Immunosensor for realtime monitoring of the expression of recombinant proteins during bioprocess

Recombinant protein expression and purification are crucial in modern life sciences research. A fluorescent immunosensor termed Quenchbody (Q-body) was developed for real-time monitoring of FLAG-fused protein expression. Detection results showed that the limit of detection of the 3 × FLAG peptide detected by the TAMRA-labeled anti-FLAG Q-body was as low as 3.1 nM, with a half-maximal effective concentration of 21.4 nM. Furthermore, the anti-FLAG Q-body was used for detecting different proteins fused with a FLAG-tag at the N- or C-terminal. Subsequently, the constructed Q-body was used to monitor the real-time fermentation process of single-strand DNA-binding protein in Escherichia coli. Unlike previously reported Q-bodies that widely used Fab or scFv, the present study used a full-length anti-FLAG IgG for the first time. Owing to its excellent detection speed and sensitivity, the FLAG Q-body immunosensor has the potential to quantify and monitor target recombinant proteins in multiple biological processes in real-time.