Unlocking Interstitial Fluid for Acute Coronary Syndrome Diagnosis: Ultrasensitive Troponin I Detection Using Imprinted Polymer Nanoparticles

Abstract

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), which was collected using 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 0.41 ± 0.06 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 0.45 ± 0.01 and 0.49 ± 0.04 pg mL -1 , respectively. The developed sensor offers a rapid, highly sensitive, non-invasive, and costeffective platform for point-of-care ACS diagnosis in ISF, potentially improving patient outcomes and easing healthcare burdens.