qFlamma® Black01 Maleimide is a thiol  reactive universal dark quencher that the range of absorption covers from 400 to 800 nm with no native fluorescence. Black01 quencher displays high absorption coefficient, superb stability and aqueous solubility. Maleimides selectively label thiols of probes, peptide or protein via 1,4-addition pathway, without interacting with amines, to form thioether linkage. Maleimides apparently do not react with methionine, histidine or tyrosine, but they might react with primary amines under strong basic environment. We offer qFlamma® Black01 maleimide as a universal dark quencher in the construction of a variety of hybridization and custom-synthesized activatable probes for multiplexed bio-analysis, PCR, nucleic acid hybridization, etc.