Abstract
A simple, sensitive and cost-effective method for the analysis of the mycotoxin aflatoxin B1 (AFB1) has been established based on controlled growth of immunogold. AFB1-BSA conjugate modified magnetic beads were employed as capture probe and anti-AFB1 antibody-coated gold colloids were used as detection probe for the immunological recognition of AFB1, as well as for signal transduction. The immune recognition event is converted into the gold enlargement signal which can be quantitatively measured by UV-vis spectroscopy. The autocatalytic enlargement of immunogold was conducted in aqueous solution containing chloroauric acid, hexadecyltrimethylammonium bromide and ascorbic acid. The reaction could be stopped by the addition of sodium thiosulfate. The final absorbance and resonance light scattering intensity were highly dependent on immunogold concentration. After gold enhancement, the sensitivity of the immunoassay was improved and total assay time reduced to 1 h. Under optimized conditions, the linear range and lower detection limit was 0.01-1 ng mL(-1) and 7 pg mL(-1), respectively. The proposed method offers great promise for sensitive detection of other mycotoxins and organic pollutants.
Highlights
The final absorbance depends on the amount of immunogold nanoparticles added, which is directly proportional to the concentration of aflatoxin B1 (AFB1) in the sample
It can be clearly seen that the rate of gold enlargement and final absorption intensity are highly dependent on and proportional to the initial concentration of immunogold (Fig. 5C), which provides a quantitative basis for signal amplification
Surface plasmon resonance signature of the enlarged AuNPs and the kinetics of the gold enlargement were monitored by UV-vis spectroscopy and resonance light scattering (RLS) technique
Summary
Gold nanoparticles (AuNPs) have attracted great attention in the bioanalytical field owing to their unique physical and chemical properties, such as easy preparation, simplicity of modification, superior compatibility and excellent optical property.[1,2] They are frequently employed as labels for different biological receptors, including enzymes, antibodies, aptamers/DNA, and other biomolecules,[3,4] which have been utilized for the detection of a wide variety of analytes.[5,6]Based on the unique distance-dependent surface plasmon resonance (SPR) property of AuNPs, numerous optical probes have been developed.[7,8] In addition, AuNPs have been extensively used for tag amplification.[9]. Several homogeneous detection formats have been developed to solve this problem.[24,25,26] The AuNPs were enlarged in aqueous solution, which shows some attractive attributes such as simpleness, low cost and high sensitivity. To study the influence of immunogold concentration, different amounts of gold seeds (5–50 μL) were added to 1.0 mL growth solution for gold enhancement.
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