Quantitative and rapid lateral flow immunoassay for cardiac troponin I using dendritic mesoporous silica nanoparticles and gold nanoparticles.

Acute myocardial infarction (AMI) is considered to be one of the predominant causes of human death; therefore, a rapid and accurate diagnostic method for AMI is urgently required. In this work, a highly sensitive lateral flow immunoassay (LFIA) platform was designed and fabricated for the quantitative determination of cardiac troponin I (cTnI) using a scanner, a smartphone and a colloidal gold immunoassay analyzer. To overcome the limitation of low sensitivity of traditional colloidal gold-based LFIA, three-dimensionally assembled gold nanoparticles (AuNPs) within a dendritic mesoporous silica nanoparticle (DMSN) scaffold were fabricated as signal labels. The assembly structure greatly enhanced the light extinction ability of a single label for signal amplification. The DMSNs@Au-based LFIA strips exhibited excellent detection performance including a high sensitivity (LOD = 70 pg mL^-1) and wide linear range (0.5-40 ng mL^-1) and precision with good specificity. The successful determination of cTnI by the test strips provides the ability to diagnose AMI at an early stage and expands the diagnostic window of AMI, while also having advantages such as low cost and user-friendliness. Therefore, we believe that the test strips fabricated in this work have great potential to be applied for practical clinical applications for the early and accurate diagnosis of AMI.