Supporting Information Synthesis of Cd-Functionalized Titanium Phosphate Nanoparticles and Application as Labels for Electrochemical Immunoassay

EXPERIMENTAL SECTION Materials and reagents Tetrabutyl titanate (TBOT), sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS) and phosphoric acid (H3PO4) were from Nanjing Chemical Reagent Co., Ltd. (Nanjing, China). Human IgG (HIgG) (Ag), rabbit anti-human IgG (Ab1), and goat anti-human IgG (Ab2) were purchased from Beijing Biosynthesis Biotechnology Co., Ltd. (Beijing, China). Bovine serum albumin (BSA), poly (allylamine hydrochloride) (PAH) (Mw≈15000), and Tween-20 were from Sigma-Aldrich. Glutaraldehyde (GLU), chloroauric acid (HAuCl4·3H2O) and trisodium citrate were obtained from Shanghai Reagent Company (Shanghai, China). Phosphate buffer saline (PBS) with different pH values were prepared by mixing the stock solution of NaH2PO4 and Na2HPO4, and then adjusting the pH with 0.1 M NaOH and H3PO4. HAc/NaAc solutions with different pH values were prepared by mixing the stock solutions of HAc and NaAc. All other reagents were of analytical reagent grade and used without further purification. Ultrapure fresh water obtained from a Millipore water purification system (MilliQ, specific resistivity is larger than 18 MΩcm, S.A., Molsheim, France) was used in all run.