Feasibility studies for assaying alpha-fetoprotein using antibody-activated magnetic nanoparticles

Figures & data

Figure 1 Illustration of mechanism of immunomagnetic reduction to detect biotargets. (A) Each magnetic nanoparticle oscillates individually with the applied alternative-current magnetic field before binding with biotargets. (B) Portions of magnetic nanoparticles become larger due to the binding with biotargets. The bound magnetic nanoparticles in (B) contribute to the reduction in the alternative-current magnetic susceptibility of the reagent.

Table 1 Information on interference materials used for the IMR and ELISA interference tests in this work

Interfering material	Related disease	Normal reference level	Concentration used
Hemoglobin	Hemolysis	<500 μg/mL	600 μg/mL 1000 μg/mL
Conjugated bilirubin	Jaundice	<2 μg/mL	5 μg/mL 10 μg/mL
Triglyceride	Hypertriglyceridemia	500–1500 μg/mL	2000 μg/mL
Vascular endothelial growth factor	Malignancy	<0.05 ng/mL	0.1 ng/mL

Abbreviations: IMR, immunomagnetic reduction; ELISA, enzyme-linked immunosorbent assay.

Figure 2 AFP concentration-dependent IMR (%) (solid circles with the solid line) and OD₄₅₀ (open squares with the dashed line) obtained with IMR and ELISA, respectively.

Note: Points represent mean ± standard deviation.

Abbreviations: AFP, alphafetaprotein; IMR, immunomagnetic reduction; ELISA, enzyme-linked immunosorbent assay; OD, optical density.

Figure 3 AFP concentration in sera of early-stage HCC patients detected by ELISA and IMR, respectively.

Note: Points represent mean ± standard deviation.

Abbreviations: AFP, alphafetaprotein; HCC, hepatocellular carcinoma; ELISA, enzyme-linked immunosorbent assay; IMR, hepatocellular carcinoma.

Figure 4 Contributions from various kinds of interfering materials to (A) IMR (%) and (B) OD₄₅₀ measured with IMR and ELISA, respectively. The AFP concentration in each sample is 500 ng/mL.

Notes: The label “None” means there is no interfering material in the 500-ng/mL AFP solution; bars represent mean ± standard deviation.

Abbreviations: AFP, alphafetaprotein; IMR, immunomagnetic reduction; ELISA, enzyme-linked immunosorbent assay; OD, optical density; VEGF, vascular endothelial growth factor.

Figure 5 AFP concentrations in sera of normal people and HCC patients. The AFP concentrations are detected via IMR. The sample numbers are 17 for the normal group and 19 for the HCC group.

Note: Points represent mean ± standard deviation.

Abbreviations: AFP, alphafetaprotein; HCC, hepatocellular carcinoma; IMR, immunomagnetic reduction.