Ultrasensitive photoelectrochemical detection of cancer markers based on heterojunctions constructed from Bi₂O₃ star-like flower nanoclusters and CdS hollow nanorods

CYFRA21-1 is a tumor marker for lung cancer, and its rapid and accurate detection can provide evidence for the early diagnosis of lung cancer. In this work, Bi-Fe turnbull blue analogues (Bi-Fe-TBA) were synthesized by the self-templating method. Bi₂O₃-SFNs was prepared by simple oxidation in air using Bi-Fe-TBA as a template. Bi₂O₃ Star-like Flower Nanoclusters (Bi₂O₃-SFNs) and CdS Hollow Nanorods (CdS-HNRs) were used to form a unique type II heterojunction for the first time. The arrangement of energy levels between CdS-HNRs and Bi₂O₃-SFNs, along with their hollow structure and star shape, effectively suppressed the recombination of photogenerated electrons and holes while shortening carrier transport distance. An ultra-sensitive PEC biosensor was developed to detect the lung cancer marker CYFRA21-1, leveraging the superior photoelectric conversion capabilities of Bi₂O₃-SFNs/CdS-HNRs. The sensor demonstrates outstanding stability, specificity, reproducibility as well as a wide linear range (10^-4 - 10 ng mL^-1) and low detection limit (4.23 × 10^-5 ng mL^-1). This study is valuable for the preparation of other functional materials using TBA as a template.