Analytical Sciences

A Label-free Cardiac Troponin T Electrochemiluminescence Immunosensor Enhanced by Graphene Nanoplatelets

Nura Fazira NOOR AZAM,* Nur Afina MOHAMMAD,* Syazana Abdullah LIM,** and Minhaz Uddin AHMED*

*Biosensors and Biotechnology Laboratory, Chemical Science Programme, Faculty of Science Universiti Brunei Darussalam, Jalan Tungku Link, Gadong BE1410, Brunei Darussalam
**School of Applied Sciences and Mathematics, Universiti Teknologi Brunei, Jalan Tungku Link, Gadong BE1410, Brunei Darussalam

In this study, a direct and label-free immunosensor was designed and constructed by modifying the screen-printed electrode with graphene nanoplatelets (GNPs) for the detection of the cardiac troponin T (cTnT). Firstly, GNPs were drop-casted onto carbon working electrode. Monoclonal cTnT antibodies were then immobilized on the GNPs via physical adsorption; finally, BSA was introduced to block non-specific binding sites. The detection of cTnT was performed using an electrochemiluminescence (ECL) technique with tris(bipyridine)ruthenium(II) chloride ([Ru(bpy)₃]Cl₂) used as a luminophore and TPrA (tripropylamine) as a co-reactant. The ECL intensity was demonstrated to be directly proportional to the cTnT concentration where a linear range from 100 pg mL⁻¹ to 5 fg mL⁻¹ of the cTnT detection was established. An extremely low limit of detection was achieved to be 0.05 fg mL⁻¹ with an outstanding specificity. Additionally, this immunosensor showed excellent percentage recovery for real samples analyses in artificially spiked human serum.

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