The Amino-(PEG)n-t-butyl ester reagents are Amino-proteins or surfaces such as beads, nanoparticles Functionalization of solid surfaces, such as quantum dots, self-assembled monolayers and nanoparticles, with polyethylene glycol spacers significantly reduces nonspecific protein binding. Amino-(PEG)n-t-butyl ester reagents used with (PEG)n amine reagents in surface modification can form a hydrophilic “lawn” of methyl ether-terminated PEGs with periodic exposed carboxy-terminated PEGs. The exposed carboxy groups can be coupled to affinity ligands using the carbodiimide coupling reaction with EDC and sulfo-NHS.