Three different kinds of molecular sieves (mesoporous materials SBA-15 and MCM-41, microporous zeolite Y) have been used as the modifiers to fabricate the modified carbon paste electrodes (MCPEs). Based on these MCPEs, a novel electrochemical immunoassay for cardiac troponin I (cTnI) combining the concepts of the dual monoclonal antibody ‘‘sandwich’’ principle, the silver enhancement on the nanogold particles, and the anodic stripping voltammetry is described. Four main steps were carried out to obtain the analytical signal, i.e. electrode preparation, immunoreaction, silver enhancement, and the anodic stripping voltammetric detection. Among the molecular sieves selected in this study, the performance of SBA-15 was the best probably due to its rather larger pore size. A linear relationship between the anodic stripping peak current and the concentration of cTnI from 0.5 to 5.0 ng/ml and a limit of detection of 0.2 ng/ml were obtained using SBA-15 modified CPE (SBA-MCPE). The established method was tested by determining cTnI in acute myocardial infarction (AMI) samples using enzyme-linked immunoadsorbent assay (ELISA) for comparison analysis, and good results were obtained. _ 2005 Elsevier Inc. All rights reserved.