QDs@SnO2 HNSs present superior sensing properties to formaldehyde compared with three other typical indoor volatile organic compounds (VOCs, including formaldehyde, toluene, benzene and ammonia). In particular, the ZnO QDs@SnO2 HNSs based sensor exhibits high response (36.5–50 ppm), good linearity (1−1000 ppm), rapid response/recovery time (9 s/ 10 s), ultra-low limit of detection (LOD, 5 ppb) and excellent long-term stability. The ZnO QDs@SnO2 HNSs hybrid hierarchical structures not only ensure the porosity but also create lots of heterojunctions, which is benefit for improving the gas sensing properties of a gas sensor.

In this study, we report the label-free and reliable detection of allergic response using a cell-coupled gate field-effect transistor (cell-based FET). Rat basophilic leukemia (RBL-2H3) cells were cultured as a signal transduction interface to induce allergic reaction on the gate oxide surface of the FET, because IgE antibodies, which bind to Fce receptors at the RBL-2H3 cell membrane, are specifically cross-linked by allergens, resulting in the allergic response of RBL-2H3 cells. In fact, the surface potential at the FET gate decreased owing to secretions such as histamine from the IgE-bound RBL-2H3 cells, which reacted with the allergen. This is because histamine, as one of the candidate secretions, shows basicity, resulting in a change in pH around the cell/gate interface. That is, the RBL-2H3-cell-based FET used in this study was originally from an ion-sensitive FET (ISFET), whose oxide surface (Ta2O5) with hydroxyl groups is fully responsive to pH on the basis of the equilibrium reaction. The allergic response of RBL-2H3 cells on the gate was also confirmed by estimating the amount of β-hexosaminidase released together with histamine and was analyzed using the electrical properties based on an inflammatory response of secreted histamine with the vascular endothelial cell-based FET. Thus, the allergic responses were monitored in a nonoptical and real-time manner using the cell-based FETs with the cellular layers on the gate, which reproduced the in vivo system and were useful for the reliable detection of the allergic reaction.

The Ca, P, Si and Na incorporated bioactive coatings with double porous structure in macro (50–1000 μm) and micro (0.6–2.0 μm) scales have been successfully formed on Ti surface by a two-step treatment via microarc oxidation (MAO). The results reveal that the microarc oxidation and NO3− ion corrosion activated by plasma are the two key factors for the formation of macropores during the second MAO treatment. Meanwhile, the MAO processing current, mass loss, surface morphology and elemental concentration of the samples are significantly affected by the NaOH concentration in the electrolyte during the second treatment. With increasing of NaOH concentration from 5 to 20 g/L, the mass loss of the two-step MAO treated (TMAO) samples first increases from 4.3 to 6.7%, then decreases to 4.7%. The number of macropores increases dramatically from 26 to 806 mm− 2, but the size of macropores declines gradually in a range of 1000–143 μm with the varied NaOH concentration. Furthermore, an oxide film composed of Ti3O5 is formed on the macropore surface after treating in the electrolyte with 20 g/L NaOH concentration. Additionally, the sample shows apatite inducing-ability evaluated in simulated body fluid immersion.

Bioactive amorphous phase/TiO2 nanocrystal (APTN) composite coatings were fabricated by microarc oxidation (MAO) on Ti. The APTN coatings are composed of much amorphous phase with Si, Na, Ca, Ti and O elements and a few TiO2 nanocrystals. With increasing applied voltage, the micropore density of the APTN coating decreases and the micropore size of the APTN coating increases. The results indicate that less MC3T3-E1 cells attach on the APTN coatings as compared to Ti. However, the APTN coatings greatly enhance the cell proliferation ability and the activity of alkaline phosphatase. The amorphous phase and the concentrations of the released Ca and Si from the APTN coatings during cell culture have significant effects on the cell response.

The amorphous phase/TiO2 nanocrystals (APTN) composited coatings were prepared on Ti implants for biomedical applications. The Ti implants without and with the APTN composited coatings both do not cause any adverse effects after implantation into the rabbit tibia. The osseointegration of Ti implants after covering the APTN coatings is improved pronouncedly, greatly increasing the interface bonding strength between the implants and newly formed bones. In addition, it is interesting that the newly formed bone tissues appear in the micro-pores of the APTN coatings, promoting the interface bonding between the implants and new bones by the mechanical interlock. Moreover, the Ti implant with the APTN coatings formed at higher applied voltage exhibit higher shear strength and displacement during the pushing out experiment probably due to its better osseointegration.

Macroporous Ti with macropores of 50-400 μm size is prepared by sintering Ti microbeads with different diameters of 100, 200, 400, and 600 μm. Bioactive microarc oxidation (MAO) coatings with micropores of 2-5 μm size are prepared on the macroporous Ti. The MAO coatings are composed of a few TiO2 nanocrystals and lots of amorphous phases with Si, Ca, Ti, Na, and O elements. Compared to compact Ti, the MC3T3-E1 cell attachment is prolonged on macroporous Ti without and with MAO coatings; however, the cell proliferation number increases. These results are contributed to the effects of the space structure of macroporous Ti and the surface chemical feature and element dissolution of the MAO coatings during the cell culture. Macroporous Ti both without and with MAO coatings does not cause any adverse effects in vivo. The new bone grows well into the macropores and micropores of macroporous Ti with MAO coatings, showing good mechanical properties in vivo compared to Ti, MAO-treated Ti, and macroporous Ti because of its excellent osseointegration. Moreover, the MAO coatings not only show a high interface bonding strength with new bones but also connect well with macroporous Ti. Furthermore, the pushing out force for macroporous Ti with MAO coatings increases significantly with increasing microbead diameter.