Construction Of Three-dimensional DNA Walker Based On Interparticle Interaction And Its Detection Application

DNA walkers are a unique class DNA molecular machine,which possesses the merit of distinctive mechanical movement,high directionality and intrinsic signal amplification capability.Due to the limited one-dimensional(1-D)or two-dimensional(2-D)walking space and the low flux of substrate DNA in nanostructures,the three-dimensional(3-D)DNA walker subsequently reported overcomes these shortcomings.Among them,three-dimensional(3-D)DNA walkers can walk more steps due to high DNA loading capacity of micro or nanoparticles,and its operation is usually based on the movement of a walking strand immobilized on track strand-functionalized particles or a free walking strand along the particle surface.Such 3-D DNA walkers may be confronted with deficiencies of the limited walking area or liable derailment that weakens signal accumulation,which will futher affect their application in analytical determinations.On the basis of above analysis,an interparticle relatively motional DNA walker is constructed,and its detection application is further realized.This thesis is divided into two chapters:Chapter one is the introduction section,which mainly summarizes DNA molecule,DNA molecular machine and DNA walker.This paper mainly introduces the research status of 3-D DNA walker,including its characteristics,classification and application progress,and introduces the main scientific problems and research contents of this thesis.In chapter two,we focus on the design of a DNA walker with relative motion between particles,and further realize the sensitive detection of Zika virus specific RNA fragment.The DNA walker consists of walking particles(WPs)and orbital particles(TPs).The walker is composed of walking particles(WPs)and track particles(TPs).Triggered by the target that specifically unlocks the walking strand,the liberated walking strands on WP cooperatively hybridize with the track strands.Through DNAzyme-induced hydrolysis of ribonucleotides,the track strand gets cleaved by the DNAzyme,accompanying by the fluorophore release.The released walking strand on WP then hybridizes to the next track strand,inducing the relative motion between the WP and the surrounding TPs.Through the continuous interaction of WP with surrounding TPs,a copious of fluorophores and a large signal accumulation is generated.The DNA walker shows high sensitivity and good specificity for the analysis of targets,and can reliably detect the target in complex matrix with good recovery.The constructed DNA walker provides a new type of free and robust motion mode between particles and holds potential in real sample detection.