DNA logic circuit coupled with enzymatic amplification for signal-enhanced, AND-gated imaging of inflammation-associated mRNAs

AND-gated molecular imaging, which relies on the simultaneous inputs of two or more biomarkers to produce one responsive signal, is of significance to improve the accuracy of lesion identification and disease diagnosis. However, the insufficiency of any one of these inputs and the cumulative efficiency loss in multiple reaction steps can limit the overall kinetic rate and the responsive signal intensity of the AND-gated imaging systems, hampering their performance in vivo. Here we report an in situ enzymatic amplification strategy to enhance the responsive signal of the AND-gated imaging of dual inflammation-associated messenger RNAs (mRNAs). In the design, a strand displacement reaction-based DNA logic circuit is programmed to respond to dual targets and output a single-stranded DNA, followed by downstream recognition with an enzyme-responsive molecular beacon, whose amplification of the responsive signal is specifically triggered by a translocated nuclease in inflammatory cells. Furthermore, by employing poly(beta-amino esters)-based nanocarriers to deliver the DNA probes, we demonstrated the signal-amplified sensing system enabled to monitor the progression of acute hepatitis in vivo via AND-gated imaging of interleukin-1 beta and interleukin-6 mRNAs.