Rapid Blood Test Detects Damaged Cardiac Muscle

A microwave-accelerated and metal-enhanced fluorescence (MA-MEF) technique was used to detect the protein troponin I (TnI), a specific indicator of damage to the heart muscles.

The technique is based on the combined use of low-power microwave heating, silver nanoparticle films (SNFs), and fluorescence spectroscopy for the detection of TnI from human whole blood samples.

The silver nanoparticles were deposited onto amine-modified glass microscope slides by use of Tollen's reaction scheme and characterized by optical absorption spectroscopy and scanning electron microscopy. The detection of TnI from buffer solutions and human whole blood samples on SNFs was carried out by using fluorescence-based immunoassays at room temperature. A control immunoassay, which took two hours total assay time, was compared with the microwave heating MA-MEF–based immunoassay, which took one minute total assay time.

Scientists at Morgan State University (Baltimore, MD, USA) found that the lower limits of detection for TnI from buffer solutions in the control immunoassay and MA-MEF–based immunoassay were 0.1 µg/L and 0.005 µg/L, respectively. However, they were unable to detect TnI in whole blood samples in the control immunoassay owing to the coagulation of whole blood within five minutes of the incubation step. The use of the MA-MEF technique allowed detection of TnI from whole blood samples in one minute with a lower detection limit of 0.05 µg/L.

The authors concluded that the MA-MEF–based immunoassay is one of the fastest reported quantitative detection methods for detection of TnI in human whole blood and has low detection limits similar to those obtained with commercially available immunoassays. Troponins are measured in the blood to differentiate between unstable angina and myocardial infarction in patients with chest pain or acute coronary syndrome. A patient who had suffered from a myocardial infarction would have an area of damaged heart muscle and so would have elevated cardiac troponin levels in the blood. The study was published online on March 11, 2011, in Clinical Chemistry.

Related Links:
Morgan State University