doi:10.1038/nindia.2016.10 Published online 25 January 2016
Researchers have fabricated a sensitive fluorescent sensor that can detect minute traces of troponin I, a cardiac marker protein that signals the onset of a heart attack1. This sensor is potentially useful for early diagnosis of heart attacks.
Cardiac troponin I (cTnI) regulates the contraction of cardiac muscle. Cardiac muscle cells die during a heart attack, releasing cTnI into the bloodstream. Current techniques for detecting this marker protein are only moderately sensitive and tend to be tedious and expensive.
To develop a fast sensor for detecting cTnI, the researchers synthesized a nanoprobe by attaching cTnI antibodies to modified graphene quantum dots. They then deposited graphene on the nanoprobe and probed its efficiency to detect cTnI.
The nanoprobe emitted blue light when illuminated with ultraviolet light. But graphene on the nanoprobe absorbed the blue light, so that the sensor no longer fluoresced.
On adding cTnI antigen to the sensor, the antigen formed an immune complex by binding to cTnI antibody. This complex detached the graphene from the sensor’s surface, restoring its fluorescence. Such a recovery of fluorescence signals the presence of cTnI.
The sensor’s recovered fluorescence increased with increasing cTnI concentration. It selectively detected cTnI even in the presence of other antigens in human blood serum.
“The sensor could detect cTnI in 10 minutes in clinical samples, retaining 95% of its original sensing efficiency after being stored at 4 degrees Celsius for a year,” says Ashok Kumar, one of the researchers.
The authors of this work are from: CSIR-Central Scientific Instruments Organization, Chandigarh, CSIR-Institute of Genomics and Integrative Biology and Academy of Scientific and Innovative Research (AcSIR), New Delhi, India.
1. Bhatnagar, D. et al. Graphene quantum dots FRET based sensor for early detection of heart attack in human. Biosens. Bioelectron. 79, 495–499 (2016) doi: 10.1016/j.bios.2015.12.083