Fig. 4: The non-FRET-WGM sensing system. | Nature Communications

Fig. 4: The non-FRET-WGM sensing system.

From: Demonstration of intracellular real-time molecular quantification via FRET-enhanced optical microcavity

Fig. 4

a Structural formula of R6G and R6GH. R6GH is a R6G analog with similar structure and molecular size. Right panel shows the molecular weight of R6GH determined by ESI mass spectrometer (cf. Fig S8 for full mass spectrum). b Absorption and emission spectra of DG and R6GH. Unlike R6G, R6GH does not absorb and emit light in the visible region. c Dose-dependent lasing spectra of DG in the presence of various concentrations of R6GH (solvent is 90%H2O + 10%EtOH. Only center peaks are shown, full spectra in SI Fig. S6c). d Wavelength shift (Δλ)-concentration curve of DG in the presence of R6GH. Δλ = λDG-in-R6GH-λDG-in-solvent. Data are presented as mean values ± SD (n = 3). e Threshold of DG in the presence of R6G (pink) or R6GH (red). Due to FRET, the lasing threshold of DG in R6G is much higher than that of R6GH. f Lasing thresholds of DG and R6G. As the R6G concentration increases, the thresholds of DG rise, indicating an increased energy loss of DG molecules.

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