@ARTICLE{Bharti2026-ta,
  title     = "Target-induced shielding layer at the dual-affinity probe
               interface for rapid colorimetric detection of cardiac biomarkers",
  author    = "{Bharti} and Bhardwaj, Priya and Bisht, Bhawana and Bala, Rajni
               and {Sagrika} and Rohit, Manojkumar and Singh, Jagtar and
               Bhalla, Vijayender",
  abstract  = "Cardiac troponin I (cTnI) is a key biomarker for acute
               myocardial infarction (AMI); however, the available detection
               methods are limited by slow responses, complex steps, and costly
               instrumentation, restricting their suitability for rapid or
               point-of-care testing. Herein, we report a rapid and sensitive
               colorimetric assay for the detection of cTnI based on a
               nanoparticle shielding layer and its interfacial interactions
               with an enzyme. To achieve high sensitivity, we employed a
               dual-affinity silver nanoparticle (AgNP) probe coated with two
               highly specific affinity molecules, i.e., aptamer (Apt) and
               antibody (Ab), offering effective detection of the target
               molecule. The affinity layer coating was inherently imperfect,
               leaving exposed regions at the interface of the AgNP probe to
               inhibit the enzyme (urease) by Ag-SH interaction. Upon
               introduction of cTnI, the probe selectively binds to it, and a
               target-induced shielding layer is formed that prevents the
               interaction of the enzyme with the AgNP surface, rendering the
               enzyme active in solution. Consequently, the active enzyme
               generates a colored endpoint for visual detection in <15 min
               with a detection limit of 0.088 ng/mL. We assessed the assay
               performance in a complex matrix to evaluate the stringency. The
               working of the assay was studied using microscale thermophoresis
               (MST), which showed complete masking of the urease-particle
               interaction in the presence of cTnI. Unlike surface-based
               methods, such as ELISA, our solution-phase assay eliminates
               immobilization and blocking steps and achieves enhanced
               sensitivity, representing a paradigm shift in biomarker
               detection.",
  journal   = "ACS Appl. Mater. Interfaces",
  publisher = "American Chemical Society (ACS)",
  volume    =  18,
  number    =  8,
  pages     = "12423--12431",
  month     =  mar,
  year      =  2026,
  keywords  = "cardiac troponin I (cTnI); colorimetric assay; microscale
               thermophoresis (MST); nanoparticle shielding layer; rapid
               detection",
  language  = "en"
}