Construction of well-ordered electrochemiluminescence sensing interface using peptide-based specific antibody immobilizer and N-(aminobutyl)-N-(ethylisoluminol) functionalized ferritin as signal indicator for procalcitonin analysis.

With the aim of providing a powerful analytical tool for early diagnostics of procalcitonin (PCT), an ultrasensitive electrochemiluminescence (ECL) biosensor was developed based on a 3D well-ordered sensing interface and biocompatible signal indicator. Polyaniline nanorod arrays grafted reduced graphene oxide (PANI NRs/rGO) was hybridized with gold nanoparticles (PANI NRs/rGO-Au) as sensing substrate. To improve the specificity, HWRGWVC heptapeptide (HWR) as specific capture-antibody (Ab1) immobilizer was introduced to construct a PANI NRs/rGO-Au-HWR sensing interface. Due to their synergistic effect, the proposed interface improved the incubation efficiency of antibody on substrate with faster electron-transfer for remarkable ECL enhancement. Then, ferritin (Ft) with superiority of biocompatibility was utilized to crosslink with ECL luminophore of N-(aminobutyl)-N-(ethylisoluminol) (ABEI-Ft) as signal indicator. ABEI-Ft exhibited high ECL efficiency and could capture detection-antibody (Ab2) via amine reaction. Due to the enzyme-mimic property of ferric nanocore inside of Ft, abundant reactive oxygen species (ROSs) were produced in the presence of hydrogen peroxide, which further enhanced the ECL signals. On the basis, a novel biosensor was developed using PANI NRs/rGO-Au-HWR as specific sensing interface and ABEI-Ft as signal label, which performed sensitive response to PCT concentration with a wide linear range of 100 fg/mL- 50 ng/mL and a detection limit of 54 fg/mL.