Thermometer-Like Device Could Help Diagnose Heart Attacks

A solution of antibody-functionalized platinum (Pt) nanoparticles was added to of TnI-spiked human serum. After incubation for 10 minutes at room temperature with gentle shaking, the sample containing TnI–Pt complexes was added to a gastight glass vial whose inner surfaces were coated with TnI antibodies.

The captured TnI was conjugated to the inner surface of a glass vial, to which a hydrogen peroxide (H2O2) solution was added. After the glass vial was sealed with a screw cap containing a silicon septum, a capillary tube containing a drop of ink was inserted through the septum. The catalytic dissociation of H2O2 to water and oxygen increased the pressure inside the glass vial and raised the ink level in the capillary tube. The ink level increased with the platinum nanoparticle concentration, which is proportional to the TnI concentration. The sensitivity of this assay for TnI in human serum after a five minute dissociation reaction, detected with the naked eye, was 0.1 ng/mL, which was better than the sensitivity of the conventional colorimetric method using the 3,5,3',5'-Tetramethylbenzidine (TMB) oxidation reaction under the same conditions.

The authors concluded that they had successfully developed an adroit method for the detection of TnI in human serum using antibody-functionalized dendritic platinum nanoparticles and a capillary tube containing a drop of ink. The pressure increase caused by the catalytic dissociation of H2O2 by platinum nanoparticles induces an increase in ink level, which is easily identified with the naked eye. Because the ink level increases further with reaction time, the limit of detection could be improved by increasing the reaction time. This simple and cost-effective method may be especially beneficial for people in underdeveloped countries. The study was published on April 20, 2015, in the journal Analytical Chemistry.

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