The Signal-Enhanced Label-Free Immunosensor Based on Assembly of Prussian Blue-SiO2 Nanocomposite for Amperometric Measurement of Neuron-Specific Enolase

A signal-enhanced label-free electrochemical immunosensor was constructed by the employment of Prussian blue doped silica dioxide (PB-SiO2) nanocomposite. At first, PB-SiO2 nanocomposite which was produced by using a microemulsion method was used to obtain a nanostructural monolayer on a glassy carbon electrode (GCE) surface. Next amino-functionalized interface were prepared by self-assembling 3-aminopropyltriethoxy silane (APTES) on the PB-SiO2 nanoparticle surface. Then chitosan stabled gold nanoparticle (CS-nanoAu) was subsequently attached, while the entire surface was finally loaded with neuron-specific enolase antibody (anti-NSE) via the adsorption of gold nanoparticle. The sensitivity of the proposed immunosensor has greatly improved as the PB-SiO2 nanostructural sensing film provides plenty of active sites which might catalyze the reduction of H2O2. The immunosensor exhibited good linear behavior in the concentration range from 0.25-5.0 and 5.0-75 ng/mL for the quantitative analysis of neuron-specific enolase (NSE), a putative serum marker of small-cell lung carcinoma (SCLC), with a limit of detection of 0.08 ng/mL. The resulting NSE immunosensor showed high sensitivity and long-term lifetime which can be attributed to the extremely high catalytic activity and biocompatibility of CS-nanoAu/APTES/PB-SiO2 nanostructural multilayers.