To prepare an electrochemical immunosensor based on carboxylated multi-walled carbon nanotubes(CMWCNTs)and Ag nanoparticles@zeolite imidazolate framework—8(AgNPs@ZIF—8)for the detection of nuclear matrix protein 22(NMP22)in urine.CMWCNTs and AgNPs@ZIF—8 are drop-coated onto a glassy carbon electrode(GCE)

which is able to specifically recognize NMP22 by binding the NMP22 antibody through the Ag-N bonds

and the quantitative detection of NMP22 is achieved by differential pulse voltammetry(D

PV).There is a linear relationship between the current change Δ

I

of DPV and the logarithmic value of NMP22 concentration(lg

C

)in the range of 0.1~10

5

pg/mL(

R

2

=0.996)

and the limit of detection is 0.0094pg/mL

with spiked recoveries ranging of 99.26%~104.7%.The content of NMP22 in the bladder cancer group is significantly higher than that in the control group(

P

<

0.01)

and the area under curve of receiver operating characteristic(ROC)is 0.930.The sensor demonstrates excellent selectivity

reproducibility

and stability

and is successfully applied to the sensitive and accurate detection of NMP22 in urine samples

which provides a new method for the early screening of bladder cancer.