DNA Sensor Based On SiNW-Array FET For Biomedical Detection

Circulating tumorDNA(ctDNA)is a"real-time"biomarker for non-invasive evaluation of cancer,which has important value in tumor diagnosis,prognosis and targeted therapy.The existing ctDNA detection methods have certain limitations:1)High-sensitivity detection requires high-precision instruments and complex process steps;2)The signal conversion process is vulnerable to the interference of environmental noise,resulting in unstable signal detection;3)Biometric signals are weak and cannot be processed effectively and read accurately.Therefore,in order to solve the above problems,a biosensor based on Silicon Nanowire array Field Effect Transistor(SiNWs-array FET)to detect tumor marker ctDNA was studied in this paper.The main research contents and results of this paper were as follows:1.Performance characterization of SiNWs-array FET sensor.The morphology,transmission characteristics and pH detection characterization of the prepared SiNWs-array FET sensor were firstly characterized by scanning electron microscopy,metallographic microscopy and sourcemeter.The results showed that the sensor had good transmission characteristics and pH detection characteristics in the liquid environment,which laid a foundation for subsequent detection of ctDNA in the liquid phase environment.2.A SiNWs-array FET biosensor was set up.To realize the tumor markers ctDNA ultrasensitive detection,we prepared a polydimethylsiloxane(PDMS)reaction chamber and built a SiNWs-array FET biosensor via 3-aminopropyltriethoxysilane(APTES).The results showed that the SiNW array biosensor could sensitively detect as low as 10 aM ctDNA,and had a good linear relationship between the concentration of 1×10^-16 to 1×10^-11 M.In addition,the sensor had good specificity,stability and reproducibility,which provided a new and effective method for ctDNA detection.3.The SiNW-array FET signal amplification biosensor based on gold nanoparticles(AuNPs)and rolling circle amplification(RCA)was established.To achieve first-order signal amplification,the concentration of probe and phosphate buffer was firstly optimized,then AuNPs/signal probe complex was synthesized.RCA further improved the signal-to-noise ratio of the sensor and achieve secondary signal amplification via the catalysis of phi29DNA polymerase.The results showed that the SNR of 10 aM ctDNA could reach 10.69 dB after secondary amplification.In addition,the sensor had been demonstrated to have good specificity,providing a new signal amplification method for future in vitro cancer diagnostic analysis and postoperative treatment.In summary,to realize high sensitivity detection of ctDNA detection,two kinds ofDNA sensors for biomedical detection based on SiNW-array were studied in this paper.The experimental data show that the two kinds ofDNA sensors have good sensitivity and specificity,which can provide a new method for cancer detection in the future.