3D bioprinting processes show great potential in the context of repair, regeneration, and substituting damaged tissues. Incorporating biomaterials of natural origin into the structure of sodium alginate through adhesive peptides and cellular ligands effectively improves its bioactivity. Despite the advantages and common use of gelatin-based hydrogel materials, their application carries limitations. The possibility of replacing gelatin with collagen during the production of bioinks is becoming promising. Marine organisms are safe, attractive sources from the point of view of ethical restrictions, as well as abundant due to the amount of waste from collagen sources. This work focuses on analyzing the effect of different concentrations of 50-50 mixture of cold and warm water fish collagen in polymer solutions on the physicochemical and mechanical properties of the developed materials, emphasizing their significant impact on cell proliferation in bioprinted constructs. The obtained results demonstrate that increasing the concentration of fish collagen increases the system’s viscosity; at the same time, in the case of the final hydrogel materials, a higher swelling degree and improved mechanical properties can be obtained. Furthermore, the use of 1.5% (w/v) fish collagen in sodium alginate-based bioinks (2A1.5ColF) promotes proliferation and the organization of cells into extensive cellular networks, leading to the formation of tissue structures.

This study presents the design and validation of a modular, multi-head 3D bioprinter developed for the fabrication of single- and multilayer tubular constructs. The system integrates two extrusion heads for hydrogels or cell-laden bioinks with a direct-feed head for thermoplastic polymers, thereby enabling materials with markedly different processing requirements to be deposited within a single manufacturing platform.,The hydrogel-printing modules provide independent material delivery and temperature control, allowing different hydrogel formulations or cell-laden bioinks to be processed. The thermoplastic module produces a mechanically supportive outer framework intended to improve the handling and structural stability of the hydrogel component. Tubular constructs were fabricated on a rotating, multi-diameter mandrel using a PCL/PLGA thermoplastic blend and an alginate-gelatin bioink containing NIH/3T3 mouse fibroblasts.,Device performance was evaluated through chamber decontamination tests, fabrication of multimaterial tubular constructs, extract-based cytotoxicity testing of the thermoplastic material, and Live/Dead assessment of cells encapsulated in the hydrogel phase. No microbial growth was detected in the tested media after chamber treatment. Cell viability exceeded the 70% cytotoxicity threshold for both filament and printed thermoplastic extracts, while fibroblast viability in the bioprinted hydrogel was 90.2 ± 1.3% immediately after printing and remained 83.7 ± 2.1% after 9 days. These findings demonstrate the feasibility of integrating thermoplastic printing and extrusion bioprinting for the manufacture of tubular tissue-engineering constructs.