Surface Functionalization and Reversible Disassembly of DNA-Assembly Nanoparticles for Sensitive and Multiplexed Detection of DNA Targets Without Enzymatic and Catalytic Amplification

Recently, DNA-assembly nanoparticles based on DNA-metalion interactionsare emerging as new building blocks for drug delivery and metal nanostructuresynthesis. However, the surface modification of DNA-assembly nanoparticlesusing functional biomolecules that can identify specific targets hasrarely been explored. In this study, we developed a new immobilizationchemical strategy to efficiently functionalize the barcode DNA-assemblynanoparticles (bcDNA NPs) with thiolated probe DNA (pDNA) for synthesizingpDNA-functionalized bcDNA NPs (pDNA-bcDNA NPs). We used them as nanoprobesto successfully demonstrate the sensitive and selective detectionof multiple DNA targets. Importantly, Au ions played an essentialrole as anchoring sites via their conjugation with both thiolatedpDNA and bcDNA NPs. In addition, we could reversibly and rapidly disassemblethe pDNA-bcDNA NPs into the initial bcDNA strands with a recoveryrate of 91%; this process significantly amplified the signal by releasinga million bcDNA strands, which enabled DNA quantification from a singlepDNA-bcDNA NP. The Au3+ concentration, pH, and surfacepassivation conditions were carefully investigated to maximize thepDNA loading to 8500 strands/bcDNA NP. The limit of detection wasdetermined to be 221 fM, which is the most sensitive among the absorbance-basedmethods without polymerase chain reaction, hybridization chain reactions,catalytic hairpin assembly, and other reactions involving enzymesand catalysts. The reversible disassembly of DNA strands and Au ion-mediatedconjugation chemistry could be extended for the detection of othertypes of targets, such as proteins, metal ions, and small molecules,using other organic functionalities that are or can be thiolated,including polypeptides, aptamers, and antibodies.

Automated summary

Recently, DNA-assembly nanoparticles based on DNA-metalion interactions have been developed for drug delivery and metal nanostructure synthesis. In this study, a new chemical strategy was developed to functionalize DNA-assembly nanoparticles with thiolated probe DNA, leading to the successful detection of multiple DNA targets.