Electrospun zirconium oxide embedded in graphene-like nanofiber for aptamer-based impedimetric bioassay toward osteopontin determination

An impedimetric bioassay was constructed based on a nanohybrid of zirconium oxide nanoparticles and graphene-like nanofiber (denoted by ZrO2@GNF) for the determination of osteopontin (OPN). A series of ZrO2@GNF nanohybrids with different morphologies and nanostructures were derived from zirconium-based metal-organic frameworks (UiO-66) entrapped within the electric spun polyacrylonitrile (PAN) fiber (represented by UiO-66@PAN) by calcination at different temperatures. The basic characterizations revealed that the UiO-66@PAN nanofibers were collapsed into short nanorods. As such, homogeneously distributed ZrO2 nanoparticles were found to be embedded within the GNF nanostructure. This transition in the chemical structure and nanostructure not only can greatly enhance the electrochemical conductivity of the nanohybrid but also can strengthen the adsorbed bioaffinity toward OPN aptamer strands. As compared with bioassays based on ZrO2@GNF calcined at 500 °C and 900 °C, the ZrO2@GNF nanohybrid obtained at 700 °C (ZrO2@GNF700) demonstrated superior sensing performance, showing a determination limit of 4.76 fg mL−1 within a OPN concentration ranging 0.01 pg mL−1 to 2.0 ng mL−1. It also displayed high selectivity, accompanied by  good reproducibility and stability, acceptable applicability, and excellent repeatability.