Titanium tetrachloride

Mica (powder type) was purchased from CQV Co., Ltd. (Jincheon, Korea). Titanium tetrachloride (99.9%) and silicone oil (viscosity = 100 cSt) were purchased from Sigma-Aldrich (Burlington, MA, USA). Sodium hydroxide (40.0%) and ethanol (EtOH, 99.9%) were purchased from Samchun Chemical Company (Seoul, Korea). All chemicals were used as received without any additional purification.

Molybdenum disulfide (MoS₂, ~6 μm), n-butylmagnesium chloride (BuMgCl, 2.0 M in THF), triethylaluminum (TEA, 1.0 M in hexane), diisobutylphthalate (DIBP), and titanium tetrachloride (TiCl₄, >99%) were purchased from Sigma-Aldrich (Seoul, Korea) and used as received. Cyclohexylmethyldimethoxysilane (CHMDMS) donor and polymerization-grade propylene were received from Korea Petrochemical Ind. Co., Ltd., Ulsan, Korea. n-Hexane was distilled from sodium/benzophenone under N₂ prior to use.

Endogenous H₂O₂ levels were determined according to the method described previously by Brennan and Frenkel (1977 (link)), with some modifications. H₂O₂ was extracted by homogenization of 0.5–1 g tissue in 2 ml cold acetone. After centrifugation (5 min at 12,000g), the pellet was discarded and a 0.5 ml extract was collected. A titanium reagent (50 μl 20 % titanium tetrachloride in concentrated HCl, v/v, Sigma-Aldrich, Poland) was added to the 0.5 ml extract, followed by the addition of 0.1 ml NH₃ (25 %; v/v) to precipitate the peroxide-titanium complex. After 5 min centrifugation at 10,000g, the supernatant was discarded and the precipitate was repeatedly washed in 1 ml acetone and centrifuged again for 5 min at 10,000g. The precipitate was solubilized in 1 ml 1N H₂SO₄ and brought to a final volume of 2 ml. The absorbance of the obtained solution was read at 415 nm against a water blank. The concentration of peroxide in the extract was determined by comparing absorbance against a standard curve representing the titanium–H₂O₂ complex over a range from 0 to 20 μmol ml⁻¹. All H₂O₂ measurements were normalized to tissue fresh weight.