The fibrous porous structure of polymers can mimic the extracellular matrix of the native tissue, therefore such polymers have a good potential for use in regenerative medicine. Organs and tissues within the body exhibit different mechanical properties depending on their functionality, thus artificial scaffolds should have mechanical behaviors similar to the extracellular matrix in conditions like living organisms, primarily in aqueous media. Several methods have been investigated in aquatic environments, including noninvasive techniques based on ultrasonic focused beams for biological objectives. In this study we explored the tensile behavior of poly(L-lactide) nonwoven polymer scaffolds using high-frequency ultrasound microscopy combined with a horizontal testing machine, which provided a visualization of the reorganization and transformation of the dynamic volume microstructure. The mechanisms of unwinding, elongation, orientation, and deformation of polymer fibers under uniaxial tension were revealed. We observed an association between the lined plastic deformation from 100 to 400% and the formation of multiple necks in the fibers, which caused stress relaxation and significant rarefaction of the fibrous microstructure. It was shown that both peaks on the stress–strain curve corresponded to the microstructure of aligned fibers in terms of initial diameter and thinning fibers. We discuss the possible influence of these microstructure transformations on cell behavior.

High-strength composite hydrogels based on collagen or chitosan–genipin were obtained via mixing using highly porous polylactide (PLA) microparticles with diameters of 50–75 µm and porosity values of over 98%. The elastic modulus of hydrogels depended on the filler concentration. The modulus increased from 80 kPa to 400–600 kPa at a concentration of porous particles of 12–15 wt.% and up to 1.8 MPa at a filling of 20–25 wt.% for collagen hydrogels. The elastic modulus of the chitosan–genipin hydrogel increases from 75 kPa to 900 kPa at a fraction of particles of 20 wt.%. These elastic modulus values cover a range of strength properties from connective tissue to cartilage tissue. It is important to note that the increase in strength in this case is accompanied by a decrease in the density of the material, that is, an increase in porosity. PLA particles were loaded with C-phycocyanin and showed an advanced release profile up to 48 h. Thus, composite hydrogels mimic the structure, biomechanics and release of biomolecules in the tissues of a living organism.

In this study we verified the method of impulse acoustic microscopy as a tool for scaffold evaluation in tissue engineering investigation. Cellulose diacetate (CDA) non-woven 3D scaffold was used as a model object. Scanning electron microscopy and optical microscopy were used as reference methods in order to realize feasibility of acoustic microscopy method in a regenerative medicine field. Direct comparison of the different methods was carried out.

Russian experience in the development of high-resolution ultrasound technologies for bioimaging is considered. Two types of ultrasound biomicroscopy (UBM) systems for the in vivo imaging of skin are...