Strategies for the Biofunctionalization of Straining Flow Spinning Regenerated Bombyx mori Fibers.

High-performance regenerated silkworm (Bombyx mori) silk fibers can be produced efficiently through the straining flow spinning (SFS) technique. In addition to an enhanced biocompatibility that results from the removal of contaminants during the processing of the material, regenerated silk fibers may be functionalized conveniently by using a range of different strategies. In this work, the possibility of implementing various functionalization techniques is explored, including the production of fluorescent fibers that may be tracked when implanted, the combination of the fibers with enzymes to yield fibers with catalytic properties, and the functionalization of the fibers with cell-adhesion motifs to modulate the adherence of different cell lineages to the material. When considered globally, all these techniques are a strong indication not only of the high versatility offered by the functionalization of regenerated fibers in terms of the different chemistries that can be employed, but also on the wide range of applications that can be covered with these functionalized fibers.

Neck circumference in Latin America and the Caribbean: A systematic review and meta-analysis.

Background: High neck circumference (NC) is associated with high burden diseases in Latin American and the Caribbean (LAC). NC complements established anthropometric measurements for early identification of cardio-metabolic and other illnesses. However, evidence about NC has not been systematically studied in LAC. We aimed to estimate the mean NC and the prevalence of high NC in LAC. Methods: We conducted a systematic review in MEDLINE, Embase, Global Health and LILACS. Search results were screened and studied by two reviewers independently. To assess risk of bias of individual studies, we used the Hoy et al. scale and the Newcastle-Ottawa scale. We conducted a random-effects meta-analysis. Results: In total, 182 abstracts were screened, 96 manuscripts were reviewed and 85 studies (n= 51,978) were summarized. From all the summarized studies, 14 were conducted in a sample of the general population, 23 were conducted with captive populations and 49 studies were conducted with patients. The pooled mean NC in the general population was 35.69 cm (95% IC: 34.85cm-36.53cm; I²: 99.6%). In our patient populations, the pooled mean NC in the obesity group was 42.56cm (95% CI 41.70cm-43.42cm; I²: 92.40%). Across all studied populations, there were several definitions of high NC; thus, prevalence estimates were not comparable. The prevalence of high NC ranged between 37.00% and 57.69% in the general population. The methodology to measure NC was not consistently reported. Conclusions: Mean NC in LAC appears to be in the range of estimates from other world regions. Inconsistent methods and definitions hamper cross-country comparisons and time trend analyses. There is a need for consistent and comparable definitions of NC so that it can be incorporated as a standard anthropometric indicator in surveys and epidemiological studies.

Structure-Function Relationship of Artificial Spider Silk Fibers Produced by Straining Flow Spinning.

The production of large quantities of artificial spider silk fibers that match the mechanical properties of the native material has turned out to be challenging. Recent advancements in the field make biomimetic spinning approaches an attractive way forward since they allow the spider silk proteins to assemble into the secondary, tertiary, and quaternary structures that are characteristic of the native silk fiber. Straining flow spinning (SFS) is a newly developed and versatile method that allows production under a wide range of processing conditions. Here, we use a recombinant spider silk protein that shows unprecedented water solubility and that is capable of native-like assembly, and we spin it into fibers by the SFS technique. We show that fibers may be spun using different hydrodynamical and chemical conditions and conclude that these spinning conditions affect fiber mechanics. In particular, it was found that the addition of acetonitrile and polyethylene glycol to the collection bath results in fibers with increased ß-sheet content and improved mechanical properties.

Enhanced Biological Response of AVS-Functionalized Ti-6Al-4V Alloy through Covalent Immobilization of Collagen.

This study presents the development of an efficient procedure for covalently immobilizing collagen molecules on AVS-functionalized Ti-6Al-4V samples, and the assessment of the survival and proliferation of cells cultured on these substrates. Activated Vapor Silanization (AVS) is a versatile functionalization technique that allows obtaining a high density of active amine groups on the surface. A procedure is presented to covalently bind collagen to the functional layer using EDC/NHS as cross-linker. The covalently bound collagen proteins are characterized by fluorescence microscopy and atomic force microscopy and their stability is tested. The effect of the cross-linker concentration on the process is assessed. The concentration of the cross-linker is optimized and a reliable cleaning protocol is developed for the removal of the excess of carbodiimide from the samples. The results demonstrate that the covalent immobilization of collagen type I on Ti-6Al-4V substrates, using the optimized protocol, increases the number of viable cells present on the material. Consequently, AVS in combination with the carbodiimide chemistry appears as a robust method for the immobilization of proteins and, for the first time, it is shown that it can be used to enhance the biological response to the material.

Straining Flow Spinning of Artificial Silk Fibers: A Review.

This work summarizes the main principles and some of the most significant results of straining flow spinning (SFS), a technology developed originally by the authors of this work. The principles on which the technology is based, inspired by the natural spinning system of silkworms and spiders, are presented, as well as some of the main achievements of the technique. Among these achievements, spinning under environmentally friendly conditions, obtaining high-performance fibers, and imparting the fibers with emerging properties such as supercontraction are discussed. Consequently, SFS appears as an efficient process that may represent one of the first realizations of a biomimetic technology with a significant impact at the production level.