Nucleic acid hybridization on a plasmonic nanointerface of optical microfiber enables ultrahigh-sensitive detection and potential photothermal therapy

Quantifying the microRNA (miRNA) level and manipulating them in complex samples, such as serum, is of intense interest because miRNAs are important diagnostic markers. Here, we demonstrate an optical microfiber integrating of untrasensitive detection function and local photothermal therapy potential. A nanointerface consisting of GO supported Cu_2-xS nanoplates presented the localized surface plasmon resonance (LSPR) tuned to be consistent with the operation wavelength of the microfiber transducer. It enhanced the surface energy density of evanescent field, on which the miRNA sensing and therapy occurred. With evanescent field enhancement by the plasmonic nanointerface, the sensor exhibits an ultrahigh sensitivity for detecting microRNA at concentrations ranging from 0.1 aM to 10 pM. It is also capable of differentiating one-base mismatches of miRNA at ultralow concentrations (as low as 10 aM) in serum. The photothermal effect of nanointerface simultaneously endows the sensor with the potential for localized photothermal therapy. This work presents a possible approach for the in-situ integration of diagnosis and treatment in early stage.