Construction of the 0D/2D heterojunction of Ti3C2Tx MXene nanosheets and iron phthalocyanine quantum dots for the impedimetric aptasensing of microRNA-155

A promising nanocarrier of the complementary DNA (cDNA) toward miRNA-155 was synthesized on the basis of the nanohybrid type of Ti3C2Tx MXene nanosheets decorated using iron phthalocyanine quantum dots (FePc QDs) (denoted as Ti3C2Tx@FePcQDs) to construct a novel ultrasensitive impedimetric aptasensing system for microRNA-155 (miRNA-155). Owing to π–π* stacking interaction between Ti3C2Tx nanosheets and FePc QDs, the homogeneous nanostructure of the Ti3C2Tx@FePcQD nanohybrid that comprises mixed-valence states (Ti2+/Ti3+ and Fe2+/Fe3+), multicomponent (Ti-O and Ti-C), and various N-related groups was achieved. The constructed Ti3C2Tx@FePcQDs-based aptasensor displayed an ultrahigh sensitivity for detecting miRNA-155 with a low detection limit of 4.3 aM (S/N = 3) within the miRNA-155 concentration ranging from 0.01 fM to 10 pM. Compared with the individual component-based aptasensors and other reported miRNA-155 aptasensors, the proposed impedimetric aptasensing system exhibited substantial merits of a feasible preparation process, non-use of labels or electrochemical indicators, fast response time, and comprehensive sensing performances for detecting miRNA-155. This strategy for determining miRNAs can extensively be applied as the platform for anchoring other kinds of aptamers in detecting diverse targets, thus indicating its great potential application for the early diagnosis of cancer biomarkers.