Silver - calcium titanate – titania decorated Ti6Al4V powders: An antimicrobial and biocompatible filler in composite scaffold for bone tissue engineering application

Development of bioactive and antimicrobial nano-topography over selective laser melted Ti6Al4V implant and its in-vitro corrosion behavior

Additive manufacturing (AM) or 3D printing of bone defect models is gaining much attention in the biomedical field as it could significantly facilitate the development of customized implants with a high degree of dimensional accuracy. Due to their satisfactory biocompatibility and minimal stress shielding effect, Ti6Al4V (Ti64) alloys are increasingly preferred in the development of such implants. However, their poor osseointegration abilities and lack of antibacterial properties often cause implant loosening and microbial infections, leading to implant failure. To address these drawbacks, we propose in this work a simple surface modification approach of customized Ti64 alloys (3D printed Ti6Al4V) that enables the formation of porous calcium titanate (CT) over their surface as well as the incorporation of silver nanoparticles (AgNPs) into the thus formed porous network. The successful CT formation with the incorporation of AgNPs throughout the 3D printed Ti64 surface and their influence in changing the morphological and mechanical behaviour were studied by Raman spectroscopy, SEM, AFM, Contact angle measurement, XPS, HR-TEM and nano-indentation. Antibacterial studies using Staphylococcus aureus and Escherichia coli, and in-vitro cell studies using MG-63 cell lines showed that surface modified samples resulting from the proposed method exhibit satisfactory antimicrobial property and are highly biocompatible. The obtained surface modified samples also showed a significant improvement in corrosion resistance as compared to unmodified 3D printed Ti64 alloys. The improvement in corrosion resistance was revealed by electrochemical impedance Spectroscopy (EIS). Obtained results emphasis that thus surface modified 3D printed Ti64 alloys are promising candidates for hard tissue implant applications.

Induction of oxidative DNA damage, cell cycle arrest and p53 mediated apoptosis by calcium titanate nanoparticles in MCF-7 breast cancer cells

Background

The distinctive properties and high activity of calcium titanate nanoparticles (CaTiO₃-NPs) increase their use in many products. However, the cytotoxic and genotoxic effects of CaTiO₃-NPs in human cancer cell lines have not been well studied. Therefore, this study was conducted to explore CaTiO₃-NPs induced cytotoxicity, genomic instability and apoptosis in human breast cancer (MCF-7) cells.

Methods

Sulforhodamine B (SRB) and the alkaline comet assays were done to study cell viability and DNA damage induction, respectively. Apoptosis induction and cell cycle distribution were analyzed using flow cytometry. The level of intracellular reactive oxygen species (ROS) was studied, and the expression levels of p53, Bax and Bcl2 genes were also measured.

Results

The results of the Sulforhodamine B (SRB) cytotoxicity assay showed that viability of MCF-7 cells was not affected by CaTiO₃-NPs treatment for 24 h, however, exposure to CaTiO₃-NPs for 72 h caused concentrations dependent death of MCF-7 cells. Treatment with CaTiO₃-NPs for 72 h caused marked increases in intracellular ROS level and induced DNA damage. Treatment of MCF-7 cells with CaTiO₃-NPs also caused MCF-7 cell cycle arrest at the G0 and S phases and s triggered apoptosis of MCF-7 cells by causing simultaneous increases in the expression levels of apoptotic p53 and Bax genes and a decrease in the expression level of anti-apoptotic Bcl2 gene.

Conclusion

Collectively, it was concluded that CaTiO₃-NPs cause time- and concentration-dependent cytotoxic effects in human MCF-7 cells through induction of ROS generation, genomic instability and apoptosis. Thus it is recommended that further in vitro and in vivo studies are therefore recommended to understand the cytotoxic and biological effects of CaTiO₃-NPs.