Atomic Layer Deposition-Derived MoS/NbS Nanoheterojunctions Enable High-Density Quantum Dot Loading for Enhanced Signal-On Photoelectrochemical Detection of cTnI.

Acute myocardial infarction (MI) remains a major global health threat, necessitating rapid and sensitive detection strategies. Herein, we report a signal-on quantum dot photoelectrochemical (QD-PEC) biosensor for ultrasensitive detection of cardiac troponin I (cTnI), based on a MoS/NbS nanoheterojunction constructed via atomic layer deposition (ALD). The petal-like MoS/NbS, uniformly grown with atomic precision, offers a high surface area and efficient charge transport, serving as an ideal scaffold for dense CdTe QD loading. The strong interfacial coupling between MoS/NbS and CdTe QDs enhances photogenerated charge separation and suppresses recombination, yielding significantly improved photocurrent response. Comprehensive structural, optical, and electrochemical characterizations confirm the integrity and superior photoactivity of the heterostructure. The resulting PEC biosensor exhibits a broad linear detection range (10 to 10 M) and an ultralow detection limit of 6 × 10 M for cTnI, along with excellent stability and selectivity, offering a promising platform for early MI diagnosis.