Study of No Observed Adverse Effect Level of Nickel and Its Preliminary Evaluation Biocompatibility / 中国医疗器械杂志

The purpose of this study was to investigate the NOAEL of the nickel ion and provide with basic data for the biological evaluation of those medical devices containing nickel. Five groups SD rats were repeatedly exposed during 14 d respectively to nickel at first stage doses of 4.9, 3.7, 2.5 mg/(kg.d), and the second stage doses of 1.2, 0.25 mg/(kg.d) by the intravenous route. The results showed that the NOAEL of nickel ion is 0.25 mg/(kg.d) for SD rats, and the result was verified by subchronic systemic toxicity test of nickel alloy. The threshold of toxicological concern (TTC) of nickel is 150 μg/d (based on application of 100-fold uncertainty factor and a body weight of 60 kg)deduced by these data.

In Vitro Cytotoxicity Study of Nickel Ion / 中国医疗器械杂志

The purpose of this study was to investigate the cytotoxicity of the nickel ion and provide with basic data for the biological evaluation of those medical devices containing nickel. Seven cell lines were chosen. They were L929, h9c2(2-1), 293[HEK-293], hFOB1.19, THLE-3, H9 and IM-9 respectively. According to the principle of biological evaluation of medical devices, MTT method was chosen to test the cytotoxicity in different concentrations of nickel ion. For each cell line, the relative growth rate (RGR) was obtained and the cytotoxic grade was classified. Besides, IC50 values were calculated. As a result, it was found that the sensitivity was different among all cell lines. H9 was the most sensitive one, while the L929 was the most tolerant one. The concentration which is not above 1.25 mg/L was safe for all seven cell lines, because the cytotoxicity for all cells exposed in this concentration were not higher than grade 1. According to the criteria for medical devices, the concentrations not above 5 mg/L were safe for L929 cells. This result helps us to roughly assess the cytotoxicity and systematic toxicity caused by nickel contained in medical devices.

The investigation of nickel dissolution from nitinol under different extraction conditions in biological tests / 中国医疗器械杂志

The dissolution of nickel from nitinol alloy under different extraction conditions was investigated when biological tests of nitinol medical devices were carried out. It discussed the equivalence of these extraction conditions and found the best extraction conditions. In the experiment, two brands of nitinol were chosen and extracted under different extraction conditions according to GB/T 16886-12. Plasma emission spectrometer was used to analyse the concentration of nickel in extract liquid. The results show that there is no equivalence among these extraction conditions for nitinol materials. And it is suggested that (37 +/- 1) degree C, (72 +/- 2) h could be used as normal extraction condition and (70 +/- 2) degrees C, (24 +/- 2) h as accelerated extraction condition.