[Effect of ultraviolet-photofunctionalization of titanium on protein adsorption and competition]

To study the adsorption behavior of bovine serum albumin (BSA) and fibrinogen (Fg) and the competition of them on titanium before and after ultraviolet (UV)-photofunctionalization, and to provide the evidence of photofunctionalization on the surface modification of titanium implants.

Titanium disks and sensors of quartz crystal microbalance-D (QCM-D) were stored and sealed in the dark for 4 weeks before being divided into two groups, namely the UV-treated group and control group. Samples in the UV-treated group were treated with UV rays for 48 hours. Then the Fg adsorbing property of disks in both groups was tested at 1, 12 and 24 h. Protein films of Fg and BSA formed on QCM sensors after 1 h incubation were imaged via atomic force microscopy (AFM). Then with QCM-D, for both surfaces the adsorption of Fg and BSA as well as the competition between them was tested by introducing proteins with different sequences.

After being incubated for 1 and 12 h, UV-treated group attracted more Fg[(0.250 ± 0.005) and (0.172 ± 0.006) mg] than control group did [(0.207 ± 0.004) and (0.144 ± 0.004) mg] (P < 0.05). However, after 24 h incubation, Fg residual on the UV-treated group [(0.080 ± 0.003) mg] was smaller than that in the control group [(0.127 ± 0.004) mg] (P < 0.05). AFM showed protein clustered more densely on UV-treated surfaces than control surfaces and QCM displayed the same result. In addition, when Fg was introduced into QCM-D after BSA, the mass of protein film increased on both surfaces. However, when BSA was introduced after Fg, the mass of protein film on the control group had no change, but slightly decrease on the UV-treated group.

UV-photofunctionalization promotes protein adsorption but has no influence on the competition between Fg and BSA.