Safety assessment of subtilisin QK in rats.

BACKGROUND: Subtilisin QK is a serine protease in the subtilisin family, and is fermented by Bacillus subtilis QK02. The fibrinolytic activity of subtilisin QK was measured by detecting low molecular weight degradation products using a spectrophotometric method developed by Japan Bio Science Laboratory Co., Ltd. Subtilisin QK powder can maintain its fibrinolytic activity for more than 24 months when it is stored at room temperature and protected from light. Our previous results showed that subtlisin QK directly degraded cross-linked fibrins in the fibrin plate assay and effectively inhibited thrombosis in the mouse thrombus model. The aim of this study was to determine the acute toxicity, potential subchronic toxicity, and safety pharmacology of subtilisin QK in Sprague-Dawley (SD) rats. METHODS: In the acute toxicity study, a single oral dose of 100,000 FU/kg was administered to 10 female and 10 male SD rats. In the 28-day subchronic toxicity, 60 female and 60 male SD rats were randomly assigned to four experimental groups (daily oral dose of 0, 2500, 7500 and 25,000 FU/kg). In the safety pharmacology study, 20 female and 20 male SD rats were randomly assigned to four experimental groups (single oral dose of 0, 500, 1500 and 5000 FU/kg). RESULTS: No death occurred and no adverse effects were observed in the acute toxicity study at a dose of 100,000 FU/kg. In the 28-day subchronic toxicity study, several hematological and blood biochemical parameters showed increases or decreases; however, due to the lack of a dose-response relationship, these differences were considered unrelated to treatment. In the safety pharmacology study, no adverse effects were observed on the central nervous of SD rats post-administration up to a dose of 5000 FU/kg subtilisin QK. CONCLUSION: The results showed that oral consumption of subtilisin QK is of low toxicological concern. No adverse effects were observed at doses of 2500, 7500, and 25,000 FU/kg in the 28-day subchronic toxicity, and the no-observed-adverse-effect level (NOAEL) of subtilisin QK was 25,000 FU/kg.

The application of nanoparticles in biochips.

A nanoparticle is a microscopic particle with at least one dimension less than 100 nm, which plays an important role in the area of intense scientific research. In recent years, the application of gold nanoparticles instead of fluorescence dyes and enzyme-conjugation in biochips is very common. For example, Au nanoparticles labeling method was applied in many DNA-detection methods, and a novel readout scheme for gold nanoparticle-based DNA microarrays was studied relying on "Laser-Induced Scattering around a nanoAbsorber" and nanogold electrode, and the colorimetric detection using gold label plus silver stain was also developed. The technology is a good combination of gene technology and nanotechnology. At the same time, a number of scientists from different countries have paid more attention to the application of nanoparticles in biochips and gotten some new patents for it.