Fig. 1. Experimental setup and materials. (a) Single-stranded DNA; (b) G-Quadruplex DNA; (c) diagram of the experimental setup

Fig. 2. Spectral graphs. (a) Spectral graph of the receptor laser in parallel polarization direction at 0 μmol/L K⁺; (b) spectral graph of the receptor laser in vertical polarization direction at 0 μmol/L K⁺; (c) spectral graph of the receptor laser in parallel polarization direction at 10 μmol/L K⁺; (d) spectral graph of the receptor laser in vertical polarization direction at 10 μmol/L K⁺

Fig. 3. Laser pumping threshold curves of TAMRA receptors in parallel and vertical polarization directions for different K⁺ concentrations at DNA molecule concentration 50 μmol/L. (a) 0 μmol/L; (b) 5 μmol/L; (c) 10 μmol/L; (d) 20 μmol/L;(e) 50 μmol/L

Fig. 4. Scatter plot of R_SER values of acceptor with potassium ion concentration

Table 1. Specific parameters of the configured G-quadruplex solution

Table 2. Curve slopes and laser thresholds in the parallel and perpendicular directions for acceptor lasers with different concentration of K⁺ in the solvent