Smartphone-based colorimetric detection of cardiac troponin T via label-free aptasensing

We report an aptasensing platform for the detection of cardiac troponin T (cTnT) in the immediate and early phases of acute myocardial infarction (AMI). High-flow filter paper was used to fabricate a microfluidic paperbased analytical device (mu-PAD), which was further modified with gold-decorated polystyrene microparticles functionalized with a highly specific cTnT aptamer. Herein, cTnT detection is presented in two linear ranges (0.01-0.8 mu g/ml and 6.25-50 mu g/ml) with an LoD of 3.9X10-4 mu g/ml, which is in agreement with reference values determined by the American Heart Association. The proposed platform showed remarkable selectivity against AMI-associated cardiac biomarkers such as TNF-alpha, interleukin-6, cardiac troponin I, and reactive protein-C. This aptasensor is a label-free assay that relies only on smartphone-based image analysis and takes less processing time in comparison with traditional methods like ELISA. Furthermore, it exhibits outstanding stability over 23 days when devices are stored at 4 degrees C. The reported platform is a stable and cost-effective method for the on-site and user-friendly detection of cTnT in normal saline buffer and diluted human serum.

Automated summary

We developed an aptasensing platform for the detection of cTnT in the immediate and early phases of AMI. The platform uses a microfluidic paper-based analytical device modified with gold-decorated polystyrene microparticles functionalized with a highly specific cTnT aptamer. The platform showed high selectivity and stability, and provides a label-free, smartphone-based detection method with shorter processing time compared to traditional methods.