Photo-Nanozyme-Integrated Photoelectrochemical-Electrochemical Dual-Mode Biosensor: Enabling Amplification-Free Detection of miRNA-133a in Acute Myocardial Infarction

Acute myocardial infarction (AMI) is a leading cause of death and disability worldwide. MicroRNA-133a (miRNA-133a) serves as a valuable biomarker for AMI, offering specificity and stability for an early diagnosis. However, existing miRNA biosensors faced challenges in detecting low concentrations, ensuring accuracy, and maintaining immunity to interference. This study presents a novel 1<i>D</i>/2D bismuth vanadium oxide (BiVO₄) and copper-tetraphenylporphyrin (Cu-TCPP) metal-organic framework heterojunction, constructed via a simple electrodeposition method, which enabled the development of an amplification-free photoelectrochemical/electrochemical (PEC-EC) dual-mode sensor. The S-type heterojunction formed between Cu-TCPP and BiVO₄ significantly improved the separation efficiency of the photogenerated carriers. Furthermore, the peroxidase-like catalytic activity of Cu-TCPP facilitated signal amplification through a photonanozyme mechanism. Experimental results demonstrated that the sensor achieved high sensitivity with extremely low detection limits as low as 0.003 fM for PEC and 0.02 fM for EC, along with excellent selectivity, stability, and reproducibility. This study provides an efficient detection platform for miRNA-133a, highlighting its potential for early diagnosis and monitoring of diseases linked to miRNA biomarkers.