Human cardiac troponin I (cTnI) is a regulatory protein from human heart tissue and is a clinical biomarker in serum for assessing cardiac damage and diagnosing myocardial infarction. Immunoassay measurement of human cTnI in serum is already a useful clinical tool for myocardial infarction; however, a limitation involves the considerable variability between different assays that are marketed by various manufacturers. A viable alternative that holds promise to assay harmonization and true metrological traceability is isotope dilution liquid chromatography mass spectrometry (ID-LC-MS/MS). A well-characterized MS-based reference method for cTnI has not yet been developed since the particular protein is below MS-based limit of detection (LOD) levels.  After myocardial infarction, the concentration levels of cTnI in serum are between 0.5-50�g/L for approximatley 18-24 hours; therefore, effective separation and detection of the troponin protein is challenging due to its extremely low concentration levels.  With the aid of nanomaterials as a platform for immunoaffinity enrichment strategies, low abundant proteins, such as cTnI, can be detected and quantified.  The utility of superparamagnetic iron oxide particles has been recognized in the proteomic field as a favorable candidate for enriching low abundant proteins and peptides for mass spectrometric analysis. Another approach to isolate cTnI from serum is utilizing commercial anodized aluminum oxide (AAO) nanoporous membrane filters. The application of functionalized nanomaterials in biological detection is attractive due to their easy manipulation and large surface areas for maximal antibody binding.   Current efforts to develop an ID-LC-MS/MS reference method with nanomaterial enrichment processes are described.  Magnetic nanoparticles and AAO nanoporous filters are modified and antibodies are immobilized for immunocapture assays. Preliminary studies using anti-peptide antibodies raised in rabbits against known amino acid sequences of proteotypic peptides of cTnI following the SISCAPA (stable isotope standards and capture by antipeptide antibodies) method are also described for enrichment of cTnI.

Role of nanomaterials for the mass spectrometry-based analysis of enriched cardiac troponin I from serum

246th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.