Development of a gold immunochromatographic strip for the rapid detection of 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ) in catfish

Figures & data

Figure 1. The synthesis routes of the 2-CPAMOZ and 2-NPAMOZ.

Figure 2. The UV-VIS spectroscopy of 2-CPAMOZ, protein and conjugates: (a) confirmation of immunogen (2-CPAMOZ-KLH) and (b) confirmation of coating antigen (2-CPAMOZ-OVA, 2-CPAMOZ-BSA).

Figure 3. Standard curve for 2-CPAMOZ detection with mAb 4G11.

Table 1. Sensitivity and affinity of mAbs with different coating antigens.

Hybridoma	2-CPAMOZ-BSA		2-CPAMOZ-OVA
	A450nm	Inhibition rate (%)	A450nm	Inhibition rate (%)
2E4	1.71	43	1.44	49
3A2	1.65	40	1.32	46
3F4	1.97	41	1.56	44
4G11	2.1	43	2.1	54

Note: A_450nm: Absorbance at 450 nm with 0.03 μg/mL coating antigen concentration and 0.03 μg/mL mAb concentration.

Table 2. CR of mAb 4G11 with various drugs and marker residues.

Competitor	IC50 (ng/mL)	CR (%)
2-NPAMOZ	0.05	100
AMOZ	2.0	0.025
Furaltadone	400	<0.02
2-NPAOZ	>1000	<0.02
2-NPSEM	>1000	<0.02
2-NPAHD	>1000	<0.02
AOZ	>1000	<0.02
SEM	>1000	<0.02
AHD	>1000	<0.02
Furazolidone	>1000	<0.02
Nitrofurantoin	>1000	<0.02
Nitrofurazone	>1000	<0.02

Figure 4. The strip results for AMOZ in PBS: (a) Optimization of the concentrations of mAb and coating antigen. 1 = 0 ng/mL, 2 = 5 ng/mL. (b) Photo image of detection a series of 2-NPAMOZ in PBS by gold immunochromatographic strip. 1 = 0 ng/mL, 2 = 0.0025 ng/mL, 3 = 0.005 ng/mL, 4 = 0.01 ng/mL, 5 = 0.025 ng/mL, 6 = 0.05 ng/mL, 7 = 0.1 ng/mL.

Figure 5. The strip results for AMOZ in spiked catfish samples: (a) Photo image of detection a series of catfish samples spiked AMOZ by gold immunochromatographic strip. 1 = 0 μg/kg, 2 = 0.01 μg/kg, 3 = 0.025 μg/kg, 4 = 0.05 μg/kg, 5 = 0.1 μg/kg, 6 = 0.25 μg/kg. (b) The calibration curve for the strip result. The Y-axis is shown as the T/T₀ value; The X-axis is shown as the concentrations of AMOZ. T: the colour intensity of the given sample; T₀: the colour intensity of the blank sample.

Table 3. Analysis of AMOZ in spiked catfish samples by ic-ELISA, LC–MS/MS and strip assay.

		IC-ELISA		LC–MS/MS		Strip assay
Samples	Spiked level of AMOZ (ug/kg)	Recovery (%)±SD	CV (%)	Recovery (%)±SD	CV (%)	Quantitative detection		Qualitative detection
						Recovery rate (%)	CV (%)
Catfish	0	NC	NC	NC	NC	NC	NC	− − −
	0.02	90.2 ± 5.4	5.3	90.5 ± 6.4	6.9	92.32 ± 3.5	3.3	± ± ±
	0.05	94.5 ± 6.9	7.1	94.1 ± 5.9	6.4	98.5 ± 4.9	4.9	± ± ±
	0.1	112.7 ± 7.5	7.8	98.7 ± 4.8	4.3	119.3 ± 6.3	5.9	+ + +

Note: ±: weakly positive: the concentration of AMOZ was 0.01–0.1 μg/kg; +: positive: the concentration of AMOZ was ≥0.1 μg/kg. −: negative: the concentration of AMOZ was below 0.01 μg/kg. NC: not calculated.