3 mercaptopropyl trimethoxysilane 3 mps 4 maleimidobutyric acid n hydroxysuccinimide ester gmbs polyvinylpyrrolidone pvp mw 40 000 anhydrous ethanol

Monodispersed silica colloids were ordered from Bangs Laboratories Inc. (3-Mercaptopropyl) trimethoxysilane (3-MPS), 4-Maleimidobutyric acid N-hydroxysuccinimide ester (GMBS), polyvinylpyrrolidone (PVP, MW~40,000), anhydrous ethanol, 1-pentanol (≥99%), and sodium citrate dihydrate (99%) were purchased from Sigma-Aldrich. Ammonia (28%) and tetra-ethyl orthosilicate (TEOS, 98%) were obtained from Fisher Scientific. The ELISA kits for EpCAM, CD24 and FRα were ordered from R&D Systems. Streptavidin conjugated β-Galactosidase (SβG), fluorescein-di-β-D-galactopyranoside (FDG), 3,3’-dioctadecyloxacarbocyanine perchlorate (DiO) lipophilic dye, Vybrant™ CM-DiO cell staining solution, and fluorescent nanoparticles (5% solid, Ex/Em 540/560 nm, actual size 46 nm) were purchased from Life Technologies. The detailed information of antibodies used in our studies was listed in Table S1 below. 1× phosphate-buffered saline solution (PBS) and SuperBlock buffer were from Mediatech, Inc and ThermoFisher Scientific, respectively. All other solutions were prepared with deionized water (18.2 MV-cm, Thermo Scientific). SβG and FDG were dissolved in PBS working solution (PBSW) at pH 7.4 which contain 0.5 mM DL-dithiothreitol (Sigma-Aldrich), 2 mM MgCl₂ (Fluka Analytical), and 5% bovine serum albumin (BSA, Sigma-Aldrich).