Sequence-Modulated Interactions Between Single Multivalent DNA-Conjugated Gold Nanoparticles

In recent years,with the development of science and technology,DNA-conjugated gold nanoparticles(AuNPs)have become versatile tools for broad applications from biochemical analysis to materials science.Specially,programmable self-assembly using DNA-conjugated AuNPs as a component shows great hopes for building complex plasma nanomaterials in multiple sizes.For these nano structured materials,the assembly process and properties usually depend on the interaction of the polyvalent DNA-AuNPs nanoconjugates,but the polyvalent conjugates of the nanomaterials,the dynamic interaction of the assembly process,and the properties of the assembly structure are still incompletely revealed.Therefore,on the basis of our previous work,we mainly carried out the following work:In the second chapter,we studied the interaction of multivalent DNA-AuNPs with different DNA sequences using a single DNA-AuNPs nanoconjugates as a probe.We achieved in-situ real-time observation of the interaction procession of completely mismatched,fully matched and single-base mismatched polyvalent DNA-AuNPs with each other.According to the change of the color and light intensity of the nanoconjugates,the nonspecific adsorption and specific binding can be distinguished,and the effective collision and non-effective collision can be also distinguished.Moreover,the multivalent interaction process of the fully matched DNA-AuNPs and the multivalent interaction process of DNA-AuNPs containing base mismatches is irreversible and reversible,respectively,which can be used to distinguish whether the existence of the base mismatch or not.In the third chapter,we studied the kinetics of the binding of single DNA-AuNPs nanoconjugates.Based on the plasma coupling effect of gold nanoparticles,the binding kinetic process of DNA-AuNPs nanoconjugates was observed by dark field microscopy and UV-visible spectroscopy.By adjusting the length of DNA sequence and the content of GC,the quantitative correlation between the apparent binding rate constant with sequence length and GC content allows us to predict the apparent binding rate constant,which plays an important role in the selection of appropriate chain sequences for constructing programmable nanomaterials with DNA-AuNPs.In the fourth chapter,we investigated the kinetics of the dissociation process of DNA-AuNPs nanoconjugates containing single base mismatches.The dissociation kinetics of single nanoconjugates containing monobasic mismatched DNA-AuNPs was monitored in real time by dark-field microscopy single-particle imaging.It was found that the irreversibility of multivalent DNA-AuNPs interaction can be adjusted by base mismatch,and the change of the hybridization state of DNA-AuNPs complex can be adjusted by changing the base mismatch position in DNA strand,and the quantitative correlation of the base mismatch site and the kinetics of dissociation can be obtained.This can be used as a method of identifying single base mismatches and also makes it possible for fabricating active plasmonic nanomaterials with controlled dynamic properties.