Biological Property Investigation of Nitinol Surface Implanted with Tantalum

doi:10.15541/jim20220140

Abstract

Abstract:

Nitinol vascular stent can trigger thrombosis and restenosis, but lacks the ability to rehabilitate with injury still to the blood vessel wall. Thus, surface modification to the stent is indispensable for nitinol surfaces to realize biological functions of anticoagulation and accelerate endothelialization. Here, tantalum ions were implanted into nitinol surfaces by plasma immersion ion implantation and deposition (PIII&D). Physicochemical and biological characteristics of the modified nitinol surfaces were analyzed. The results show that the Ta, Ta/Ta₂O₅, and Ta/Ta₂O_5-_x/Ta₂O₅-containing modified layers are formed on nitinol surfaces with extension of implantation time. Among all samples, the modified surface containing Ta/Ta₂O_5-_x/Ta₂O₅ phase possesses better hydrophilicity and provides more sites for cell attachment to promote initial cell adhesion and proliferation. Compared with the solely Ta-bearing surface, the modified surface containing Ta/Ta₂O_5-_x/Ta₂O₅ shows superior hemocompatibility, on which fewer adhered platelets are observed, maitaining an inactive and original spherical shape. Besides, the hemolysis rates of all samples are far below the threshold value of 5%, indicating that hemolysis hardly happens. The results indicate that Ta ion implantation modified nitinol stent has a potential application in reducing thrombosis and accelerating endothelialization.

Key words: nitinol, tantalum, ion implantation, hemocompatibility

CLC Number:

TQ174

WU Ling, TAN Ji, QIAN Shi, GE Naijian, LIU Xuanyong. Biological Property Investigation of Nitinol Surface Implanted with Tantalum[J]. Journal of Inorganic Materials, 2022, 37(11): 1217-1224.

Figures/Tables 11

Table 1 Process parameters of tantalum plasma immersion ion implantation and deposition

Parameters	Target	Cathodic arc
Voltage pulse duration/μs	500	800
Pulsing frequency/Hz	10	10
Implantation voltage/kV	-15	-
Implantation time/min	30, 60, 120	-

Fig. 1 SEM images of surface morphologies of different samples

Fig. 2 XRD patterns of different samples

Fig. 3 (a) XPS full spectra and (b-d) Ta4f high-resolution XPS spectra detected from samples’ surfaces The color figures can be obtained from online edition.

Fig. 4 Contact angles of various samples The color figures can be obtained from online edition (**: p<0.01)

Fig. 5 Polarization curves of various samples in physiological saline. The color figure can be obtained from online edition

Table 2 Corrosion potentials and corrosion currents of various samples

Sample	E_corr/V	I_corr/(A∙cm^-2)
NiTi	-0.288	5.65×10^-6
30Ta-NiTi	-0.288	6.37×10^-6
60Ta-NiTi	-0.261	6.69×10^-6
120Ta-NiTi	-0.251	6.62×10^-6

Fig. 6 Fluorescent images of HUVECs adhered to various samples at 1, 4, and 24 h The color figures can be obtained from online edition

Fig. 7 Live (green)/dead (red) cell staining fluorescent images of HUVECs seeded on samples for 4 d The color figures can be obtained from online edition

Fig. 8 Cell viability of HUVECs cultured on sample surfaces for 1, 4 and 7 d The color figures can be obtained from online edition *: p<0.05, *: p<0.01, ***: p<0.001

Fig. 9 (a) SEM images of adhered platelets on sample surfaces and (b) hemolysis rate of various samples Arrows indicate the stimulated platelets; The color figures can be obtained from online edition

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