Creating gradients of amyloid fibrils from the liquid-liquid interface.

We report a method to deposit amyloid fibrils on a substrate creating gradients in orientation and coverage on demand. For this purpose, we adapt a colloidal self-assembly method at liquid-liquid interfaces to deposit amyloid fibrils on a substrate from the water-hexane interface, while simultaneously compressing it. The amyloid fibril layers orient perpendicularly to the compression, ranging from isotropic to nematic distributions. We furthermore observe reproducible transitions from a monolayer to a bilayer and from a bilayer to multilayers with increasing surface pressures. The creation of each new layer is accompanied by a systematic drop in the structural order of the system, which is however regained upon further compression. This method shows great potential for overcoming the thin-film engineering challenges associated with the manipulation of sticky amyloid fibrils, and allows their ex situ visualisation under compression at the fluid-fluid interface, a situation relevant to understand the propagation of amyloid-related diseases, their functional role in biological systems, and their potential for technological applications.

Interfacial Activity and Contact Angle of Homogeneous, Functionalized, and Janus Nanoparticles at the Water/Decane Interface.

Surface heterogeneity affects the behavior of nanoparticles at liquid interfaces. To gain a deeper understanding on the details of these phenomena, we have measured the interfacial activity and contact angle at water/decane interfaces for three different types of nanoparticles: homogeneous poly(methyl methacrylate) (PMMA), silica functionalized with a capping ligand containing a methacrylate terminal group, and Ag-based Janus colloids with two capping ligands of different hydrophobicity. The interfacial activity was analyzed by pendant drop tensiometry, and the contact angle was measured directly by freeze-fracture shadow-casting cryo-scanning electron microscopy. The silver Janus nanoparticles presented the highest interfacial activity, compared to the silica nanoparticles and the homogeneous PMMA nanoparticles. Additionally, increasing the bulk concentration of the PMMA and silica nanoparticles up to 100-fold compared to the Janus nanoparticles led to silica particles forming fractal-like structures at the interface, contrary to the PMMA particles that did not show any spontaneous adsorption.

Analysis of Tissue Repair of a New Cement Based on Calcium and Strontium Aluminates: A Triple-Blinded, Randomized, Controlled Trial in an Animal Model.

OBJECTIVE: The focus of this triple-blind randomized study was to evaluate the biocompatibility of a new root canal filling sealer (RCFS) based on tristrontium aluminate and dodecacalcium hepta-aluminate in living tissue. MATERIAL AND METHODS: Forty-five Wistar rats (Rattus norvegicus) were divided into three groups: control (polyethylene), sealer (Bio-C Sealer, Londrina, PR, Brazil), and experimental (tristrontium aluminate and dodecacalcium hepta-aluminate). The tissues were analyzed under an optical microscope to assess different cellular events at different time intervals (7, 15, and 30 days). STATISTICAL ANALYSIS: Data were analyzed using the Kruskal-Wallis and Dunn (p < 0.05) tests. RESULTS: In the initial period, a moderate inflammatory infiltrate was observed, similar between the endodontic cements groups (p = 0.725). The intensity of the infiltrate decreased with time, with no significant difference among the groups (p > 0.05). The number of young fibroblasts was elevated in all groups evaluated at 7 days. The experimental group showed the highest number of cells at all time intervals, but the difference with the sealer group at 7 (p = 0.001) and 15 days (p = 0.002) and the control group at 30 days was not significant (p = 0.001). Regarding tissue repair events, the amount of collagen fibers increased over the experimental intervals, with no significant difference between the sealer and control groups (p > 0.05). CONCLUSION: The experimental RCFS based on calcium and strontium aluminates proved to be biocompatible for use in close contact with periapical tissue, inducing a low inflammatory reaction and favoring rapid tissue repair.

Salivary and serum beta2-microglobulin and gamma-glutamyl-transferase in patients with primary Sjögren syndrome and Sjögren syndrome secondary to systemic lupus erythematosus.

BACKGROUND: Sialochemistry has been proposed as a simple and useful tool for the diagnosis of Sjögren syndrome (SS). Although many changes have been detected in several constituents of saliva from patients with SS, none are individually sensitive or specific enough for diagnosing SS. The aim of this study was to assess the value of the combined determination of beta2-microglobulin (beta2m) and gamma-glutamyl-transferase (GGT) activity in serum and saliva as a diagnostic instrument for differentiating primary and secondary [to systemic lupus erythematosus (SLE)] SS patients from normal subjects. METHODS: Nineteen primary SS (pSS) patients, 15 patients with SS secondary to SLE, and 25 SLE patients without SS were studied. Thirty healthy subjects were included in the study as control group. RESULTS: By means of a mathematical model, (a) 84.1%, (b) 85.7%, and (c) 87.0% of patients were correctly classified as SS or normal when (a) salivary beta2m and GGT values, (b) serum beta2m and salivary GGT values, and (c) salivary beta2m and GGT along with serum beta2m values, respectively, were considered. To differentiate between pSS and sSS by means of the mathematical model, the combination of serum beta2m and salivary GGT values achieved that 81.8% of the patients were correctly classified. CONCLUSION: Since sialochemistry is an easy, safe and reliable test, the combined determination of beta2m and GGT in saliva and serum was useful for differentiating SS patients from normal subjects, but not excessively good for differentiating pSS from sSS patients.