Fig. 2: Signal amplification strategies.
To enhance the S/N or S/B ratio, the CRISPR–dCas9 system amplifies fluorescence signals by recruiting multiple FPs to the target site. a In the simplest approach, a single dCas9 protein was engineered to carry up to three FPs. b Alternatively, sgRNA was modified to include multiple RNA aptamer sequences, which are recognized by their corresponding coat proteins fused to FPs. c Another strategy involved tethering multiple peptide tags to dCas9 instead of FPs. These tags were then labeled with specific nanobodies conjugated to FPs, enabling the recruitment of a higher number of FPs compared with direct FP tethering.
