Lighting the Path: Light Delivery Strategies to Activate Photoresponsive Biomaterials In Vivo

Photoresponsive biomaterials are experiencing a transition from in vitro models to in vivo demonstrations that point toward clinical translation. Dynamic hydrogels for cell encapsulation, light-responsive carriers for controlled drug delivery, and nanomaterials containing photosensitizers for photodynamic therapy are relevant examples. Nonetheless, the step to the clinic largely depends on their combination with technologies to bring light into the body. This review highlights the challenge of photoactivation in vivo, and presents strategies for light management that can be adopted for this purpose. The authors’ focus is on technologies that are materials-driven, particularly upconversion nanoparticles that assist in “direct path” light delivery through tissue, and optical waveguides that “clear the path” between external light source and in vivo target. The authors’ intention is to assist the photoresponsive biomaterials community transition toward medical technologies by presenting light delivery concepts that can be integrated with the photoresponsive targets. The authors also aim to stimulate further innovation in materials-based light delivery platforms by highlighting needs and opportunities for in vivo photoactivation of biomaterials.     

BMP9-Induced Survival Effect in Liver Tumor Cells Requires p38MAPK Activation

The study of bone morphogenetic proteins (BMPs) role in tumorigenic processes, and specifically in the liver, has gathered importance in the last few years. Previous studies have shown that BMP9 is overexpressed in about 40% of hepatocellular carcinoma (HCC) patients. In vitro data have also shown evidence that BMP9 has a pro-tumorigenic action, not only by inducing epithelial to mesenchymal transition (EMT) and migration, but also by promoting proliferation and survival in liver cancer cells. However, the precise mechanisms driving these effects have not yet been established. In the present work, we deepened our studies into the intracellular mechanisms implicated in the BMP9 proliferative and pro-survival effect on liver tumor cells. In HepG2 cells, BMP9 induces both Smad and non-Smad signaling cascades, specifically PI3K/AKT and p38MAPK. However, only the p38MAPK pathway contributes to the BMP9 growth-promoting effect on these cells. Using genetic and pharmacological approaches, we demonstrate that p38MAPK activation, although dispensable for the BMP9 proliferative activity, is required for the BMP9 protective effect on serum withdrawal-induced apoptosis. These findings contribute to a better understanding of the signaling pathways involved in the BMP9 pro-tumorigenic role in liver tumor cells.     

Usage,content and citation in open access publication: any interaction effects?

Scientometrics - This study aims to validate an empirical model, at document level, that explains the interaction among content, usage, and citation within open access publications. The...     

Effect of laboratory foamer on asphalt foaming characteristics and foamed mixture properties

In the United States, mechanical foaming is the most popular method for producing warm mix asphalt, which is the latest technology implemented to reduce the production temperature and/or enhance the compactability of asphalt mixtures. Three commonly used commercially available laboratory foamers to produce asphalt foams include the Wirtgen WLB 10S (Wirtgen foamer), the InstroTek Accufoamer (InstroTek foamer) and the Pavement Technology Inc. Foamer (PTI foamer). Though these foamers have been widely used in research studies and construction practice, it is still unknown whether they produce asphalt foams with the same quality and quantity. In this study, asphalt foaming characteristics produced by these three laboratory foamers were measured using a non-contact test set-up consisting of a laser device and a digital camera, and compared in terms of instantaneous volume expansion, foam stability and surface area evolution of foam bubbles. Additionally, the workability, coatability and mechanical performance of foamed mixtures prepared using these same laboratory foamers were compared against the conventional hot mix asphalt (HMA). Test results indicated that foamed asphalts produced by the Wirtgen foamer had the largest volume expansion and greatest foam stability, followed by those produced by the InstroTek foamer and the PTI foamer. The optimum foaming water content (W_opt) was determined for each laboratory foamer based on the workability and coatability results of the corresponding foamed mixtures. In addition, the performance evaluation of the foamed mixtures produced at W_opt values indicated equivalent mixture stiffness but greater moisture susceptibility as compared to the conventional HMA.     

Influence of Field Effects on the Performance of InGaAs-Based Terahertz Radiation Detectors

A detailed electrical characterization of high-performance bow-tie InGaAs-based terahertz detectors is presented along with simulation results. The local surface potential and tunnelling current were scanned over the surfaces of the detectors by means of Kelvin probe force microscopy (KPFM) and scanning tunnelling microscopy (STM), which also enabled the determination of the Fermi level. Current-voltage curves were measured and modelled using the Synopsys Sentaurus TCAD package to gain deeper insight into the processes involved in detector operation. In addition, we performed finite-difference time-domain (FDTD) simulations to reveal features related to changes in the electric field due to the metal detector contacts. The investigation revealed that field-effect-induced conductivity modulation is a possible mechanism contributing to the high sensitivity of the studied detectors.     

The effects of extrusion conditions and the addition of volatile compounds and flavour enhancers to corn grits on the retention of the volatile compounds and texture of the extrudates

Corn grits that were supplemented with isovaleraldehyde, ethyl butyrate, butyric acid and flavour enhancers were extruded under different processing conditions. Volatile compounds retained in the extrudates were isolated by dynamic headspace and analysed using gas chromatography–mass spectrometry. The expansion ratio, density and cut force to break down the extrudates were evaluated and aroma intensity was assessed using a multisample difference test. Butyric acid showed the greatest retention (96.4%), regardless of the extrusion conditions. All compounds were better retained when samples were extruded at 20% feed moisture and 90 °C processing temperature (2.9–81.0%), conditions that also resulted in greater aromatic intensity (moderate to moderate‐strong intensity). The addition of volatile compounds reduced the expansion ratio and cut force, whereas the addition of flavour enhancers increased the expansion ratio but reduced ethyl butyrate and butyric acid retention.     

Esterification of Free Fatty Acids Using Layered Carboxylates and Hydroxide Salts as Catalysts

Layered lanthanum and copper(II) laurates were tested as catalysts for methanolic esterification of lauric acid (C₁₂). Factorial design evidenced a positive effect of reaction temperature and amount of catalyst on ester conversion, while the acid:alcohol molar ratio (MR) had a negative effect. With lanthanum laurate, 90.5% conversion was reached at 140???C with 10% catalyst and MR of 6:1. Although the highest conversion with copper(II) laurate converted 81.5% under the same conditions, results were better with a lower amount of catalyst (78% ester at 140???C with 2% catalyst and MR of 6:1). A calcium hydroxide succinate was also investigated showing better catalytic performance than the well-known CaO, under mild reaction conditions (120???C with 1% catalyst and MR of 3:1). Although layered carboxylates can be successively reused, the layered calcium hydroxide salt transformed into inactive CaCO₃ in the second reuse reaction.