SERS biosensor based on the Cas13a assisted entropy-driven system and lychee-like Fe–TiO2 with excellent exciton capture and separation

Background Entropy-Driven Circuits (EDC), distinguished by their spontaneous operation and absence of enzymatic reactions, represent a superior strategy for integration with CRISPR/Cas systems, as they obviate the potential for interference among various enzymes during the process of DNA amplification and CRISPR/Cas system integration. Due to the wide band gap of TiO 2 , its response to visible light is limited, and owing to its high crystallinity and exceptionally stable crystal lattice, the charge transfer (CT) process in TiO 2 is suboptimal. Results In this study, lychee-like Fe–TiO 2 was firstly prepared to serve as Raman enhanced substrate, facilitating exciton capture and separation to exhibit an excellent Surface-enhanced Raman spectroscopy (SERS) performance. It is proven that the incorporation of Fe results in a significantly narrower band gap for TiO 2 , facilitating exciton resonance. The amount of Fe in TiO 2 was optimized to fabricate a SERS biosensor for detection of miRNA-21 based on the Cas13a assisted entropy-driven system. The detection limit of miRNA was 43.88 fmol/L. Significance This work proposes a sensing strategy that integrates the CRISPR/Cas system with EDC, leveraging a semiconductor substrate exhibiting superior SERS performance to provide a stable Raman signal, thereby enabling highly sensitive detection of miRNA-21, which has a potential application in disease early warning and treatment.