LigandreplacementofcappedLAbyTChonthesurfaceof AuNPs
Fresh TCh was prepared according to the previous reported method (Ellman et al., 1961). The enzyme catalytic reaction of AChE with freshly prepared ATCh was conducted in 10 mM Tris–HCl buffer at pH 7.6 for 2h. The resulting solution was immediately used for further experiments. The final concentration of TCh was determined by spectrophotometric method using dithiobisnitrobenzoate (DTNB) as probe. A certain amount of AChE, ATCh and TCh was added in the LA capped AuNPs containing 10 mM Tris–HCl at pH 7.6, respectively. The dependence of the AuNPs aggregate status on the concentration of TCh was also investigated. Each of the mixtures was heated at 90 ◦ C for 5 min and the absorbance spectra of them were collected after being cooled to room temperature.