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BackgroundWe evaluated the Bovine hydroxyapatite (BHA) structure. BHA powder was admixed with 5 and 10 wt% natural pumice (NP). Compression strength, Vickers micro hardness, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction studies were performed on the final NP-BHA composite products. The cells proliferation was investigated by MTT assay and SEM. Furthermore, the antimicrobial activity of NP-BHA samples was interrogated.ResultsVariances in the sintering temperature (for 5 wt% NP composites) between 1000 and 1300 °C, reveal about 700 % increase in the microhardness (~100 and 775 HV, respectively). Composites prepared at 1300 °C demonstrate the greatest compression strength with comparable result for 5 wt% NP content (87 MPa), which are significantly better than those for 10 wt% and those that do not include any NP (below 60 MPa, respectively).ConclusionThe results suggested the optimal parameters for the preparation of NP-BHA composites with increased mechanical properties and biocompatibility. Changes in micro-hardness and compression strength can be tailored by the tuning the NP concentration and sintering temperature. NP-BHA composites have demonstrated a remarkable potential for biomedical engineering applications such as bone graft and implant.

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Eighteen of the iron(III) and nickel(II) complexes with tetradentate thiosemicarbazidato ligands were synthesized and described, by analytical and spectroscopic methods. Two complexes as an example to the iron and nickel centered ones were crystallographically analyzed to confirm the molecular structures. Cytotoxic effects of the complexes on K562 chronic myeloid leukemia cells were determined by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay. For comparison, human umbilical vein endothelial cells (HUVECs) was used as a noncancerous cell line. While four of the iron(III) complexes exhibited the antileukemic effect with 50% inhibition of cell growth (IC50) values in the 3.4 to 6.9 μg/mL range on K562 cell line, the nickel(II) complexes showed no significant effect on both cell lines. The complexes Fe4, Fe5, and Fe6, bearing 4‐methoxy substituent exhibited relatively high antiproliferative activity on both cell lines. Complex Fe3 with 3‐methoxy and S‐allyl groups exhibited a selectivity between K562 and HUVEC cells by IC50 values of 6.9 and >10 μg/mL, respectively. Lipophilicity, a key parameter for bioavailability and oral administration, was found in the range of −0.3 and +1.3 that desired for drug active ingredients. The results were discussed in the context of a structure‐activity relationship.