Diverse metal ions-doped titanium-based metal-organic frameworks as novel bioplatforms for sensitively detecting bisphenol A

Abstract We prepared a series of diverse metal ions-doped titanium-based metal-organic frameworks [Ti-MOFs(M2+), M2+= Co2+, Fe2+, and Ni2+] and used them as novel scaffolds to construct aptasensors that can sensitively determine trace bisphenol A (BPA). Ti-MOF was prepared using 6-(5-carboxypyridin-2-yl) pyridine-3-carboxylic acid as building block, for which different metal ions (Co2+, Fe2+, and Ni2+) were coordinated with N atoms bearing on pyridine of Ti-MOF. The series of Ti-MOFs(M2+) was composed of irregular nanoparticles, Ti clusters and mixed metal valence states of Co2+/Co3+, Fe2+/Fe3+ or Ni2+/Ni3+. A large amounts of BPA-targeted aptamer strands were anchored over the series of Ti-MOFs(M2+) via the combined interaction, such as π-π stacking, hydrogen bond, and metal-N coordination, leading to the excellent sensing ability toward BPA. Among different Ti-MOFs(M2+), the Ti-MOF(Co2+) exhibited a high electrochemical activity and strong stabilization ability for the aptamer-BPA complex. The corresponding aptasensor exhibited an ultra-low detection limit of 0.09 fg mL−1 within the range of 1 fg mL−1 to 1 ng mL−1, along with high selectivity, good stability, and outstanding reproducibility. Further, it demonstrated the extensive serviceability in different environments, including milk, river water, and human serum. The present work shows a promising strategy for analyzing hazardous molecules based on MOF-based aptasensors.