A Signal Amplification Strategy of CuPtRh CNB-Embedded Ammoniated Ti <subscript>3</subscript> C <subscript>2</subscript> MXene for Detecting Cardiac Troponin I by a Sandwich-Type Electrochemical Immunosensor.

An early diagnosis of cardiovascular disease is of great importance to patients. Herein, a sandwich-type immunosensor for the detection of cardiac troponin I (cTnI) is prepared by using gold nanoparticles (Au NPs) and a composite (CuPtRh CNBs/NH 2 -Ti 3 C 2 ) of trimetallic hollow CuPtRh cubic nanobox (CNB)-embedded few-layer ultrathin ammoniated MXene (NH 2 -Ti 3 C 2 ). The embedding of the CuPtRh CNBs into NH 2 -Ti 3 C 2 successfully prevents the restacking of NH 2 -Ti 3 C 2 and offers more active sites for catalytic H 2 O 2 reduction, which can effectively increase the current signal of the immunosensor. The designed sandwich-type electrochemical immunosensor for detection cTnI has a detection range of 25 fg mL -1 to 100 ng mL -1 , and the detection limit is 8.3 fg mL -1 (S/N = 3). Moreover, the immunosensor also demonstrates high sensitivity, acceptable reproducibility, and good stability. More importantly, the designed system offers a direction for early clinical testing of cardiovascular and cerebrovascular diseases.