The practice of bone implants is the standard procedure for the treatment of skeletal fissures, or to substitute and re-establish lost bone. A perfect scaffold ought to be made of biomaterials that duplicate the structure and properties of natural bone. However, the production of living tissue constructs that are architecturally, functionally and mechanically comparable to natural bone is the major challenge in the treatment and regeneration of bone tissue in orthopaedics and in dentistry. In this work, we have employed a polymeric replication method to fabricate hydroxyapatite (HAP) scaffolds using gum tragacanth (GT) as a natural binder. GT is a natural gum collected from the dried sap of several species of Middle Eastern legumes of the genus Astragalus, possessing antibacterial and wound healing properties. The synthesized porous HAP scaffolds were analyzed structurally and characterized for their phase purity and mechanical properties. The biocompatibility of the porous HAP scaffold was confirmed by seeding the scaffold with Vero cells, and its bioactivity assessed by immersing the scaffold in simulated body fluid (SBF). Our characterization data showed that the biocompatible porous HAP scaffolds were composed of highly interconnecting pores with compressive strength ranging from 0.036 MPa to 2.954 MPa, comparable to that of spongy bone. These can be prepared in a controlled manner by using an appropriate binder concentration and sintering temperature. These HAP scaffolds have properties consistent with normal bone and should be further developed for potential application in bone implants.
A new series of lanthanum(iii) complexes was synthesized using a p-anisidine-appended 1-hydroxy-2-acetonapthanone (3) Schiff base and characterized via spectroscopic methods. The ligand was synthesized via sonication and the crystalline product was characterized using X-ray crystallography. The genotoxicity of the compound was assessed primarily by the bacterial reverse mutation (Ames) test and the in vitro mammalian chromosome aberration test; in both cases, the samarium complex 5 was found to be non-mutagenic. The anti-tumor activity of complexes 4, 5, and 6 was assayed against HeLa tumor cells and screened using the MTT assay. The IC50 value of complex 5 was found to be 34 ± 1.2 μg mL-1 and this compound exhibited superior activity towards the cells compared to 4 and 6. These results were further confirmed by Hoechst 33258 staining and AO/EI dual staining, which indicated that the cells underwent an apoptosis mechanism in a dose-dependent manner. The apoptosis was further confirmed by the formation of ladders in the DNA fragmentation assay, and the western blot analysis of complex 5 suggested that the cells underwent the caspase-3-dependent pathway with PARP cleavage. Furthermore, the docking studies of complex 5 with HSA showed that it was situated in a hydrophilic cavity held by the electrostatic attraction of four hydrogen-bonding interactions. PDB ID:1BNA binds with complex 5via strong π-π stacking interactions, which facilitate binding with the major grooves of DNA strands. The above-mentioned results illustrate that for complex 5, mitochondrion-mediated apoptosis occurs via caspase-3 activation. Complex 5 binds with DNA via intercalation because of S-phase cell cycle arrest in the HeLa cells.