Fucoidan (Undaria pinnatifida)/Polydopamine Composite-Modified Surface Promotes Osteogenic Potential of Periodontal Ligament Stem Cells.

Fucoidan, a marine-sulfated polysaccharide derived from brown algae, has been recently spotlighted as a natural biomaterial for use in bone formation and regeneration. Current research explores the osteoinductive and osteoconductive properties of fucoidan-based composites for bone tissue engineering applications. The utility of fucoidan in a bone tissue regeneration environment necessitates a better understanding of how fucoidan regulates osteogenic processes at the molecular level. Therefore, this study designed a fucoidan and polydopamine (PDA) composite-based film for use in a culture platform for periodontal ligament stem cells (PDLSCs) and explored the prominent molecular pathways induced during osteogenic differentiation of PDLSCs through transcriptome profiling. Characterization of the fucoidan/PDA-coated culture polystyrene surface was assessed by scanning electron microscopy and X-ray photoelectron spectroscopy. The osteogenic differentiation of the PDLSCs cultured on the fucoidan/PDA composite was examined through alkaline phosphatase activity, intracellular calcium levels, matrix mineralization assay, and analysis of the mRNA and protein expression of osteogenic markers. RNA sequencing was performed to identify significantly enriched and associated molecular networks. The culture of PDLSCs on the fucoidan/PDA composite demonstrated higher osteogenic potency than that on the control surface. Differentially expressed genes (DEGs) (n = 348) were identified during fucoidan/PDA-induced osteogenic differentiation by RNA sequencing. The signaling pathways enriched in the DEGs include regulation of the actin cytoskeleton and Ras-related protein 1 and phosphatidylinositol signaling. These pathways represent cell adhesion and cytoskeleton organization functions that are significantly involved in the osteogenic process. These results suggest that a fucoidan/PDA composite promotes the osteogenic potential of PDLSCs by activation of critical molecular pathways.

The relationship between the structures of periphery ligands and the DNA binding mode of [Ru(II)(1,10-phenanthroline)(L1L2)dipyrido[3,2-a:2',3'-c]phenazine](n+) (L1=Cl or pyridine and L2=pyridine, n=1,2).

The binding modes of the [Ru(II)(1,10-phenanthroline)(L(1)L(2)) dipyrido[3,2-a:2',3'-c]phenazine](2+) {[Ru(phen)(py) Cl dppz](+) (L(1)=Cl, L(2)=pyridine) and ([Ru(phen)(py)(2)dppz](2+) (L(1)=L(2)=pyridine)} to native DNA is compared to that of the [Ru(II)(1,10-phenanthroline)(2)dipyrido[3,2-a:2',3'-c]phenazine](2+) complex ([Ru(phen)(2)dppz](2+)) by various spectroscopic and hydrodynamic methods including electric absorption, linear dichroism (LD), fluorescence spectroscopy, and viscometric titration. All measured properties, including red-shift and hypochromism in the dppz absorption band, nearly perpendicular molecular plane of the dppz ligand with respect to the local DNA helix axis, prohibition of the ethidium binding, the light switch effect and binding stoichiometry, increase in the viscosity upon binding to DNA, increase in the melting temperature are in agreement with classical intercalation of dppz ligand of the [Ru(phen)(2)dppz](2+) complex, in which both phenanthroline ligand anchored to the DNA phosphate groups by electrostatic interaction. [Ru(phen)(py)(2) dppz](2+) and [Ru(phen)(py) Cl dppz](+) complexes had one of the phenanthroline ligand replaced by either two pyridine ligands or one pyridine plus a chlorine ion. They exhibited similar protection from water molecules, interaction with DNA bases, and occupying site that is common with ethidium. The dppz ligand of these two Ru(II) complex were greatly tilted relative to the DNA helix axis, suggesting that the dppz ligand resides inside the DNA and is not perpendicular relative to the DNA helix axis. These observation suggest that anchoring the [Ru(phen)(2)dppz](2+)complex by both phenanthroline is essential for the dppz ligand to be classically intercalated between DNA base-pairs.