Fig nbsp xA A XPS survey spectra of a

The objective of this camptothecin apoptosis study was to deposit tantalum oxide layers onto titanium substrates with PAD technique and to investigate on the effect of the coating on the proliferation and differentiation of osteoblast both on cellular and molecular levels.
2. Materials and methods
2.1. Materials
Titanium (Ti) disks (diameter: 15 mm; thickness: 3 mm) were obtained from Northwest Institute for Non-ferrous Metal Research, China. TaCl5 (99.9%) polyethylenimine (PEI, MW 10 kD, 99%) and Hoechst 33258 were supplied by Sigma Chemical Co. (MO, USA). BCA kit, cell counting kit-8 (CCK-8) and alkaline phosphatase (ALP) assay kit were purchased from Beyotime Co. (Beijing, China). Rhodamine-phalloidin was obtained from Invitrogen Co. (USA). Other chemicals were purchased from Oriental Chemical Co. (Chongqing, China).
2.2. Precursor solution preparation
The precursor solution was prepared by dissolving 0.25 g of TaCl5 into 5 mL water containing 20% (v/v) hydrogen peroxide. The mixture solution was stirred for 5 min, resulting in a thalamus turbid solution. Next, 0.6 g of citrate was added and stirred for another 30 min to obtain an apparent solution. Subsequently, 0.6 g of PEI was added to the mixture solution, resulting in a brown solution. The final concentration of Ta was adjusted to be 0.12 mmol/mL.