| Breast cancer,the leading cause of disability and death among women,overtook lung cancer as the most diagnosed malignancy for the first time in 2020.Early diagnosis of breast cancer is of great significance in reducing the mortality rate and improving the quality of life of patients.Objective The aim of this study is to establish a more sensitive biosensor for the detection of micro RNA-21（miRNA-21）,a biomarker of breast cancer,using a novel conductive nanocomposite material,and to apply the established assay to actual serum samples to provide a methodological basis for early screening of breast cancer.Methods A TH/rGO/CMK-3/AuNPs nanocomposite is composed of thionine（TH）,reduced graphene oxide（r GO）,ordered mesoporous carbon（CMK-3）,and gold nanoparticles（Au NPs）,which help to increase the specific surface area of a glassy carbon electrode（GCE）and to amplify the signal.Meanwhile,methylene blue（MB）was used to mediate a second signal enhancement.Finally,a series of electrochemical performance tests were performed on the constructed miRNA-21 biosensor.Results The current signals of different miRNA-21 concentrations were detected by differential pulse voltammetry（DPV）.The difference between the peak current（IP）measured by miRNA-21 solution and the peak current（I0）measured by blank solution,ΔI value,showed a good linear relationship with the logarithm of miRNA-21 concentration.The curve fitting equation was y（ΔI,μA）=11.31x(lgc[miRNA-21],mol/L)+200.42 with a correlation coefficient R2=0.9981,and the limit of detection（LOD）was calculated to be 0.046 fmol/L.Conclusion The miRNA-21 was detected using this biosensor with a linear range of 10-16mol/L to 10-11mol/L and a LOD of 0.046 fmol/L.A series of methodological validation experiments also proved the good performance of the sensor in all aspects.In addition,real human serum samples were effectively detected using the sensor,indicating its potential for a wide range of applications in early diagnosis. |
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