34 Nanoporous material assisted Lateral flow immunoassay (LFIA) for improved sensitivity and detection limit
LFIA is a low cost, disposable and fast tool, which is widely applied in diagnostics for the early detection of a broad set of clinically relevant biomarkers, such as detection of human chorionic gonadotropin (hCG) for pregnancy test  and p24 antigen in the human immunodeficiency virus (HIV) test . However, one of the significant limitations of LFIA is that it only provides qualitative and semi-quantitative analysis and relatively low sensitivity. In our work, we developed a nanoporous material assisted lateral flow immunoassay (LFIA) strip for quantitative analysis with improved sensitivity, working range, and lower limit of detection. Nanoporous materials with a porous structure were inserted between the conjugation and the nitrocellulose pads of a conventional LFIA strip setup. This additional pad delays the flow by increasing the fluidic resistance and thus extends the reaction time between the antibody and the analytes. The reported LFIA with a nanoporous materials shows a limit of detection of 0.01 ng/ml, a linear range from 0.01 ng/ml to 100 ng/ml (R2=0.966, log y= 1.91+0.027) for an IgG-anti-IgG model system, a definite improvement compared to a standard LFIA strip, which is non-quantitative in the detection range.
.S. A. Butler, S. A. Khanlian, and L. A. Cole, “Detection of Early Pregnancy Forms of Human Chorionic Gonadotropin by Home Pregnancy Test Devices,” Clin. Chem., vol. 47, no. 12, pp. 2131–2136, Dec. 2001.
 S. Workman et al., “Rapid detection of HIV-1 p24 antigen using magnetic immuno-chromatography (MICT),” J. Virol. Methods, vol. 160, no. 1–2, pp. 14–21, Sep. 2009.