Size-controlled preparation of monodisperse gold nanoparticles for detection of cardiac troponin Ⅰ by immunochromatography assay / 中华老年医学杂志

ABSTRACT

Objective To prepare the monodisperse,colloidal gold nanoparticles (AuNPs) with controllable sizes (50 nm,65 nm,79 nm and 102 nm) for the qualitative detection of cardiac troponin Ⅰ (cTnⅠ) by immunochromatography assay,and to evaluate the effectiveness of the detection.Methods Four kinds of monodisperse citrate-stabilized AuNPs were prepared using small AuNPs as growth centers (seeds) by a seeded growth thermal aging protocol.As controls,two conventional AuNPs (20 nm,40 nm) were prepared by the traditional citrate-reduction method.The mouse monoclonal antibody against cTnⅠ labeled AuNPs were dropped on polyester mat to make AuNPs conjugate pad.The detection line and quality control line of immunochromatography assay kits for detection of cTnⅠ were coated by mouse anti human cTnⅠ monoclonal antibody paired with antibody in AuNPs and goat anti mouse polyclonal antiboy respectively.The six kinds of AuNPs were employed as color-labels in immunochromatography assay kits for detecting cTnⅠ,and the corresponding detection effects were evaluated in signal intensity,sensitivity,specificity and stability.The assay kit with the best performance was chosen and compared with the commercialized kits for the detection of cTnⅠ in clinical samples.Results Four kinds of monodisperse AuNPs with large sizes of 50 nm,65 nm,79 nm,102 nm respectively were successfully synthesized by the seeded growth thermal aging method.The signal strength of four kinds of kits produced by the four large-sized AuNPs was superior to the kits produced by 20 nm AuNPs in detecting cTnⅠ(all P＜0.01).The signal strength of the kits produced by 65nm AuNPs showed the best performance among the six kinds of AuNPs(all P＜0.01).The lowest detectable limit was 0.50 ng/ml.To compare the agreement of results from chemiluminescent immunoassay versus the results from kits produced by 65nm AuNPs,100 serum samples have been used for detecting cTnⅠ.Their positive coincidence rate was 97.30％ and negative coincidence rate was 100％,the sensitivity and signal strength of the kits produced by 65nm AuNPs was superior to similar products which produced by ABON and Bottests company(all P＜0.01).Conclusions Monodisperse,largesized,citrate-stabilized AuNPs are controllably prepared by a seeded growth-thermal aging method.The development of large-size AuNPs-based immunochromatography assay kits is feasible.65 nm AuNPs can be a suitable candidate for cTnⅠ immunochromatography assay kit.Our findings provides a new idea for the current immunochromatography assay kits which still adopt small-sized AuNPs as color labels.