posted on 2024-03-08, 13:36authored byXiaohong Zhong, Jing Hua, Ming Shi, Yifang He, Yong Huang, Beilei Wang, Liangliang Zhang, Shulin Zhao, Li Hou, Hong Liang
DNA motors have attracted extensive interest in biosensing
and
bioimaging. However, the amplification capacity of the existing DNA
motor systems is limited since the products from the walking process
are unable to feedback into the original DNA motor systems. As a result,
the sensitivities of such systems are limited in the contexts of biosensing
and bioimaging. In this study, we report a novel self-feedback DNAzyme
motor for the sensitive imaging of tumor-related mRNA in live cells
and in vivo with cascade signal amplification capacity. Gold nanoparticles
(AuNPs) are modified with hairpin-locked DNAzyme walker and track
strands formed by hybridizing Cy5-labeled DNA trigger-incorporated
substrate strands with assistant strands. Hybridization of the target
mRNA with the hairpin strands activates DNAzyme and promotes the autonomous
walking of DNAzyme on AuNPs through DNAzyme-catalyzed substrate cleavage,
resulting in the release of many Cy5-labeled substrate segments containing
DNA triggers and the generation of an amplified fluorescence signal.
Moreover, each released DNA trigger can also bind with the hairpin
strand to activate and operate the original motor system, which induces
further signal amplification via a feedback mechanism. This motor
exhibits a 102-fold improvement in detection sensitivity
over conventional DNAzyme motors and high selectivity for target mRNA.
It has been successfully applied to distinguish cancer cells from
normal cells and diagnose tumors in vivo based on mRNA imaging. The
proposed DNAzyme motor provides a promising paradigm for the amplified
detection and sensitive imaging of low-abundance biomolecules in vivo.