Unlocking interstitial fluid for acute coronary syndrome diagnosis: ultrasensitive troponin I detection using imprinted polymer nanoparticles

This study presents the first detection of cardiac troponin I (cTnI), a vital biomarker for acute coronary syndrome diagnosis (ACS), in human interstitial fluid (ISF) collected via electroporation. Measurements were performed using molecularly imprinted polymer nanoparticles as synthetic recognition elements and a heat-transfer method within a microfluidic system, yielding results within 15–20 min. This approach demonstrated reliable cTnI quantification across a wide, physiologically relevant concentration range of 0.1 to 1000 pg mL⁻¹ in spiked ISF, achieving an excellent detection limit of 1.85 ± 0.32 pg mL⁻¹. Comparisons with conventional patient sample fluids were conducted by repeating experiments with cTnI-spiked plasma and serum, which exhibited similar detection limits of 1.78 ± 0.28 and 1.80 ± 0.22 pg mL⁻¹, respectively. The developed sensor offers a rapid, highly sensitive, non-invasive, and cost-effective platform for point-of-care ACS diagnosis in ISF, potentially improving patient outcomes and easing healthcare burdens.