Anchoring luminol based on Ti₃C₂-mediated in situ formation of Au NPs for construction of an efficient probe for miRNA electrogenerated chemiluminescence detection

An efficient electrogenerated chemiluminescence (ECL) nanoprobe (luminol-Au NPs-Ti₃C₂) was constructed based on Ti₃C₂Tx MXene (Ti₃C₂)-mediated in situ formation of Au NPs and anchoring luminol to fabricate a sensitive ECL biosensor for miRNA-155 detection. Herein, Ti₃C₂ with rich Ti vacancy defects was used as reducing agent, and Au NPs were generated in situ and anchored on the Ti₃C₂ (Au NPs-Ti₃C₂). Moreover, the Au NPs-Ti₃C₂ composites were used as a carrier and provided a large number of sites for the efficient linking of luminol through Au–N bonds to form stable luminol-Au NPs-Ti₃C₂. The immobilization of ECL emitters is a versatile strategy which not only shortens the electron transmission distance between luminol and electrode, but also provides naked catalytic predominated (111) facets of Au NPs with high electrocatalytic activity, significantly improving the ECL signal of luminol. Furthermore, a catalytic hairpin assembly (CHA) reaction was used, resulting in further amplification of the signal. As a result, the as-prepared ECL biosensor exhibited a linear range from 0.3 fM to 1 nM with a detection limit of 0.15 fM, and demonstrated high reliability of miRNA-155 detection even in human serum samples. The construction of a multifunctional ECL probe with excellent ECL emission opens a new chapter for the application of Ti₃C₂ in the field of bioanalysis. Graphical abstract: [Figure not available: see fulltext.].