Rational design of Ti3C2 MXene nanocomposite with bromophenol blue for efficient signal amplification: Sensitive electrochemical detection of cardiac troponin I in patient plasma

Today, although a new generation of two-dimensional (2D) MXenes has received considerable interest throughout several fields, the rational design of MXene-based nanocomposites and their particular applications in biosensors remain serious challenges. Herein, to avoid etched-loosely accumulated accordion-like structure of Ti3C2 MXene to restacking, delamination was conducted using bromophenol blue (BPB), which makes the resulting BPB@Ti3C2 nanocomposite as an ideal nanolable for ultrasensitive detection of acute myocardial infarction (AMI) biomarker (cardiac troponin I, cTnI). For this purpose, after sandwiching the cTnI between covalently-bonded Tro4 aptamer on the BPB@Ti3C2 and MNPs/Tro6, the electrocatalytic activity of the nanolabel towards H2O2 was followed as a tracer signal. Owing to i) high effective surface area for immobilization of the Tro4 and ii) large electrocatalytic activity of the BPB@Ti3C2 for electroreduction of H2O2, along with iii) enrichment characteristic of the MNPs/Tro6, as well as iv) the synergistic-assisted signal amplification between the Ti3C2 and BPB, high sensitive detection of cTnI has been introduced. The developed biofunctionalized BPB@Ti3C2 exhibits a wide dynamic range of 200 fg mL−1-250 ng mL−1 with a low detection limit of 20 fg mL−1. The aptasandwich form was used to quantify the cTnI in the human blood plasma of cardiovascular patients, above 90% clinical sensitivity, providing a promising strategy for clinical diagnosis and biochemistry research.