Fig. 3.

(a) Schematic of ssDNA-MoS₂-PEG-FA probe-based FRET platform for intracellular miRNA-21 detection. (b) Photoluminescence spectra of FAM-labeled miRNA-21 probes incubated with MoS₂ nanosheets with a series of concentrations. Reprinted with permission from Ref. [59]. Copyright 2018, ACS Applied Materials & Interfaces. (c) Schematic illustration showing the construction of the F–MoS₂ NSs and pH-dependent FRET, which is mediated by a conformation change of poly (DEA-r-BMA). (d) PL spectra of F–MoS₂ NSs at three different pH values of 7.4, 7.0, and 6.0. Insets are the corresponding confocal microscopy images of the solution. Scale bars are 100 μm. (e) Series of overlaid bright-field and fluorescence confocal microscopy images (top) and confocal microscopy images (bottom) showing the progressive enhancement of fluorescence intensity in the microcapsules during the growth of A549 tumor cells. Scale bars are 200 μm. Reprinted with permission from Ref. [63]. Copyright 2018, ACS Applied Materials & Interfaces.