Whey Protein Isolate Composites as Potential Scaffolds for Cultivated Meat.

Modern food technology has given rise to numerous alternative protein sources in response to a growing human population and the negative environmental impacts of current food systems. To aid in achieving global food security, one such form of alternative protein being investigated is cultivated meat, which applies the principles of mechanical and tissue engineering to produce animal proteins and meat products from animal cells. Herein, nonmodified and methacrylated whey protein formed hydrogels with methacrylated alginate as potential tissue engineering scaffolds for cultivated meat. Whey protein is a byproduct of dairy processing and was selected because it is an approved food additive and cytocompatible and has shown efficacy in other biomaterial applications. Whey protein and alginate scaffolds were formed via visible light cross-linking in aqueous solutions under ambient conditions. The characteristics of the precursor solution and the physical-mechanical properties of the scaffolds were quantified; while gelation occurred within the homo- and copolymer hydrogels, the integrity of the network was significantly altered with varying components. Qualitatively, the scaffolds exhibited a three-dimensional (3D) interconnected porous network. Whey protein isolate (WPI)-based scaffolds were noncytotoxic and supported in vitro myoblast adhesion and proliferation. The data presented support the hypothesis that the composition of the hydrogel plays a significant role in the scaffold's performance.

Dual-Crosslinked Alginate-Based Hydrogels with Tunable Mechanical Properties for Cultured Meat.

Cultured meat refers to the production of animal tissue by utilizing the same techniques as tissue engineering through cell culture. Various biomaterials have been designed to serve as in vitro supports for cell viability, growth, and migration. In this study, visible light and dual-crosslinked alginate hydrogels were designed to enable control of the physical and mechanical properties needed for the fabrication of cultured meat scaffolds. We hypothesized that a difference in hydrogel stiffness would influence cell behavior, indicating the efficacy of our processing methods to benefit the cultured meat field. Herein, we synthesized and created: (1) methacrylated alginate (AlgMA) to enable covalent crosslinking via visible light exposure, (2) Methacrylated alginate and arginyl-glycyl-aspartic acid RGD conjugates (AlgMA-RGD), using carbodiimide chemistries to provide cell-binding sites on the material, and (3) designer hydrogels incorporating different crosslinking techniques. The material and mechanical properties were evaluated to determine the structural integrity of the hydrogels, and in vitro cell assays were conducted to verify cytocompatibility and cell adhesion. Gelation, swell ratio, and weight loss calculations revealed longer gelation times for the AlgMA scaffolds and similar physical properties for all hydrogel groups. We showed that by adjusting the polymer concentration and the crosslinking methodology, the scaffold's mechanical properties can be controlled and optimized within physiological ranges. Incorporating dual crosslinking significantly increased the compressive moduli of the AlgMA hydrogels, compared to visible-light crosslinking alone. Moreover, the muscle satellite cells responded favorably to the AlgMA scaffolds, with clear differences in cell density when cultured on materials with significantly different mechanical properties. Our results indicate the usefulness of the dual-crosslinking alginate hydrogel system to support in vitro meat growth.

Effects of Blending Tobacco Lignin with HDPE on Thermal and Mechanical Properties.

Depletion of fossil fuels and the detrimental environmental impacts of synthetic plastics have prompted a global interest in bio-based polymers. Lignin is an abundant, unused, and low-value byproduct of pulping and biochemical operations that has the potential to decrease the need for plastics derived from petroleum. Melt blending is one of the easiest strategies for expanding the commercial applications of lignin. Concerns remain, however, regarding the negative effects of lignin on the final composite material's performance, and the increase in manufacturing costs. This study investigates the effects of blending lignin extracted from tobacco using a novel one-step processing technique on injection molding parameters, and the mechanical, physical, and thermal properties of high-density polyethylene (HDPE). By extruding HDPE pellets and lignin powder, varying blend concentrations (0, 5, 10, 15, and 30% wt.) were produced. Scanning electron microscopy (SEM) and optical microscopy were used to investigate the compatibility of the blend morphology. Results indicated that interfacial interactions were achieved as particles of tobacco lignin were well dispersed and uniformly distributed throughout HDPE. Intermolecular interactions between HDPE and lignin were also discovered through Fourier-transform infrared (FTIR) spectral analyses. The tensile test results showed that increase in lignin content up to 15% wt. had little effect on tensile strength, but at 30% wt., a 19% reduction was observed. With the addition of 5, 10, 15, and 30% wt. of lignin, the tensile modulus increased by 4%, 29%, 25%, and 8%, respectively. TGA results demonstrated that at 15% and 30% wt., tobacco lignin acted as a thermal stabilizer. The processability study revealed that tobacco lignin could be processed easily using injection molding without requiring significant changes to the process parameters. Overall, tobacco lignin showed great promise as a biodegradable HDPE filler.

Investigating the Effects of Tobacco Lignin on Polypropylene.

The utilization of eco-friendly materials, such as lignin, for higher value product applications became increasingly important as environmental concerns due to global warming increased. Melt blending is one of the easy ways to increase the usage of lignin in commercial applications. However, the degradation of the final product performance and increase in the production time and costs are of major concern. In the current work, the effects of blending lignin, extracted from tobacco plants, with polypropylene (PP) on the injection molding parameters, physical, thermal and mechanical properties are investigated. Blends of lignin (5, 15 and 30% by wt.) with PP were prepared using a Filabot single screw extruder. Results show that tensile strength decreases by 3.2%, 9.9% and 5.4% at 5 wt. %, 15 wt. %, and 30 wt. % of lignin addition, respectively. The tensile stiffness was almost unaffected by the addition of up to 15% lignin, but a 23% increase was observed at 30 wt. % loading. When compared to lignin processed via expensive processes, such as acetylation, tobacco lignin showed superior performance. The DSC results show unaffected crystallization and melting temperatures but a decrease in enthalpies and percentage of crystallinity. The SEM and optical micrographs of the coupon cross-sections show that the extrusion process has achieved a uniform distribution of lignin particles in the PP. Thermogravimetric analysis results show that tobacco lignin accelerates the onset decomposition temperature but does not influence the decomposition peak temperature. The increase in lignin content did not have a significant influence on the injection molding parameters, implying no additional processing costs for adding lignin to the PP. Overall, the performance of the tobacco lignin is comparable, if not better, than that of processed lignin reported in the literature.

Bio-inspired green light crosslinked alginate-heparin hydrogels support HUVEC tube formation.

Alginate is a polysaccharide which forms hydrogels via ionic and/or covalent crosslinking. The goal was to develop a material with suitable, physiologically relevant mechanical properties and biological impact for use in wound treatment. To determine if the novel material can initiate tube formation on its own, without the dependance on the addition of growth factors, heparin and/or arginyl-glycyl-aspartic acid (RGD) was covalently conjugated onto the alginate backbone. Herein, cell adhesion motifs and bioactive functional groups were incorporated covalently within alginate hydrogels to study the: 1) impact of crosslinked heparin on tubular network formation, 2) impact of RGD conjugation, and the 3) biological effect of vascular endothelial growth factor (VEGF) loading on cellular response. We investigated the structure-properties-function relationship and determined the viscoelastic and burst properties of the hydrogels most applicable for use as a healing cell and tissue adhesive material. Methacrylation of alginate and heparin hydroxyl groups respectively enabled free-radical covalent inter- and intra-molecular photo-crosslinking when exposed to visible green light in the presence of photo-initiators; the shear moduli indicate mechanical properties comparable to clinical standards. RGD was conjugated via carbodiimide chemistry at the alginate carboxyl groups. The adhesive and mechanical properties of alginate and alginate-heparin hydrogels were determined via burst pressure testing and rheology. Higher burst pressure and material failure at rupture imply physical tissue adhesion, advantageous for a tissue sealant healing material. After hydrogel formation, human umbilical vein endothelial cells (HUVECs) were seeded onto the alginate-based hydrogels; cytotoxicity, total protein content, and tubular network formation were assessed. Burst pressure results indicate that the cell responsive hydrogels adhere to collagen substrates and exhibit increased strength under high pressures. Furthermore, the results show that the green light crosslinked alginate-heparin maintained cell adhesion and promoted tubular formation.

The Property Characterization of α-Sialon/Ni Composites Synthesized by Spark Plasma Sintering.

This study investigates the effect of micron-sized nickel particle additions on the microstructural, thermal, and mechanical property changes of α-sialon ceramic composites. The α-sialon/Ni composites were synthesized with an increasing amount of Ni (10-40 wt.%) using the spark plasma sintering technique and nanosized alpha precursors at a relatively low synthesis temperature of 1500 °C with a holding time of 30 min in each case. The density of the samples increased with the increase in Ni content of up to 15 wt.% and, with the further increase in Ni content, it became almost constant with a slight decrease. Furthermore, thermal conductivity and thermal expansion properties of Ni-sialon composites improved slightly with the inclusion of 10 wt.% Ni. The addition of Ni to α-sialon matrix resulted in a decrease in the hardness of the composites from HV10 21.6 to HV10 16.3, however the presence of Ni as a softer interfacial phase resulted in a substantial increase in the fracture toughness of these composites. Fracture toughness was found to increase by approximately 91% at 40 wt.% Ni addition.

Long term outcomes for patients treated with half-fluence photodynamic therapy for chronic central serous chorioretinopathy: a case series.

A case series was used to evaluate the efficacy of half-fluence photodynamic therapy (PDT) for chronic central serous chorioretinopathy (CSCR). Patients were treated with standard-dose verteporfin and half-fluence PDT. Totally 13 eyes from 11 patients were included. The mean patient age was 52.0y. There was a mean reduction in central retinal thickness of 107.0 microns. Totally 7/13 eyes (53.8%) achieved resolution of subretinal fluid (SRF) on optical coherence tomography (OCT) scan after 1 treatment with PDT. Four eyes had further treatment with PDT; of these 1 eye achieved resolution of SRF. Seven of the 13 eyes (53.8%) achieved an improvement of more than 5 ETDRS letters. One patient experienced acute macula oedema 1d post PDT treatment. These results support the hypothesis that half-fluence PDT can have a positive effect in chronic CSCR for a gain in visual acuity and reduction in sub-retinal fluid. Acute macula oedema is a rare but potential adverse effect of half-fluence PDT.