Construction of mercapto-ended telechelic poly(ethylene glycol) brush and these surface application

Construction of PEG tethered chain on a gold surface by the consecutive treatments with a mercapto-ended semitelechelic PEG (MeO-PEG-SH; MW=2k), followed by a mercapto-ended telechelic PEG(SH-PEG-SH; MW=5k). By changing the density of pre-constructed MeO-PEG-SH(2k) tethered chain surface, the amount of modified SH-PEG-SH could be controlled, which was monitored by a surface plasmon resonance (SPR) instrument. Maleimide-installed BSA was immobilized on the constructed PEG surface via the Michael reaction of the maleimide and mercapto group at the PEG chain end. With the increasing SH-PEG-SH(5k) in the region of low SH-PEG-SH(5k) density, the amount of maleimide-BSA increased. In the high SH-PEG-SH(5k) region, however, the immobilized amount of maleimide-BSA decreased, indicating loop formation of the SH-PEG-SH(5k) on the surface. Under the suitable modification conditions, ideal PEG tethered chain surface possessing the effective amount of the mercapto ends were constructed. The surface possessing the mercapto-ended PEG tethered chain thus prepared can be regarded as a promising tool for protein immobilization surface.