Regeneration of large bone defects caused by trauma or tumor resection remains one of the biggest challenges in orthopedic surgery. Because of the limited availability of autograft material, the use of artificial bone is prevalent; however, the primary role of currently available artificial bone is restricted to acting as a bone graft extender owing to the lack of osteogenic ability. To explore whether surface modification might enhance artificial bone functionality, in this study we applied low-pressure plasma technology as next-generation surface treatment and processing strategy to chemically (amine) modify the surface of beta-tricalcium phosphate (β-TCP) artificial bone using a CH4/N2/He gas mixture. Plasma-treated β-TCP exhibited significantly enhanced hydrophilicity, facilitating the deep infiltration of cells into interconnected porous β-TCP. Additionally, cell adhesion and osteogenic differentiation on the plasma-treated artificial bone surfaces were also enhanced. Furthermore, in a rat calvarial defect model, the plasma treatment afforded high bone regeneration capacity. Together, these results suggest that amine modification of artificial bone by plasma technology can provide a high osteogenic ability and represents a promising strategy for resolving current clinical limitations regarding the use of artificial bone.

We apply particle based kinetic simulations to explore the characteristics of a low-pressure gas discharge driven by high-voltage (∼kV) pulses with alternating polarity, with a duty cycle of ≈ 1% and a repetition rate of 5 kHz. The computations allow tracing the spatio-temporal development of several discharge characteristics, the potential and electric field distributions, charged particle densities and fluxes, the mean ion energy at the electrode surfaces, etc. As such discharges have important surface processing applications, e.g. in the treatment of artificial bones, we analyse the time-dependence of the flux and the mean energy of the ions reaching the electrode surfaces, which can be both conducting and dielectric. Our investigations are conducted for argon buffer gas in the 40–140 Pa pressure range, for 1–5 cm electrode gaps and voltage pulse amplitudes ranging between 600 V and 1200 V.

Calcium phosphates are promising materials for artificial bone but lack of satisfied osteogenic ability on their surfaces. In the present study, we applied a low-pressure plasma technology to chemically (amine) modify the surface of calcium phosphates (hydroxyapatite or beta-tricalcium phosphate) using a CH4/N2/He plasm gas mixture to improve their osteogenic ability. The CH4/N2/He plasma treatment produced a thin, stable amine-rich carbon polymer on the surface of the calcium phosphates, and enhanced hydrophilicity, deep infiltration of cells into porous calcium phosphates, cell adhesion and osteogenic differentiation on the surface of calcium phosphates. In a rat calvarial defect model, the CH4/N2/He plasma treatment afforded calcium phosphates a significant higher bone regeneration capacity. Together, these results suggest that surface modification of calcium phosphates with CH4/N2/He plasma might improve osteogenic ability of calcium phosphates in vitro and in vivo.