Interfacial Complex Research Articles

Photocatalysis of titanium dioxide modified by catechol-type interfacial surface complexes (ISC) with different substituted groups

Visible-light responsive TiO2 photocatalyst modified by catechol-type interfacial surface complexes (ISC) was designed by the reaction of TiOH moieties with catechol and such derivatives as 3-methoxycatechol involving electron-donating groups (EDG) and 3,4-dihydroxybenzonitrile involving electron-withdrawing groups (EWG). The visible-light response of the ISC is attributed to excitation from the donor levels created in the TiO2 midband. The phenyl-ring-substituted groups strongly influence the electronic structures of the ISC: the catechols with substituted EWG induce an anodic shift of the donor levels accompanied by an enlargement of the energy gaps, compared with catechol without substituted groups. The photocatalytic activities for H2 evolution from triethanolamine aqueous solutions were systematically investigated. It was confirmed that the more anodic the oxidative potentials of photoinduced holes in the ISC are, the higher the photocatalytic activities they exhibit.

Interfacial interactions of hard polyelectrolyte-stabilized luminescent colloids with substrates

Abstract The present work introduces an origin of sensing function of polyelectrolyte-coated colloids based on Tb(III) complexes with calix[4]resorcinarene cavitand bearing four 1,3 -diketone groups at the upper rim. The Tb(III)-centered luminescence of the colloids remains unchanged at pH 3–9, although the Tb(III) complexes are highly pH-dependent in DMF solutions. Both colloidal and luminescent properties of the colloids are stable within one month at least, which reveals stability of complex-based hard nanotemplates and soft polyelectrolyte deposition. The chelating substrates (catechol, tetracycline and fluoroquinolone derivatives) induce quick and reproducible luminescent response of the complex-based colloids without any detectable changes of their colloidal properties. The ternary complex formation at the interface of the colloids is the reason for their luminescent response on the substrates in aqueous solutions. Both the insolubility of the Tb(III)-containing cores and the shielding and/or buffer effect of the polyelectrolyte coating affect the interfacial complex formation, which results in more selective luminescent response of the colloids on the tetracycline and fluoroquinolone antibiotics in comparison with the complexes in solutions.

Global genome and transcriptome analyses of Magnaporthe oryzae epidemic isolate 98-06 uncover novel effectors and pathogenicity-related genes, revealing gene gain and lose dynamics in genome evolution.

Genome dynamics of pathogenic organisms are driven by pathogen and host co-evolution, in which pathogen genomes are shaped to overcome stresses imposed by hosts with various genetic backgrounds through generation of a variety of isolates. This same principle applies to the rice blast pathogen Magnaporthe oryzae and the rice host; however, genetic variations among different isolates of M. oryzae remain largely unknown, particularly at genome and transcriptome levels. Here, we applied genomic and transcriptomic analytical tools to investigate M. oryzae isolate 98-06 that is the most aggressive in infection of susceptible rice cultivars. A unique 1.4 Mb of genomic sequences was found in isolate 98-06 in comparison to reference strain 70-15. Genome-wide expression profiling revealed the presence of two critical expression patterns of M. oryzae based on 64 known pathogenicity-related (PaR) genes. In addition, 134 candidate effectors with various segregation patterns were identified. Five tested proteins could suppress BAX-mediated programmed cell death in Nicotiana benthamiana leaves. Characterization of isolate-specific effector candidates Iug6 and Iug9 and PaR candidate Iug18 revealed that they have a role in fungal propagation and pathogenicity. Moreover, Iug6 and Iug9 are located exclusively in the biotrophic interfacial complex (BIC) and their overexpression leads to suppression of defense-related gene expression in rice, suggesting that they might participate in biotrophy by inhibiting the SA and ET pathways within the host. Thus, our studies identify novel effector and PaR proteins involved in pathogenicity of the highly aggressive M. oryzae field isolate 98-06, and reveal molecular and genomic dynamics in the evolution of M. oryzae and rice host interactions.

Comparative genomics identifies the Magnaporthe oryzae avirulence effector AvrPi9 that triggers Pi9‐mediated blast resistance in rice

We identified the Magnaporthe oryzae avirulence effector AvrPi9 cognate to rice blast resistance gene Pi9 by comparative genomics of requisite strains derived from a sequential planting method. AvrPi9 encodes a small secreted protein that appears to localize in the biotrophic interfacial complex and is translocated to the host cell during rice infection. AvrPi9 forms a tandem gene array with its paralogue proximal to centromeric region of chromosome 7. AvrPi9 is expressed highly at early stages during initiation of blast disease. Virulent isolate strains contain Mg-SINE within the AvrPi9 coding sequence. Loss of AvrPi9 did not lead to any discernible defects during growth or pathogenesis in M. oryzae. This study reiterates the role of diverse transposable elements as off-switch agents in acquisition of gain-of-virulence in the rice blast fungus. The prevalence of AvrPi9 correlates well with the avirulence pathotype in diverse blast isolates from the Philippines and China, thus supporting the broad-spectrum resistance conferred by Pi9 in different rice growing areas. Our results revealed that Pi9 and Piz-t at the Pi2/9 locus activate race specific resistance by recognizing sequence-unrelated AvrPi9 and AvrPiz-t genes, respectively.

Interfacial interactions and complex segmental dynamics in systems based on silica-polydimethylsiloxane core–shell nanoparticles: Dielectric and thermal study

Effects of two types of silica particles, with different characteristics of porosity, on segmental mobility of poly(dimethylsiloxane), PDMS, in core–shell nanocomposites with two contents of polymer, 40 and 80 wt%, were studied by employing thermal (DSC) and dielectric (DRS, TSDC) techniques, under different annealing procedures. Filler morphology and polymer–particle interactions were found to affect PDMS crystallinity and segmental mobility. The dielectric techniques allowed the detection of four contributions to the segmental dynamics associated with the glass transition arising, in the order of decreasing mobility, from confined polymer chains in the pores of silica gel (αp relaxation), from the bulk (unaffected) amorphous polymer fraction (α relaxation), from polymer chains restricted between condensed crystal regions (αc) and from semibound polymer in an interfacial layer close to the nanoparticle surface (α′). For the core–shell nanocomposites with high PDMS content (80 wt%) the interfacial α′ relaxation process is found to have similar characteristics with that in conventional PDMS/silica nanocomposites, for lower PDMS content (40 wt%), however, the interfacial relaxation process exhibits distinct differences. The experimental findings are discussed in terms of models proposed for the description of conformations of polymers adsorbed onto a solid surface.

Effects of sodium dodecyl sulfate on structures of poly(N-isopropylacrylamide) at the particle surface.

The effect of sodium dodecyl sulfate (SDS) on the poly(N-isopropylacrylamide) (PNIPAM) tethered to nanoparticles was experimentally investigated using dynamic light scattering below the lower critical solution temperature. A mean-field analytical model was used to calculate the parameters of interfacial PNIPAM-SDS complexes. Particularly, the magnitude of SDS adsorption energy obtained decreases with decreasing excluded volume parameter, implying that the partially collapsed PNIPAM brush virtually favors the adsorption of SDS onto the PNIPAM chains. A self-consistent field theory (SCFT) model was used to get a detailed quantitative description of monomer density distribution. By lowering the solvent quality, a number of phenomena related to the noncontinuity of monomer density are revealed. These phenomena are either referred to as the vertical phase separation or as its precursor, which can be delayed and eventually eliminated as the SDS coverage is increased. The distribution of free chain ends was calculated using the SCFT model. Increasing the SDS coverage gives rise to a broader and more asymmetric distribution of free chain ends, accompanied by a considerable expansion of the dead zone (below which the free chain ends do not exist), but lowering the solvent quality has opposite influences. The relative thickness of the dead zone can be scaled to a master curve, regardless of SDS coverage.

Double‐layered emulsions as beverage clouding agents

ABSTRACTThere is a constant interest in finding alternatives to gum arabic in flavour and beverage industries. The ability to prepare beverage‐cloud emulsions using a layer‐by‐layer deposition technique was developed with extremely low usage levels of proteins and polysaccharides. Sodium caseinate (S) and β‐lactoglobulin (L) were selected to stabilize the primary emulsions. Polysaccharides of sodium alginate (A), ι‐carrageenan (C), gum arabic (G) and pectin (P) were evaluated as secondary layers. Polysaccharide concentration was optimized based on droplet size and ζ‐potential. The performance of double‐layered emulsions in beverage‐cloud applications was evaluated. Polysaccharide concentration and pH were found critical to the formation of stable multilayered emulsions. Protein and polysaccharide type also impacted droplet size and ζ‐potential of multilayered emulsions. β‐Lactoglobulin was found to be better than sodium caseinate in forming protein–polysaccharide interfacial complexes, as demonstrated by smaller mean droplet diameters (MDD) of L–A, L–P and L–C than those of S–A, S–P and S–C. It was also found that the polysaccharide concentration has to be above a critical value (0.2–0.5 wt% depending on the type of polysaccharides) to prevent multilayered emulsions from bridging flocculation. Data showed that double‐layered emulsions of L–A, L–C and L–G formed by electrostatic deposition could provide the same performance as traditional emulsifiers of gum arabic (G) and modified starch (M). After four weeks of storage at room temperature, beverage clouds stabilized with G, M, L–A, L–C and L–G showed MDDs of 0.68, 0.67, 0.90, 0.82 and 0.65 µm, respectively, and turbidity losses of 18, 28, 22, 19 and 25%, respectively. Copyright © 2014 John Wiley & Sons, Ltd.

Interfacial defect complex at the MgO/SrTiO3heterojunction and its electronic impact

Atomic defects exist in various heterojunctions and can remarkably affect their properties, yet it remains a challenging task to identify each individual defect. Here, by combining advanced transmission electron microscopy, spectroscopy and first-principles calculations, we obtain a structural and element-selective imaging of defects at an interface between MgO and SrTiO3. We demonstrate that even for structurally simple MgO and SrTiO3, their interface involves a defect complex comprising of substitutional Ti and Mg vacancies, which induce a marked shift in electronic states. The Ti atoms diffused into MgO exhibit a valence state of +4 and a certain degree of covalency to the surrounding oxygen. Such an ability to determine defects allows us to precisely alter heterojunctions so as to critically improve the device performances.

Observation of a rare earth ion-extractant complex arrested at the oil-water interface during solvent extraction.

Selective extraction of metal ions from a complex aqueous mixture into an organic phase is used to separate toxic or radioactive metals from polluted environments and nuclear waste, as well as to produce industrially relevant metals, such as rare earth ions. Selectivity arises from the choice of an extractant amphiphile, dissolved in the organic phase, which interacts preferentially with the target metal ion. The extractant-mediated process of ion transport from an aqueous to an organic phase takes place at the aqueous-organic interface; nevertheless, little is known about the molecular mechanism of this process despite its importance. Although state-of-the-art X-ray scattering is uniquely capable of probing molecular ordering at a liquid-liquid interface with subnanometer spatial resolution, utilizing this capability to investigate interfacial dynamical processes of short temporal duration remains a challenge. We show that a temperature-driven adsorption transition can be used to turn the extraction on and off by controlling adsorption and desorption of extractants at the oil-water interface. Lowering the temperature through this transition immobilizes a supramolecular ion-extractant complex at the interface during the extraction of rare earth erbium ions. Under the conditions of these experiments, the ion-extractant complexes condense into a two-dimensional inverted bilayer, which is characterized on the molecular scale with synchrotron X-ray reflectivity and fluorescence measurements. Raising the temperature above the transition leads to Er ion extraction as a result of desorption of ion-extractant complexes from the interface into the bulk organic phase. XAFS measurements of the ion-extractant complexes in the bulk organic phase demonstrate that they are similar to the interfacial complexes.

Role of Metal Cations in Alkali Metal Chloride Doped Graphene

The doping mechanism of graphene with chlorides of low work-function metals was investigated using NaCl, KCl, MgCl2, and CaCl2. After graphene was doped with 1.0 M dopants, the sheet resistance of the graphene increased from 780 Ω sq–1 to 1350–1620 Ω sq–1 after doping. Its transmittance at 550 nm also decreased from 97% to 90–94% owing to the presence of metal particles. The shift of G and 2D peaks in the Raman spectra coincided with n-type doping phenomena. The shift of the peak for the C═C bond to high binding energy and the decrease of the IC═C/IC—C intensity ratio in spectra acquired using synchrotron radiation photoemission spectroscopy (SRPES) provided further evidence of n-type doping. Furthermore, secondary cutoff spectra in SRPES showed that the work function of the doped graphene progressively decreased from 4.32 eV to 3.7, 3.66, 3.81, and 3.9 eV. The formation of interfacial dipole complexes between the oxidized functional group on graphene and metal cations with low work functions is considered to induce n-type doping, resulting in a decrease of both the conductivity and work function of the graphene sheet. Therefore, metal cations may play an important role in an alkali or alkaline metal chloride doping system.

Transient analysis of a single rising bubble used for numerical validation for multiphase flow

Accurate tracking of multiphase interfaces (such as an air bubble in a fluid) is difficult yet significant to many engineering processes. Computationally, various tracking methods have been developed, including the volume of fluid (VOF), and coupled level set and volume of fluid (CLSVOF) methods. In order to accurately assess the small-scale differences between different interface capturing methods, a comprehensive experimental dataset is required for validation, including detailed information describing the interface deformation, and transient development of the stage by stage shape data. These interfacial details are better investigated from a two-dimensional (2D) rather than three-dimensional (3D) comparison, because the computational resources for determining an accurate shape can be maximized, and the interfacial complex deformation is difficult to analyze in 3D. In this paper, the fully developed shape and subsequent deformation of 2D rising bubbles have been captured experimentally and analyzed in detail using image processing. These results are then compared with the corresponding VOF and CLSVOF results, demonstrating the usefulness of the experimental dataset as a validation tool.

Cytotoxic activity of paclitaxel incorporated into polyelectrolyte nanocapsules

Nanoencapsulation is a promising solution for the delivery of chemotherapeutics to tumors. A method of preparation of drug-loaded nanocapsules based on the liquid core encapsulation by a sequential adsorption of a polyelectrolyte is described. An easily evaporative solvent, chloroform, was used as an oil phase. An interfacial complex formed with an oil-soluble, Food and Drug Administration-approved surfactant, and polycation poly-l-lysine (PLL) was used as a microemulsion stabilizer. A polyelectrolyte multilayer shell was constructed by a sequential adsorption of polyelectrolytes using biocompatible polyelectrolytes (PLL as a polycation and poly-l-glutamic acid as a polyanion). A hydrophobic anticancer agent, paclitaxel, was successfully encapsulated in the nanocarriers with the average size of 100 nm. In vitro analysis of the effects of nanoformulations was performed using a mouse colon carcinoma cell line CT26-CEA. Biocompatibility of the nanocapsules was evaluated using various biochemical assays. The results indicate that the cell viability was diminished by positively but not by negatively charged nanocarriers. Analysis of the cellular uptake of nanocapsules determined by flow cytometry and confocal microscopy confirmed their accumulation inside the cells. Encapsulated paclitaxel retains its cytotoxic/cytostatic activity; although its effects were weaker than those of the corresponding concentrations of the free drug. The generated nanocapsules seem to be a valuable vehicle for tumor drug delivery; although further work is needed to increase their overall activity.

Interfacial Shear Rheological Properties of Enhanced Oil Recovery Polymers with Different Structures

The interfacial shear rheological properties of ultra-high molecular weight partialhydrolysis polyacrylamide(PHPAM) and hydrophobically modified polyacrylamide(HMPAM) for enhanced oil recovery(EOR) were studied by biconical method at kerosene-water interfaces. The effects of time,strain amplitude and shear frequency on interfacial shear rheological data of different concentration PHPAM and HMPAM solutions were investigated. The experimental results show that the information for structure of interfacial film can be detected only under optimum shear frequency range. HMPAM molecules have interfacial activity and can adsorb onto the interface,which result in the enhancement of strength of interfacial film with aging time and the viscous nature at higher concentration. PHPAM shows no interfacial activity,which leads to time independence of shear rheological data and the elastic property of film. The interfacial shear complex moduli of HMPPAM are obviously higher than those of PHPAM because the interfacial net structure can be formed by HMPAM molecules through hydrophobic interaction. The experimental results of relaxation method show that the slow relaxation process related to destroy and restructure of interfacial net structure under shear deformation is responsible for the higher strength of HMPAM film.

In Vitro Interaction of Polyelectrolyte Nanocapsules with Model Cells

The nanocapsules based on a liquid core with polyelectrolyte shells prepared by the technique of sequential adsorption of polyelectrolytes (LbL) were investigated to verify capsules bioacceptance. Using AOT (docusate sodium salt) as emulsifier, we obtained liquid cores, stabilized by the interfacial complex AOT/PLL (poly-l-lysine hydrobromide). These liquid cores were encapsulated by sequential adsorption of polyelectrolytes using biocompatible polyanion PGA (poly-l-glutamic acid sodium salt) and biocompatible polycation PLL. The average size of the formed capsules was 60-80 nm. The influence of a number of polyelectrolytes layer in the shell (thickness of polyelectrolytes shell), surface charge, and capsule doses on cell viability was studied in a cellular coculture assay. In order to improve nanocapsules biocompatibility, the PEG-ylated external layers were prepared using PGA-g-PEG (PGA grafted by PEG poly(ethylene glycol)). For the most toxic nanocapsules (with only one polycation layer) about 90% of cells could survive when the concentration of nanocapsules was below 0.2 × 10(6) per one cell. That suggests that they use as a delivery vehicles is quite safe for living cells. Analysis of internalization of AOT(PLL/PGA)4-g-PEG in HEK 293 cells indicates that tested nanocapsules can easily penetrate cells membrane.

Development and Application of Anti-collapse & Anti-drag Agent for Drilling Fluid

Using asphalt as raw material, anti-collapse drag reducing agent GFT with softening point at 35°C is preparedby employing interfacial complexes generation method. The rheological properties and lubrication are measured before and after adding GFT in several water-based drilling fluids. The results show that GFT exhibits the excellent anti-caving and lubricity performance. And GFT could deform into and cement fracture at lower temperature, and then seal off cracks of sidewall, reduce the drilling fluid filtration. When the dosage of GFT is 0.5wt.%, the lubricity coefficient reduced rate of bentonite dispersion is 80.5%. In addition, GFT shows better lubrication performance and effect of reducing filtration loss than commercially available products in the same dose (2wt.%). Eventually, through field application of GFT in Jinchang JCSD-1 borehole and Handan ZK10-2 borehole, the results indicate problems of wellbore collapse and lubricity of drilling fluid have been solved successfully. Consequently, anti-collapse drag reducing agent GFT has a promising potential application for drilling fluids.

Potential-mediated interaction between dextran sulfate and negatively charged phospholipids films at air/water and liquid/liquid interfaces

Abstract The effect of dextran sulfate (DS) on distearoyl phosphatidyl glycerol (DSPG) and distearoyl phosphatidic acid (DSPA) films formed in the presence of Ca2Cl, LiCl or KCl as aqueous electrolytes, was analyzed by cyclic voltammetry, surface pressure-area and surface potential-area isotherms and Brewster angle microscopy. Experiments of cyclic voltammetry at the water/1,2-dichloroethane interface showed an interfacial adsorption/desorption process in the presence of DSPG, or DSPA, DS and LiCl. It is suggested that this process could correspond to the formation of an interfacial complex DS–Li+–DSPG or DS–Li+–DSPA at positive potentials with respect to the potential of zero charge (pzc) and its desorption from the interface towards the aqueous phase, by complex dissociation, at potentials below pzc. The voltammetric analysis of tetraethylammonium (TEA+) cation transfer, from the aqueous to the organic phase, evidenced a blocking effect of DSPG and DSPA films on that process, whose magnitude depends on both the nature of the phospholipids and the cation forming the aqueous electrolyte. The structure and permeability of those films were altered by the presence of DS, by formation of the complex DS–cation–phospholipid, which produces an expansion of the monolayer, whose extent depends on the cation present in water, and the polar head group of the phospholipid. Electrochemical experiments were completed with compression isotherms for DSPG and DSPA monolayers both in the absence and in the presence of DS. In this case, as opposed to the voltammetric results, a negligible effect of DS was observed in the isotherms. This apparent contradiction could be explained considering the effect of polarization, which enables the accumulation of cations at the interface, favouring the formation of the DS–cation–phospholipid complex which is responsible for the increase in the film permeability. Similarly, the thickness values for phospholipid films obtained from the Brewster angle microscopy experiments were the same either in the absence or in the presence of DS at any lateral pressure value, which is a direct evidence of lack of interaction between DS and DSPA or DSPG molecules at open circuit. Therefore, it was concluded that the formation of the complex DS–cation–phosholipid, responsible for the increase in permeability observed in voltammetric experiments, must be attributed to the polarization of the interface. The application of high positive potentials at the interface promotes cations accumulation, which neutralize the negative charge in phosphate groups and in DS and allows their interaction.

Modeling the performance of an ideal NaBH4–H2O2 direct borohydride fuel cell

A 2D direct borohydride fuel cell (DBFC) model has been developed to explore the prospective performance of this technology, for a cell with fast selective electrocatalysts and a selective membrane. In the modeled DBFC, a Nafion membrane in the Na+ form separates flow channels with aqueous fuel (0.1–0.5 M NaBH4/4 M NaOH) and oxidizer (4 M H2O2/4 M H2SO4). Electrochemical reactions occur on catalyst-coated channel walls. The electrocatalysts are selective for complete BH4− oxidation and H2O2 reduction, the reactions have fast forward rate constants, and only Na+ and H2O cross the membrane. The model captures interfacial charge transfer reactions and complex transport in the flow channels and membrane. Results show that current density and voltage efficiency vary by >50% from inlet to outlet due to concentration boundary layer development. The BH4− concentration boundary layer limits peak power density, despite migration and fuel utilizations below 10%. Power density increases with BH4− inlet concentration and fuel flow rate, but at the expense of lower fuel utilization. Water crosses the membrane up to 14 times its production rate at the anode. Low fuel utilization and water imbalance suggest the importance of system designs with reactant recirculation and water recovery.

Comparative Study on Rosmarinic Acid Separation by Reactive Extraction with Amberlite LA-2 and D2EHPA. 1. Interfacial Reaction Mechanism and Influencing Factors

The mechanism of reactive extraction of rosmarinic acid with Amberlite LA-2 (secondary amine) and D2EHPA (organophosphoric acid) was analyzed for three solvents with different polarities (n-heptane, n-butyl acetate, dichloromethane), with or without 1-octanol. Thus, in the absence of 1-octanol, the stoichiometric ratio between the rosmarinic acid and Amberlite LA-2 was 1:1 for dichloromethane, 1:2 for butyl acetate, and 1:4 for n-heptane. In the presence of 1-octanol, the formation of aminic adducts is restricted, and the structures of the interfacial complexes reflect the following stoichiometries for the interfacial reaction between the solute and Amberlite LA-2: 1:1 for dichloromethane and butyl acetate and 1:2 for n-heptane. However, regardless of 1-octanol addition to the organic phase, the extraction of rosmarinic acid with D2EHPA occurred only through the formation of an interfacial compound containing one acid molecule and two molecules of extractant for all considered solvents. In the case of rea...

Potential smear layer interference with bonding of self-etching adhesives to dentin.

To evaluate the effect of smear-layer interposition on the bonding effectiveness of self-etching adhesives with different etching potential. Bur-cut dentin specimens were obtained from 25 human molars after preparation of the dentin surface with a medium-grit diamond bur (bur-cut). An additional 25 molars were fractured at the midcoronal dentin to create a smear-layer-free surface (smear-free dentin). The prepared teeth were assigned to 5 groups, according to the adhesive to be applied: a strong one-step self-etching adhesive (PLP, Adper Prompt L-Pop, 3M ESPE, pH = 0.8); two ultra-mild one-step self-etching adhesives (C3S, Clearfil Tri-S Bond, Kuraray, pH = 2.7; AEB, Adper Easy Bond, 3M ESPE; pH = 2.7 ); as the self-etching control, a mild two-step self-etching adhesive (CSE, Clearfil SE Bond, Kuraray, pH of primer = 1.9); and as the etch-and-rinse control, a three-step etch-and-rinse adhesive (OFL, Optibond FL, Kerr). After composite buildups were made, all specimens were stored in distilled water (24 h/37°C) prior to microtensile bond strength testing (µTBS). The failure mode was determined with a stereomicroscope at 50X magnification. Representative µTBS specimens were processed for analysis in a Feg-SEM. The Kruskal-Wallis test was performed to determine statistical differences (p < 0.05). Except for the strong one-step self-etching adhesive, all other self-etching adhesives (mild and ultramild) revealed a significantly lower bond strength to bur-cut dentin than to smear-free dentin. The etch-and-rinse adhesive presented the highest µTBS, which was not significantly different when bonded to bur-cut or smear-free dentin. Fracture analysis demonstrated a prevalence of adhesive failures for the self-etching adhesives, while OFL revealed more mixed failures. SEM revealed that smear debris remained part of the adhesive interfacial complex produced by the ultra-mild one-step self-etching adhesive C3S when applied on bur-cut dentin. Smear debris interferes with the interaction of mild and ultra-mild self-etching adhesives with dentin.

Follicular dermal papilla structures by organization of epithelial and mesenchymal cells in interfacial polyelectrolyte complex fibers

The hair follicle is a regenerating organ that produces a new hair shaft during each growth cycle. Development and cycling of the hair follicle is governed by interactions between the epithelial and mesenchymal components. Therefore, development of an engineered 3D hair follicle would be useful for studying these interactions to identify strategies for treatment of hair loss. We have developed a technique suitable for assembly of different cell types in close proximity in fibrous hydrogel scaffolds with resolutions of ∼50 μm. By assembly of dermal papilla (DP) and keratinocytes, structures similar to the native hair bulb arrangement are formed. Gene expression of these constructs showed up-regulation of molecules involved in epithelial–mesenchymal interactions of the hair follicle. Implantation of the follicular structures in SCID mice led to the formation of hair follicle-like structures, thus demonstrating their hair inductive ability. The transparency of the fiber matrix and the small dimensions of the follicular structures allowed the direct quantitation of DP cell proliferation by confocal microscopy, clearly illustrating the promoting or inhibitory effects of hair growth regulating agents. Collectively, our results suggested a promising application of these 3D engineered follicular structures for in vitro screening and testing of drugs for hair growth therapy.