Sodium hypochlorite (NaClO) and H2O2 were selleck chemical purchased from Beijing Chemical Reagents Company, Beijing, China. The stock solution (H2O2) was standardized by titration with a standard solution of KMnO4. All reagents were of analytical grade and the water used was doubly distilled. Apparatus All CL measurements were performed on the IFFM-E mode flow-injection chemiluminescence (FI-CL) analysis system (Xi’an Remax Company, Xi’an, China). It has two peristaltic pumps and one injection system synchronized by a microprocessor. All the reactor coils were made of Teflon tubing. The flow cell was a glass tube (i.d.

0.5 mm) connected with a selected high sensitivity, and low-noise photomultiplier find protocol tube. Light measurement data (ICL) were transferred to a computer automatically. Data acquisition and treatment were used with REMAX software running under Windows XP. The photoluminescence spectra and UV-visible absorption spectra were performed on a model F-4500 spectrofluorometer

(Hitachi, BIIB057 concentration Tokyo, Japan) and a model UV-3010 spectrophotometer (Hitachi, Japan), respectively. The transmission electron microscopy (TEM) images of the nanoparticles were acquired on a JEM-2010 F microscope. The CL spectrum was detected and recorded by a BPCL-2-KIC Ultra-Weak Luminescence Analyzer (Institute of Biophysics, Chinese Academy of Sciences) and combined with a flow injection system. Procedure A schematic diagram of the flow system was shown in Figure  1, in which four flow tubes were inserted into the NaOH (or sample) solution, CdTe NCs solution, H2O2 solution, and NaClO solution, respectively. One peristaltic pump (two

channels) was used to carry NaOH (or sample) solution and CdTe NC solution, and another pump (two channels) was used to carry H2O2 solution and NaClO solution, respectively. The pumps were started with the flow rate of 2.5 mL/min for several minutes until a stable baseline CL curve was recorded. The CdTe-H2O2 system could emit weak CL in NaOH solution (Figure  2b). However, when NaClO solution of 1.27 × 10-2 mol/L was mixed with the CdTe, and then injected into the stream, the CL signal was greatly enhanced (Figure  2a). Therefore, it could be assumed that NaClO strongly catalyzed the CdTe-H2O2 Thymidine kinase CL reaction. When estrogens were added to this CL system, the CL intensity decreased dramatically (Figure  2c). Figure 1 NaOH (or sample solution) (a), CdTe solution (b), NaClO solution (c), and H 2 O 2 solution (d). Figure 2 CL kinetic curves of H 2 O 2 -CdTe NC CL reaction. Results and discussion Synthesis of GSH-capped CdTe NCs A series of aqueous colloidal CdTe solution were prepared using the reaction between Cd2+ and NaHTe solution following the described method previously [21, 25–27], and little modification was made. Cd2+ precursor solutions were prepared by mixing solution of CdCl2 and GSH (used as stabilizer), then adjusted to pH 8.0 with 1 M NaOH. The typical molar ratio of Cd2+/Te/GSH was 4:1:10 [28] in our experiments.