Development of a new sensitive immunostrip assay based on mesoporous silica and colloidal Au nanoparticles.

A new competitive immunostrip assay was developed to detect human serum albumin (HSA) in urine sample with use of conjugated monoclonal antibody gold nanoparticles (mAb-AuNPs) and mobile crystalline material (MCM)-41-HSA bioconjugate. To prepare the immunostrip, the colloidal AuNPs with an average particle diameter of 20 nm, was synthesized, labeled with antibody and applied on the conjugate pad as the detection reagent. Then, HSA was attached to the MCM-41 mesoporous nanoparticles and immobilized to a nitrocellulose membrane as the test line. In the optimized investigational conditions, the immunostrip could detect HSA in a high linear range (from 1 to 200 μg/ml) and low detection limit (ng/ml). The reliability of the testing procedure was examined by performing the immunostrip test with 30 urine samples and comparing the results with those obtained via immunoturbidimetry. The immunostrip was adequately sensitive and accurate for a rapid screening of HSA in the urine. This new strategy for competitive immunostrip design can be used and developed for other antigen based immunostrip assay.