Three-dimensional (3D) printing is a promising technology for solving a wide range of problems: regenerative medicine, tissue engineering, chemistry, etc. One of the potential applications of additive technologies is the production of highly porous structures with complex geometries, while printing is carried out using gel-like materials. However, the implementation of precise gel printing is a difficult task due to the high requirements for “ink”. In this paper, we propose the use of gel-like materials based on sodium alginate as “ink” for the implementation of the developed technology of extrusion-based 3D printing. Rheological studies were carried out for the developed alginate ink compositions. The optimal rheological properties are gel-like materials based on 2 wt% sodium alginate and 0.2 wt% calcium chloride. The 3D-printed structures with complex geometry were successfully dried using supercritical drying. The resulting aerogels have a high specific surface area (from 350 to 422 m²/g) and a high pore volume (from 3 to 3.78 cm³/g).

Currently, materials with specific, strictly defined functional properties are becoming increasingly important. A promising strategy for achieving these properties involves developing methods that facilitate the formation of hierarchical porous materials that combine micro-, meso-, and macropores in their structure. Macropores facilitate effective mass transfer of substances to the meso- and micropores, where further adsorption or reaction processes can occur. Aerogels represent a promising class of materials for implementing this approach. The formation of hierarchical porous structures in aerogels can be achieved using soft and hard templating methods or by foaming techniques. This paper presents a comprehensive study of three methods for forming hierarchical porous structures in alginate aerogels: (1) employing surfactants (Pluronic F-68), (2) using zein as a pore-forming component, and (3) foaming in a carbon dioxide medium. The results of micro-CT showed that each of the methods contributes to the formation of macropores within the structure of the resulting aerogels. Size distribution curves of the detected macropores were obtained, showing the presence of macropores ranging from 16 to 323 μm in size for samples obtained using surfactants, from 5 to 195 μm for samples obtained using zein, and from 20 μm to 3 mm for samples obtained by foaming in a carbon dioxide medium. The SEM images demonstrated the macro- and mesoporous fibrous structure of the obtained materials. The nitrogen porosimetry results indicated that samples obtained using surfactants and zein are characterized by a high specific surface area (592–673 m²/g), comparable to the specific surface area for an alginate-based aerogel obtained without the use of pore-forming components. However, the use of the developed methods for the formation of a hierarchical porous structure contributes to an increase in the specific mesopores volume (up to 17.7 cm³/g). The materials obtained by foaming in a carbon dioxide medium are characterized by lower specific surface areas (112–239 m²/g) and specific mesopores volumes (0.6–2.1 cm³/g). Thus, this paper presents a set of methods for forming hierarchical porous structures that can obtain delivery systems for active substances with a controlled release profile and highly efficient platforms for cell culturing.

3D printing represents a versatile approach for fabricating products with desired geometries. Of particular interest are extrusion methods of 3D printing that utilize “inks” consisting of viscous materials. The utilization of such “inks” enables the printing process to be carried out at low temperatures, with compositional variations, and facilitates the production of products with highly porous structures. Products printed using viscous materials hold great promise in the fields of medicine, pharmaceuticals, and the chemical industry. This paper outlines the stages involved in developing “inks” based on the sodium alginate biopolymer. Complex rheological studies were conducted on these “inks,” and two methods of 3D printing with viscous materials were implemented: direct gel printing and printing using a heterophase system. Two compositions of “inks” were devised, one based on pure sodium alginate and the other based on partially crosslinked sodium alginate. The viscosity of the sodium alginate-based “ink” ranged from 0.8 to 118.6 Pa s for polymer concentrations of 2–9 wt %. Materials with a sodium alginate concentration of 2 wt % exhibited the most pronounced thixotropic properties. It was demonstrated that sodium alginate-based “ink” can be effectively employed for 3D printing using a heterophase system, where the system serves as a supportive volume, preventing the printed product from spreading and enabling the formation of a 3D structure. In the case of partially crosslinked sodium alginate-based “ink” (2 wt %), the addition of a crosslinking agent resulted in a viscosity range of 1.8 to 1032.4 Pa·s for calcium chloride concentrations ranging from 0.05 to 0.3 wt %. This crosslinking agent allowed for an increase in viscosity, facilitating direct gel 3D printing without the need for a heterophase system. All the developed “inks” exhibited a pseudoplastic flow behavior, characterized by a decrease in viscosity with an increase in shear rate.

This paper presents modern methods of mathematical modeling, which are widely used in the development of new inhalation and intranasal drugs, including those necessary for the treatment of socially significant diseases, which include: tuberculosis, bronchial asthma, and mental and behavioral disorders. Based on the conducted studies, it was revealed that the methods of mathematical modeling used in the development of drugs are fragmented, and there is no single approach that would combine the existing methods. The results presented in the work should contribute to the development of a unified multiscale model as a new approach in mathematical modeling that contributes to the accelerated development and introduction to the market of new drugs with high bioavailability and the required therapeutic efficacy.

Currently, materials with specific, strictly defined functional properties are becoming increasingly important. A promising strategy for achieving these properties involves developing methods that facilitate the formation of hierarchical porous materials. Aerogels represent a promising class of materials for implementing this approach. The synthesis of aerogels based on biopolymers exhibiting a hierarchical porous structure—combining micropores, mesopores, and macropores—enables the development of active substance delivery systems with controlled release profiles and highly efficient platforms for cell cultivation. The formation of hierarchical porous structures in aerogels can be achieved using soft and hard templating methods or by foaming techniques. This paper presents a comprehensive study of three methods for forming hierarchical porous structures in alginate aerogels: (1) employing surfactants (Pluronic F-68), (2) using zein as a pore-forming component, and (3) foaming in a carbon dioxide environment. The results of computed X-ray microtomography (micro-CT), scanning electron microscopy (SEM) and nitrogen porosimetry are presented. For each method of forming hierarchical porous structures, we investigated the effects of various parameters on the structural characteristics of the resulting material: for method (1), the surfactant concentration (0.25-1.00 wt.%); for method (2) – alginate-to-zein ratio (20:1, 10:1, 5:1); and for method (3) – pressure (50 and 100 bar) and holding time (1 and 3 hours). The results of micro-CT showed that each of the methods contributes to the formation of macropores within the structure of the resulting aerogels. Size distribution curves of the detected macropores were obtained, showing the presence of macropores ranging from 16 to 323 micrometers in size for samples obtained using surfactants, from 5 to 195 micrometers for samples obtained using zein, and from 20 micrometers to 3 mm for samples obtained by foaming in a carbon dioxide medium. The SEM images demonstrated the macro- and mesoporous fibrous structure of the obtained materials. The nitrogen porosimetry results indicated that samples obtained using surfactants and zein are characterized by a high specific surface area (592-673 m2/g), comparable to the specific surface area for an alginate-based aerogel obtained without the use of pore-forming components. However, the use of the developed methods for the formation of a hierarchical porous structure contributes to an increase in the specific mesopores volume (up to 17.7 cm3/g). The materials obtained by foaming in a carbon dioxide medium are characterized by lower specific surface areas (112-239 m2/g) and specific mesopores volumes (0.6-2.1 cm3/g). Thus, this paper presents a set of methods for forming hierarchical porous structures, wherein macropores facilitate effective mass transfer of substances to meso- and micropores, where subsequent adsorption or reaction processes occur.

Direct ink writing (DIW) requires careful selection of ink composition with specific rheological properties, and it has limitations, such as the inability to create overhanging parts or branched geometries. This study presents an investigation into enhancing the 3D printing process through the use of a heterophase system, aiming to overcome these limitations. A modification was carried out in the 3D printer construction, involving adjustments to the structural elements responsible for the extrusion device’s movement. Additionally, a method for obtaining a heterophase system based on gelatin microparticles was developed to enable the 3D printing process with the upgraded printer. The structure and rheological properties of the heterophase system, varying in gelatin concentration, were thoroughly examined. The material’s viscosity ranged from 5.4 to 32.8 kPa·s, exhibiting thixotropic properties, pseudoplastic behavior, and long-term stability at 20 °C. The developed 3D printing technology was successfully implemented using a heterophase system based on different gelatin concentrations. The highest product quality was achieved with a heterophase system consisting of 4.5 wt.% gelatin, which exhibited a viscosity of 22.4 kPa·s, enabling the production of products without spreading or compromising geometrical integrity.