Texas Red BCN

Texas Red BCN is a clickable derivative of Sulforhodamine 101 (Texas Red), a widely used red fluorescent dye for labeling biomolecules, particularly peptides and oligonucleotides. Texas Red is characterized by its high quantum yield and photostability, properties that have established its widespread use in fluorescence-based applications. Nevertheless, its hydrolytic instability and limited aqueous solubility often impede efficient bioconjugation. To overcome these challenges, the BCN derivative incorporates a polyethylene glycol (PEG) linker, which enhances hydrophilicity and reduces steric hindrance. This modification improves conjugation efficiency while preserving the native interactions of the labeled biomolecules. The bicyclononyne (BCN) moiety enables strain-promoted azide-alkyne cycloaddition (SPAAC) with azido groups, forming stable triazole linkages under catalyst-free conditions. In addition, unlike dibenzocyclooctyne (DBCO), BCN also reacts efficiently with tetrazines through an inverse electron-demand Diels-Alder (IEDDA) reaction. This reaction is rapid, selective, and bioorthogonal, allowing labeling of biomolecules under physiological conditions without the need for metal catalysts or disruption of native biological processes.