Fig. 4. The fluorescence emission spectrum of the sensing system. Experimental conditions: all measurements were performed at 25 °C with excitation at 510 nm. (a) RB; (b) RB + AuNPs; (c) RB + AuNPs + NaCl; (d) RB/AuNPs + NaCl + aptamer; (e) RB + AuNPs + NaCl + aptamer + acetamiprid.