An Ultrasensitive Label-Free Fluorescent Aptasensor Platform for Detection of Sulfamethazine

Figures & data

Figure 1 Schematic illustration of the fluorescent aptasensor for detecting SMZ based on label-free aptamer and FRET between RhoB and AuNPs.

Figure 2 Absorption spectra of AuNPs solutions in different sample solutions. AuNPs, 180 µL; NaCl, 30 mM; SMZ1S, 80 nM; SMZ, 1µg mL⁻¹.

Figure 3 Dynamic light scattering (DLS) of AuNPs in different substances. (A) AuNPs; (B) AuNPs-NaCl; (C) SMZ1S-AuNPs-NaCl; (D) SMZ-AuNPs; (E) SMZ-SMZ1S- AuNPs-NaCl. AuNPs, 180 µL; NaCl, 30 mM; SMZ1S, 80 nM; SMZ, 1 µg mL⁻¹.

Figure 4 Fluorescence spectra of RhoB in different sample solutions. AuNPs, 180 µL; NaCl, 30 mM; SMZ1S, 80 nM; RhoB, 2.5 µM; SMZ, 1µg mL⁻¹.

Figure 5 Sensitivity of the fluorescent aptasensor for SMZ detection. The corresponding linear calibration is inset. The SMZ concentration range is 1.25–40 ng mL⁻¹. AuNPs, 180 µL; NaCl, 30 mM; SMZ1S, 80 nM; RhoB, 2.5 µM.

Figure 6 Selectivity of the fluorescent aptasensor for SMZ. Reagents: sulfapyridine (SPD), sulfadimethoxine (SDM), sulfameter (SME), ofloxacin (OFL), chlortetracycline (TET), doxycycline (DOX), chloramphenicol (CAP), nitrofurantoin (NF). AuNPs, 180 µL; NaCl, 30 mM; SMZ1S, 80 nM; RhoB, 2.5 µM; SMZ and other antibiotics, 1 µg mL⁻¹.

Table 1 Mean Recoveries and Coefficients of Variation for the SMZ in Actual Water, Soil Sample Using Optimized Fluorescence Aptasensor (n = 5)

Sample	Spiked Concentration (ng mL^−1)	Mean Recovery (%) ± SD	CV (%)
Tap water	5	94.4 ± 8.7	9.3
	10	97.1 ± 6.6	6.8
	15	99.8 ± 6.4	6.4
	20	97.5 ± 4.1	4.2
Lake water	5	99.8 ± 4.6	4.6
	10	108.8 ± 2.0	1.8
	15	96.7 ± 2.8	2.9
	20	98.4 ± 6.7	6.8
Soil	5	96.2 ± 9.9	10.3
	10	103.4 ± 7.8	7.5
	15	108.8 ± 7.4	6.8
	20	105.2 ± 6.2	5.9

Abbreviations: SD, standard deviation; CV, coefficient of variation.