Sandwich-type electrochemical aptasensor based on hollow mesoporous carbon spheres loaded with porous dendritic Pd@Pt nanoparticles as signal amplifier for ultrasensitive detection of cardiac troponin I.

Signal amplification is crucial to improve the sensitivity for the electrochemical detection of cardiac troponin I (cTnI), one of the ideal biomarkers for early acute myocardial infarction (AMI) diagnosis. Herein, we developed a novel signal amplification strategy to construct a sandwich-type electrochemical aptasensor for the detection of cTnI. Core-shell Pd@Pt dendritic bimetallic nanoparticles loaded on melamine modified hollow mesoporous carbon spheres (Pd@Pt DNs/NH 2 -HMCS) was prepared as labels to conjugate with thiol-modification DNA aptamers probe for signal amplification. While introducing numerous amino groups, the melamine functionalized hollow mesoporous carbon spheres (NH 2 -HMCS) retained the edge-plane-like defective sites for the adhesion and electrocatalytic reduction of H 2 O 2. With the unique characteristics of NH 2 -HMCS, it not only enhanced the dispersity and loading capacity of core-shell Pd@Pt dendritic bimetallic nanoparticles (Pd@Pt DNs), but also improved the stability of bonding by the affinity interaction between Pd@Pt DNs and amino groups of melamine. Meanwhile, the synergistic catalysis effect between Pd@Pt DNs and NH 2 -HMCS significantly enhanced the electrocatalytic reduction of H 2 O 2 and further amplified the signal. Under optimal conditions, this recommended aptasensor for cTnI detection displayed a wide dynamic range from 0.1 pg/mL to 100.0 ng/mL and a low detection limit of 15.4 fg/mL (S/N = 3). The sensor also successfully realized the analysis of cTnI-spiked human serum samples, meaning potential applications in AMI diagnosis. [Display omitted] • A facile strategy for preparing melamine-modified carbon materials as superb support matrix was presented. • Based on the strategy, amino groups-enriched NH 2 -HMCS retained its advantages of morphology characteristics. • Pd@Pt DNs/NH 2 -HMCS as a signal amplification label showed excellent electrocatalytic performance for the reduction of H 2 O 2. • A novel sandwich-type electrochemical aptasensor was designed for detecting cTnI. • The sensitive aptasensor possessed a wide dynamic range and low detection limit for detecting cTnI. [ABSTRACT FROM AUTHOR]