Mechanical properties are one of the most important characteristics of biomaterials for many different applications, including biomedicine. Soft biomaterials, such as hydrogels, are difficult to characterize by conventional mechanical testing, because their mechanical properties are much lower than required by conventional testing machines. In this work, we aimed to systematically study the mechanical behavior of a model soft material, polyacrylamide hydrogels, under different loading modes: tension, torsion, compression, and indentation. This allowed us to develop a comprehensive approach to the mechanical testing of soft materials. To overcome excessive compression and slippage of the hydrogel samples when fixed in the grips during tension, additional 3D-printed grips were designed. Digital image correlation was used to determine the Poisson’s ratio of the hydrogels. The Young’s modulus values obtained from all types of mechanical tests analyzed were highly correlated. However, for hydrogels with a low crosslinker concentration, 1–2%, tension–compression asymmetry was observed. Moreover, the results of the mechanical tests were verified in indentation tests, including analytical estimation, and full-scale and numerical experiments. We also discuss the limits of using a two-parameter Mooney–Rivlin model for fitting hydrogel uniaxial tension deformation curves, which was unstable for the hydrogels with 4 and 9% crosslinker concentration. The implemented approach provided a comprehensive analysis of the mechanical behavior of biomaterials. The elastic moduli for all hydrogels studied were in the range from 20 to 160 kPa, which corresponds well to human soft tissues, making them a promising material for application as tissue-mimicking phantoms.

The paper proposed a new porous material for wound healing based on chitosan and C-phycocyanin (C-PC). In this work, C-PC was extracted from the cyanobacteria Arthrospira platensis biomass and purified through ammonium sulfate precipitation. The obtained C-PC with a purity index (PI) of 3.36 ± 0.24 was loaded into a chitosan sponge from aqueous solutions of various concentrations (250, 500, and 1000 mg/L). According to the FTIR study, chitosan did not form new bonds with C-PC, but acted as a carrier. The encapsulation efficiency value exceeded 90%, and the maximum loading capacity was 172.67 ± 0.47 mg/g. The release of C-PC from the polymer matrix into the saline medium was estimated, and it was found 50% of C-PC was released in the first hour and the maximum concentration was reached in 5–7 h after the sponge immersion. The PI of the released C-PC was 3.79 and 4.43 depending on the concentration of the initial solution.

3D-печать является одной из самых быстроразвивающихся современных технологий, оказывающих революционное влияние на изготовление изделий целевого назначения с заданными размерами, формами и свойствами. Полученные с использованием аддитивных технологий персонифицированные изделия востребованы в широком спектре областей применения: пищевой промышленности, косметологии, медицине. Одним из актуальных направлений, способствующих стремительному развитию технологий 3D-печати, является поиск новых материалов, пригодных для использования в качестве «чернил». В процессе развития аддитивных технологий появилась возможность использовать в качестве «чернил» концентрированные растворы полимеров или гидрогели с гибкими и организованными сетками. Гидрогелевые «чернила» для 3D-печати на основе полисахаридов представляют собой уникальный материал, способный связывать большое количество воды, позволяя напечатанным структурам имитировать мягкие ткани и обеспечивать непрерывное поступление питательных веществ. В данной работе рассмотрены особенности процесса температурно-индуцированного гелеобразования водных растворов йота-каррагинана и их влияния на получение гидрогелевых «чернил» для инжекционной 3D-печати.

The expanding application of three-dimensional matrices with complex surface topographies in regenerative medicine requires new methods to visualize and analyze the evolving elastic properties of tissue-engineered constructs (TECs) during maturation. In this study, scanning impulse acoustic microscopy (SIAM) was employed for the non-invasive investigation of non-woven matrices based on PLLA and its composites with chitosan. This technique was used to determine the speed of sound, integral attenuation, and spectral characteristics within the samples. The data obtained through acoustic microscopy were compared with the results from tensile testing, gel permeation chromatography, differential scanning calorimetry, scanning electron microscopy, and CCK-8 assays. The findings demonstrate that SIAM exhibits high sensitivity to alterations in the TEC’s composition, including the presence of functionalizing additives, embedded cells, and the subsequent processes of cell proliferation and extracellular matrix synthesis, as well as to changes in its geometric structure. Consequently, this methodology can be recommended as a powerful and non-destructive tool for the comprehensive monitoring of TECs throughout their in vitro maturation period.