Prussian Blue-functionalized ceria nanoparticles as label for ultrasensitive detection of tumor necrosis factor-α

Ultrasensitive electrochemical immunosensor for the detection of tumor necrosis factor-α (TNF-α) was reported based on Prussian Blue (PB) functionalized ceria nanoparticles (PB-CeO2) as label. To prepare PB-CeO2, CeO2 was first coated with a positively charged chitosan (CS) layer to adsorb negatively charged Fe(CN)63−. Then, with the addition of FeCl2, PB nanoparticles were synthesized within the CS layer on the CeO2 surface. The synthesized PB-CeO2 was found to have high sensitivity toward H2O2 detection. Secondary anti-TNF-α antibody (Ab2) was cross-linked to the PB-CeO2 through glutaraldehyde to obtain the label (PB-CeO2-Ab2). The electrochemical immunosensor for the detection of TNF-α was constructed based on the traditional sandwich structure with the immobilization of primary anti-TNF-α antibody (Ab1) onto gold nanoparticles (AuNPs) modified carbon nanotube (CNT) surface. With the response of the immunosensor toward 1 mM H2O2 as signal, the proposed immunosensor has wide linear range (0.005–5 ng/mL) and low detection limit (2 pg/mL) to TNF-α. The proposed immunosensor preparation strategy successfully demonstrated a simple, sensitive and specific method that can be expanded to the detection of other proteins.