An efficient electrochemical immunosensor for Alpha-Fetoprotein detection based on the CoFe prussian blue analog combined PdAg hybrid nanodendrites.

A sandwich-type electrochemical immunosensor was developed using PdAg nanodendrites modified CoFe prussian blue analog (PdAg NDs/CoFe PBA) as the signal label for the alpha-fetoprotein (AFP) detection. The novel hollow porous CoFe PBA with KCoFe phase was synthesized via self-template epitaxial growth strategy. Benefiting from the filling of K ions and the hollow porous structure, the electron transfer rate and the mass transfer rate of CoFe PBA were improved, further enhancing the catalytic capacity. In addition, the special dendritic morphology of PdAg NDs can maximize the proportion of catalytic active sites, and stable Pd-N and Ag-N bonds can further fix more immune molecules to increase the sensitivity of electrochemical immunosensors. Under optimized parameters, the fabricated immunosensor demonstrated a wide linear range detection from 100.0 fg mL-1 to 200.0 ng mL-1, and a low detection limit of 18.6 fg mL-1. Simultaneously, the immunosensor with acceptable reproducibility, specificity, stability and exhibited satisfactory performance in human serum analysis. This work provides a new line for the detection of other tumor markers, which means that it has great application potential in immune analysis.

The effects of verbal instruction on affective and expectancy learning.

The current research assessed the effects of verbal instruction on affective and expectancy learning during repeated contingency reversals (Experiment 1) and during extinction (Experiment 2) in a picture-picture paradigm. Affective and expectancy learning displayed contingency reversal and extinction, but changes were slower for affective learning. Instructions facilitated reversal and extinction of expectancy learning but did not impact on affective learning. These findings suggest a differential susceptibility of affective and expectancy learning to verbal instruction and question previous reports that verbal instructions can accelerate the extinction of non-prepared fear learning in humans.