Advances in bone tissue engineering depend on biomaterials that can promote osteogenic differentiation and matrix mineralization for functional bone regeneration. Gellan gum (GG), a naturally derived polysaccharide, which is biocompatible, has tunable gelation, and has potential bioactivity, is considered an ideal candidate for composite scaffolds. This study evaluates the osteogenic potential of two GG variants, low acyl gellan gum (LA-GAGR) and Mini-GAGR, and compares their effects with other polysaccharides, hyaluronic acid (HA), welan gum (WG), and dextran. MC3T3-E1 mouse pre-osteoblast cells were cultured with each polysaccharide in both liquid and hydrogel formulations over 3, 7, and 14 days. Osteogenic responses were assessed through Alizarin Red Staining (ARS) for calcium deposition, alkaline phosphatase (ALP) staining, and gene expression of key osteogenic markers. LA-GAGR (500 kDa) and Mini-GAGR (760 Da) in their hydrogel form showed higher calcium deposition, and upregulation of osteogenesis-associated genes (RUNX2, SP7) and extracellular matrix (ECM)–associated genes (OCN, OPN, and COL1), when compared with other polysaccharides. Notably, Mini-GAGR showed higher effects than LA-GAGR on osteogenic markers, matrix-associated gene expression, while LA-GAGR, with its higher molecular weight, showed higher ALP staining intensity. Overall, these results suggest that LA-GAGR and Mini-GAGR exhibit osteogenic potential under the tested in vitro conditions, supporting their further investigation as polysaccharide-based materials for bone tissue engineering applications.

The development of modern osteoplastic materials with controlled immunomodulatory properties represents a critical objective in bone tissue engineering. Octacalcium phosphate (OCP) serves as a promising precursor to bone apatite; however, its clinical application is limited by inconsistent biological response for recipients with similar nosology. Ionic doping presents a prospective approach for enhancing the functional characteristics of calcium phosphates. This study is dedicated to the synthesis and in vitro investigation of the immunomodulatory effects of low-temperature OCP co-doped with Sr²⁺/Mg²⁺ and Sr²⁺/Ba²⁺. The developed materials were characterized using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The incorporation of strontium during OCP synthesis was shown to destabilize the crystal lattice and reduce crystallite size. In vitro studies utilizing monocyte-like (THP-1 ATRA) and macrophage-like (THP-1 PMA) cell models demonstrated that the doped OCP materials did not induce cytotoxic effects and effectively modulated the functional activity of immune cells. Specifically, in monocyte-like cells, both OCP materials enhanced phagocytic activity and significantly increased the secretion of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6). In macrophage-like cells, the materials reduced phagocytic activity and exerted dual ion-dependent effects on reactive oxygen species (ROS) production. Furthermore, they stimulated cytokine secretion predominantly under non-inflammatory conditions. Notably, OCP_Sr20_Mg1 induced a comparatively milder proinflammatory response compared to OCP_Sr20_Ba1, specifically reducing ROS formation and cytokine secretion by monocyte-like and macrophage-like cells under standard conditions. These results suggest that Sr/Mg co-doping may provide a more balanced immunomodulatory profile favorable for osteoplastic applications. The findings indicate that the immunomodulatory effect is likely mediated through direct particle-cell interactions influencing intracellular processes such as phagocytosis and lysosomal activity, rather than being solely attributable to soluble ion release.

Photodynamic therapy (PDT) has shown significant advantages in tumor treatment due to its minimally invasive nature, low toxicity, and high selectivity. This article systematically reviews the research progress of organic photosensitizers (PSs) used in tumor PDT in recent years, and classifies them into six major categories based on chemical structure: porphyrins, chlorins, phthalocyanines, fused quinones, phenothiazines, and BODIPYs. It focuses on the innovative applications of various PSs in molecular design optimization, regulation of photophysical properties, nanonization strategies, and multimodal synergistic therapy. Strategies such as targeted delivery, microenvironment modulation (e.g., hypoxia alleviation, GSH depletion, pH responsiveness), and Type I photodynamic mechanisms have significantly enhanced PDT efficacy. Combined with two-photon excitation, NIR-II window absorption, and imaging guidance, the tissue penetration and treatment precision of PSs have been improved, providing a systematic reference for the development of efficient and low-toxicity tumor PDT strategies.