The trimethoxysilyl functionality allows the pegylation of a variety of surfaces (e.g. glass, metals) and introduces PEG on hydroxylated surfaces in a one step procedure. Compared to Triethoxysilyl- the Trimethoxysilyl-PEG is more reactive. PEG crosslinking agent for biotinylation. The biotinyl functionality is used to attach avidin or streptavidin containing substrates. Pegylation by binding of biotinyl PEG to avidin and streptavidin is very specific and fast.