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Aptasensor for cardiac biomarker Troponin I using Ferrocene (Fc) –
modified silica nanoparticles
S. Kim1, S. Lee1, H. Jo1 and C. Ban1
1
Department of Chemistry, Pohang University of Science and Technology, Pohang, Gyeongbuk, 790-784, Republic of Korea
Cardiac troponin I (cTnI) is well known as biomarker for early diagnosis of acute myocardial infarction (AMI).
Using the systematic evolution of ligands by exponential enrichment (SELEX) method, we found ssDNA
aptamers against cTnI. The aptamers were selectively bound to both the cTnI and cardiac troponin complexes.
Using surface plasma resonance (SPR), the binding affinities of the cTnI aptamers were measured; the cTnI
aptamers revealed a lower Kd value (270 pM) than the cTnI antibody (20.8 nM). Moreover, we report a new
approach toward designing an electrochemical, label-free aptamer sensor using ferrocene (Fc)-modified silica
nanoparticles as the probe. The developed cTnI aptasensor demonstrated an excellent analytical performance
with a 2.3 pM detection limit (55.2 pg/mL; S/N = 3) and a wide linear detection range (1 – 10,000 pM) in buffer
solution. The specificity of the aptamers was also evaluated using the proposed method; there was no
interference attributed to non-specific binding proteins. Additionally, the cTnI was successfully detected in a
human serum albumin (HSA) solution, and calibration plots were obtained. The cTnI concentrations in mimic
patient samples were determined using a calibration plot. The obtained values were well correlated with the
amounts actually added into the serum. Therefore, the cTnI aptamers and proposed the aptasensor might be
applied instead of an antibody to detect cTnI, providing a new method for diagnosing AMI.