CdTe Quantum Dots, powder, hydrophilic Easily forms colloidal solutions in water. Terminated with -COOH group. Ideal for labeling purposes. Coupling with -NH2 groups can be achieved through EDC-mediated esterefication.
General labeling procedure for proteins (adopted from Wang et al. Nanoletters 2002, vol. 2, No. 8, 817-822): Reaction mixture containing 0.1 µM/mL CdTe quantum dots, 2 mg/mL protein, 1 mg/ mL sulfo-NHS (CAS# 106627-54-7), 10 mg/mL EDC (CAS# 25952-53-8) in pH 7.0 PBS buffer is prepared and stored for 2-4 h at room temperature and then stored at 4°C overnight. The precipitate (unconjugated Q-dots) if any is removed by centrifugation. The stock of ready-to-use product should be stored at 4°C. Optionally it can be dialyzed on a membrane with MWCO of 12000-14000 against pH 7.0 PBS buffer and stored at 4°C. Emission wavelength may slightly shift after labeling procedure