An Optical Biosensor Based on Few-Layer MoS2 Nanosheets for Sensitive Detection of Tumor Marker ctDNA
Cancer has become one of the major diseases threatening human health and life.Circulating tumor DNA(ctDNA)testing,as a practical liquid biopsy technique,is a promising method for cancer diagnosis,targeted therapy and prognosis.In this work,an optical biosensor based on few-layer MoS2 nanosheets was studied for the highly sensitive detection of tumor marker ctDNA.Firstly,The few-layer MoS2 nanosheets were prepared by shear exfoliation method,and the preparation conditions were optimized to prepare the few-layer MoS2 nanosheets with large transverse size and uniform thickness.Secondly,the accelerated aggregation and precipitation behavior of MoS2 nanosheets in high concentration salt solution was studied by detecting the absorbance change of dispersion.Then,based on the adsorption capacity of MoS2 nanosheets on single-stranded DNA,the inhibition effect of single-stranded DNA on salt-induced precipitation of few-layer MoS2 nanosheets was studied.Finally,the optical biosensor was constructed by using the change of absorbance of dispersion caused by the fall off of double-stranded DNA formed by hybridization from the few-layer MoS2 nanosheets,and the performance of the sensor was tested by hybridizing cpDNA with different concentrations of ctDNA.Results showed that the absorbance of ctDNA in the concentration range of 25 nM-100 nM was inversely linear with the dispersion of MoS2 nanosheets when cpDNA concentration was 100 nM.The linear regression equations between the absorbance of the dispersion of few-layer MoS2 nanosheets and the ctDNA concentration at wavelengths of 401 nm and 448 nm were Y=0.235 57-0.000 70X,R2=0.942 22 and Y=0.212 53-0.000 50X,R2=0.951 41,respectively.This study demonstrated that the optical biosensor was able to detect tumor marker ctDNA and provided an effective sensing strategy for future in vitro cancer detection and diagnosis.
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