Over the last few years, biopolymers have attracted great interest in tissue engineering and regenerative medicine due to the great diversity of their chemical, mechanical, and physical properties for the fabrication of 3D scaffolds. This review is devoted to recent advances in synthetic and natural polymeric 3D scaffolds for bone tissue engineering (BTE) and regenerative therapies. The review comprehensively discusses the implications of biological macromolecules, structure, and composition of polymeric scaffolds used in BTE. Various approaches to fabricating 3D BTE scaffolds are discussed, including solvent casting and particle leaching, freeze-drying, thermally induced phase separation, gas foaming, electrospinning, and sol–gel techniques. Rapid prototyping technologies such as stereolithography, fused deposition modeling, selective laser sintering, and 3D bioprinting are also covered. The immunomodulatory roles of polymeric scaffolds utilized for BTE applications are discussed. In addition, the features and challenges of 3D polymer scaffolds fabricated using advanced additive manufacturing technologies (rapid prototyping) are addressed and compared to conventional subtractive manufacturing techniques. Finally, the challenges of applying scaffold-based BTE treatments in practice are discussed in-depth.

Chitosan is one of the most abundant biopolymers in nature with high economic value due to its biocompatibility, biodegradability, lack of toxicity, and antifungal activity. In this study, chitosan was extracted from three different sources: Blaps lethifera (CSB), Pimelia fernandezlopezi (CSP), and Musca domestica (CSM). The ash content (AC), moisture content (MC), fat binding capacity (FBC), water binding capacity (WBC), and deacetylation degree (DD) were determined for the prepared chitosans. The effect of the DD of chitosan on the antibacterial activity of gram (positive/negative) bacteria and the azo dyes (methylene blue, MB) removal from wastewater was also investigated. Chitosan extracts showed good antibacterial activity against Listeria innocua, Bacillus subtiliis, Staphylococcus aureus, Salmonella typhimurium, and Pseudomonas aeruginosa. The MB dye removal of CSB-chitosan, CSP-chitosan, and CSM-chitosan reached 37%, 87%, and 26%, respectively, at a contact time of 2 h, a low initial dye concentration MB of 13 ppm, a solution temperature of 25 °C, and a pH = 7. Graphical Abstract

Silver nanoparticles (Ag NPs) play a significant role in modern medicine, with their size, shape, and surface chemistry strongly influencing their biological performance. Smaller nanoparticles (1-100 nm) can penetrate cells more easily, while different shapes such as spheres, rods, cubes, triangles, wires, and stars impact their antimicrobial activity and drug delivery efficiency. This review highlights the importance of precise control over these properties during synthesis to optimize their therapeutic potential. Green synthesis methods, including plant-based and microbial approaches, are presented as safer, more cost-effective, and environmentally friendly alternatives to conventional chemical processes. The review also discusses surface functionalization strategies such as biodegradable coatings, targeting ligands, and hybrid structures that enhance nanoparticle stability, reduce toxicity, and enable selective delivery to sites like tumors or infected tissues. As highlighted in the review, Ag NPs hold great promise in antimicrobial therapy, targeted drug delivery, diagnostics, tissue engineering, stem cell support, and cancer treatment. Emerging research also indicates potential benefits in modulating inflammation and oxidative stress in neurological and cardiovascular disorders. Despite these advances, key challenges remain, including low synthesis yields, poor reproducibility, scale-up difficulties, potential toxicity, uncertain biological mechanisms, and a lack of regulatory clarity. The review indicates the urgent need for improved synthesis control and rigorous safety evaluations to support the clinical translation of Ag NP-based technologies.