Directing Arrowhead Nanorod Dimers for MicroRNA In Situ Raman Detection in Living Cells

Abstract Directed self‐assembled nanomaterials with biological applications have attracted great interest. Here, arrowhead gold nanorod (NR) dimers with side‐by‐side and end‐to‐end motifs (known as AHSBS and AHETE dimers, respectively) presented based on selective modification of arrowhead NRs with DNA and polyethylene glycol, possessing intense surface enhanced Raman scattering (SERS) signals, are assembled for in situ intracellular microRNA detection. The arrowhead NR dimers are capable of recognizing target microRNA in a sequence‐specific manner as Raman signals significantly enhanced within dimers with both motifs. Following recognition, the dimers gradually disassemble, resulting in decreased SERS signals to achieve effective in situ Raman imaging and quantify the detection of target microRNA. The SERS intensity shows a linear relationship with intracellular target microRNA and a limit of detection of 0.011 amol ng RNA −1 for the AHETE dimer and 0.023 amol ng RNA −1 for the AHSBS dimer, respectively. The sensitivity for AHETE dimers is ≈2.1 times higher than that for AHSBS dimers, which is attributed to the small quantity of recognized molecules and stronger electrical enhancement, which causes greater SERS signals in the AHETE dimers. This approach opens up a new avenue for directed nanomaterials assembly and biological detection in living cells.