SFB (Succinimidyl 4-formylbenzoate)
A heterobifunctional crosslinker used to modify amine-containing biomolecules or surfaces to directly incorporate benzaldehyde moieties. This reagent, when combined with SANH (Succinimidyl 6-hydrazinonicotinamide acetone hydrazone) is ideal for modifying biomolecules in preparation for conjugation. SANH and SFB will modify proteins by incorporating hydrazine and benzaldehyde moieties, respectively, in a single step. The alkyl hydrazone protecting group on SANH readily hydrolyzes in acidic or neutral pH (4.5-7.4) and the liberated hydrazine moiety reacts with the aldehyde modified biomolecules to produce stable hydrazone conjugates (see below). Unlike the classical maleimide/thiol linkers, proteins modified with SANH or SFB are stable for months.