Biomimetic 3D DNA Nanomachine via Free DNA Walker Movement on Lipid Bilayers Supported by Hard SiO2@CdTe Nanoparticles for Ultrasensitive MicroRNA Detection

Herein, a novel three-dimensional (3D) DNA nanomachine with high walking efficiency via free DNA walker movement on biomimetic lipid bilayers supported by hard silica@CdTe quantum dots (SiO2@CdTe) was constructed for ultrasensitive fluorescence detection of microRNA. The synthesized SiO2@CdTe nanoparticles were adopted as the fluorescence indicator and spherical carrier of lipid bilayers, and then the DNA substrates were anchored on lipid bilayers with biomimetic fluidity through the cholesterol-lipid interaction. Once target microRNA-141 interacted with the 3D DNA nanomachine to release cholesterol labeled arm (Chol-arm), the Chol-arm could generate a series of strand displacement reactions by moving freely on the lipid bilayers, resulting in the releasement of numerous quenchers from the SiO2@CdTe nanoparticles and inducing a strong fluorescence signal. Impressively, compared with traditional 3D DNA nanomachine conjugating DNA substrates on hard surfaces (such as gold or silica) with limited reactivity, the proposed biomimetic 3D DNA nanomachine not only immobilized DNA substrates rapidly and effectively but also kept it with a favorable fluidity, which significantly enhanced the walking efficiency. As expected, the biomimetic 3D DNA nanomachine for fluorescence detection of microRNA-141 exhibited an excellent performance with a detection limit of 0.21 pM and presented promising properties in cell lysate detection and intracellular imaging. Thus, the described biomimetic 3D DNA nanomachine provided a novel avenue for sensitive detection of biomolecules, which could be useful for bioanalysis and early clinical diagnoses of disease.