Antibody-based sensors have made outstanding contributions to the fields of molecular biology and biotechnology. Nowadays, a novel powerful fluorescent immunosensor strategy named Quenchbody (Q-body) has been applied to the detection of a range of antigens in a rapid, simple, and sensitive manner. Q-bodies, which are made by conjugation of fluorescent probes to antibodies, have merits such as no need of additional reagents and availability of sensitivity without need of long incubation.
Q-body works on the mechanism of antigen-dependent removal of quenching effect on popular fluorophores such as carboxyltetramethylrhodamine (TAMRA), which is incorporated to a specific position(s) of a single chain antibody (scFv) or Fab fragment. The primary reason of quenching is photoinduced electron transfer (PET) from conserved tryptophan (Trp) residues in the variable region, and secondarily, the other dye incorporated to the other site. Using this Q-body technology, just mixing a Q-body with antigen and measuring the fluorescence intensity enables antigen quantitation. Since no washing step is necessary, it is a remarkably simple and rapid quantification method, still allowing the use of several organic dyes with different colors. Q-bodies has been use to successfully quantify a range of biomolecules including small haptens, peptides, and larger proteins.
Ultra-Quenchbodies (UQ-bodies) refer to doubly labeled Fab Q-bodies, in which the same dye was incorporated to both the H and L chains, resulted in deeper quenching and a greater antigen-dependent release, due to H-dimer formation and Trp-mediated PET. Compared with single labeled Q-bodies, double-labeled UQ- bodies showed generally higher responses; Especially, a hetero double-labeled Fab has been successfully used to monitor changes in FRET that are dependent on a conformational change that occurs upon the binding of the antigen.
The services we provide:
Synthesis of Q-Bodies (scFv-type)
Generation of Ultra-Quenchbodies (Fab-type)
Generation of hetero double-labeled Fab-type Ultra-Quenchbodies
Generation of UQ-bodies using recombinant Fab fragments (E.coli)
CD’s Custom Technology Teams are experienced in performing both small-scale and large-scale antibody generations and purifications. Please feel free to contact us if you have any questions regarding our service.