Figure 5.

(A) Spectrophotometric analysis procedure of maximum quantity of anti-AFP immobilized on the 1 mg Au NPs/Fe₃O₄/hemin/MCNTs. (I): 2.0 mL pH-adjusted Au NPs/Fe₃O₄/hemin/MCNTs composites; (II): (I) reacted with different concentration of anti-AFP; (III): the formed anti-AFP nanoprobes were separated and washed three times using magnet and redispersed in pH 6.5 PBS; (IV): Addition to suspension of 50 μL UHP and TMB, the solution turned blue immediately; (V): After 5 min, the above reaction was blocked with 2 M H₂SO₄ and the solution turned yellows; (VI): the above solution was seperated from anti-AFP nanoprobes using a magnet and then transferred to the 96-well plastic plate for OD analysis at the wavelength of 450 nm. (B) the analysis result of maximum quantity of anti-AFP immobilized on the 1 mg Au NPs/Fe₃O₄/hemin/MCNTs.