Silk fibroin is a promising biomaterial for tissue engineering due to its valuable mechanical and biological properties. However, being a natural product and a protein, it lacks the processability and uniform quality of an advanced synthetic material. Here we propose a way to overcome this contradiction using novel fibroin photocrosslinkable derivative (FBMA). FBMA was synthesized by methacrylation of native fibroin nucleophilic side groups. It was dissolved in either formic acid (FA) or hexafluoroisopropanol (HFIP), and the obtained solutions were photocrosslinked into hydrogel scaffolds of various structural forms including films, micropatterns, pads and macroporous sponges. UV-exposition of dry FBMA films through a photomask created complex microscaled patterns of the polymer. The nature of the solvent affected the properties of resulting hydrogels. When HFIP was used as the solvent, the resulting hydrogels had a storage modulus ∼4 times higher than that of hydrogels fabricated using FA and ∼20 times higher compared to the reference hydrogel obtained from pristine fibroin. Both FBMA-based hydrogels were biocompatible and supported fibroblast adhesion and growth in vitro. Cells cultivated on FBMA scaffolds produced with HFIP exhibited more spread phenotype at 4 and 24 h of cultivation, consistent with increased stiffness of the hydrogel. Hence, FBMA is an attractive material for fabrication of micropatterned scaffolds of centimeterscale size with minutely tunable physico-chemical properties via convenient and reproducible technological processes, applicable for rapid prototyping.

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The aim of the investigation was to study the biological and mechanical properties of silk fibroin films and composite silk fibroin films containing 30% collagen by weight.Materials and Methods. All films were prepared by casting method using water and formic acid as solvents. Scanning electron microscopy and atomic force microscopy were applied. Human hepatoblastoma cell line Hep-g 2 was used to test film compatibility.Results. We studied surface roughness degree of the obtained films. Water-based films were found to have permeability for low molecular weight substances. Tensile strength and elasticity indices were measured for all types of films. Collagen added to film composition was revealed to have no significant effect on tensile strength, though it increased film elasticity. We studied the degradation of films. Collagen was shown to have no significant impact on film degradation rate both in phosphate-buffer saline and oxidizing media. We demonstrated with an example of cell line Hep-g 2 that water-based films exhibit higher proliferative activity.Conclusion. Silk fibroin water solution has the best properties to develop films for tissue engineering.

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Tuberculosis is one of the most threatening infectious diseases and represents an important and significant reason for mortality in high-burden regions. The only licensed vaccine, BCG, is hardly capable of establishing long-term tuberculosis protection and is highly variable in its effectiveness. Even after 100 years of BCG use and research, we still cannot unequivocally answer the question of which immune correlates of protection are crucial to prevent Mycobacterium tuberculosis (Mtb) infection or the progression of the disease. The development of a new vaccine against tuberculosis arises a nontrivial scientific challenge caused by several specific features of the intracellular lifestyle of Mtb and the ability of the pathogen to manipulate host immunity. The purpose of this review is to discuss promising strategies and the possibilities of creating a new vaccine that could replace BCG and provide greater protection. The considered approaches include supplementing mycobacterial strains with immunodominant antigens and genetic engineering aimed at altering the interaction between the bacterium and the host cell, such as the exit from the phagosome. Improved new vaccine strains based on BCG and Mtb undergoing clinical evaluation are also overviewed.

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