科研之友
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摘要
Development of nucleic acids containing unnatural moietieshasexpanded the scope of genetic materials, and modifications of nucleobaseshave been extensively explored and found broad applications. However,previous efforts have mainly focused on modifying nucleobases withsmall molecules, while nucleobase modification with macromoleculeshas barely been explored. In this work, we first demonstrated theconstruction of highly programmable bottlebrush-like DNA structuresby enzymatic production of DNA containing nucleobases modified withcoupling handles and chemical attachment of single-stranded DNAs ontothese handles. Employing these bottlebrush DNAs (BDs), we then developeda method named bottlebrush DNA-primed rolling circle amplification(BDP-RCA), which could rapidly produce branched DNA products withultrahigh molecular weights in a controllable manner. BDP-RCA generatedup to approximately 20-fold more products than ordinary RCA within10 min. Moreover, the BDP-RCA product demonstrated a netlike structurein aqueous solution and a structure consisted of uniformly sized nanoflowerswith a diameter of approximately 0.7 & mu;m when lyophilized. Theseobservations suggested the great potential of BDP-RCA in the developmentof materials and methods for biosensing, which were demonstrated withseveral examples. First, ultrasensitive detection of human & alpha;-thrombinwith a limit of detection (LOD) of 1.1 pM was achieved by using BDP-RCAto amplify the detection signal in an ELISA-like assay. Second, magneticbeads immobilizing the BDP-RCA product were successfully applied forthe efficient capture, enrichment, and preservation of a protein orbacterial cells to be detected. The LOD for the detection of human & alpha;-thrombin with this method was 68.5 pM.
