Sensors Based On N Protein Aptamer Were Constructed To Detect SARS-CoV-2 And Control Drug Targeted Delivery

The newly identified severe acute respiratory syndrome coronavirus 2（SARS-COV-2）is the last known member of the group of coronaviruses that cause severe respiratory infections in humans.SARS-Co V-2 has four main structural proteins,including Nucleocapsid protein（N protein）,Spike protein（S protein）,Membrane protein（M protein）and Envelope protein（E protein）.The N protein as a major structural protein of coronavirus plays an important role in packaging the RNA genome into helical ribonucleoproteins,modulating host cell metabolism,and regulating viral RNA synthesis during replication and transcription.In this paper,we developed sensors using the advantages of N protein aptamer binding to the target with high affinity and specificity.These sensors was used for high-sensitivity detection of COVID-19 and aptamer-gated release drug targeted treatment for COVID-19.The main research contents are as follows:（1）We report a Regenerable electrochemical N protein aptamer sensor based on complementary DNA as a probe to specifically detect SARS-Co V-2.This electrochemical aptamer sensor was prepared by immobilizing the double-stranded DNA hybrid obtained by hybridizing the N protein aptamer with complementary DNA labeled with Fc on the surface of gold electrode.After incubating with the target,the aptamer-target complex is separated from the labeled ds-DNA hybrid and preferentially binds to the N protein in the solution.The concentration of N protein was measured by detecting the change in electrochemical signal caused by the conformational transition of the c DNA remaining on the electrode surface.This sensor has a linear relationship between the N protein concentration of 10 f M-100 n M(ΔIp=0.098 log C_{N protein}/f M-0.08433,R²=0.99),and the detection limit is 1 f M（S/N=3）.This electrochemical aptamer sensor has been used to test the spiked detection of throat swabs and blood samples of three volunteers.It is expected to realize sensitive detection of N protein in complex real samples to help early detection of COVID-19 patients.（2）Aptamer-based gated mesoporous silica nanoparticles for targeting and controlling drug delivery.Remdesivir is a nucleoside analogue with antiviral activity.We constructed an aptamer gated mesoporous silica nanoparticle sensor to control the targeted delivery and release of remdesivir.In this paper,the aptamer sensor was constructed by combining the advantages of mesoporous silica material and N protein aptamer with high affinity.In this sensor,the N protein and its partial complementary DNA strands were hybridized into double strands DNA and the combination with gold nanoparticles was fixed on the surface of mesoporous silica microspheres.In the presence of N protein,the formation of the N protein-aptamer complex carries gold nanoparticles off the surface of the microsphere,thus enabling the targeted release of remdesivir.Therefore,this sensor was expected to achieve clinical application in targeted therapy of COVID-19 patients.