Studies on the interactions of Ag(i) with DNA and their implication on the DNA-templated synthesis of silver nanoclusters and on the interaction with complementary DNA and RNA sequences.

Alejandra De La Hoz,Raimundo Gargallo,Alba Navarro,Anna Aviñó,Ramon Eritja

doi:10.1039/d1ra00194a

Abstract

Silver nanoclusters (AgNCs) prepared by the reduction of silver ions in the presence of DNA oligonucleotides have attracted great interest as potential diagnostic tools for their tunable and high fluorescent properties. In this work, three DNA sequences that consist of a 12-nucleotide long probe sequence at the 5′-end linked to the complementary sequence to three miRNAs are studied. First, the interaction of these sequences with Ag(i) was characterized by means of circular dichroism spectroscopy. By applying multivariate methods to the analysis of spectroscopic data, two complexes with different Ag(i) : DNA ratios were resolved. Secondly, the impact of several experimental variables, such as temperature, borohydride concentration and reaction time, on the formation of AgNCs templated by these three sequences was studied. Finally, the fluorescence properties of the duplexes formed by DNA probes with complementary DNA or miRNA sequences were studied. The results presented here highlight the role of the secondary structure adopted by the DNA probe on the fluorescence properties of DNA-stabilized AgNCs which, in turn, affect the development of methods for miRNA detection.

Highlights

Metal nanoclusters (NCs) are one of the most important contributions to nanotechnology to nanomedicine due to their excellent physical and chemical properties.[1]
DNA-stabilized AgNCs were synthesized using the procedures described in the literature.[27]
We studied the fundamental aspects of AgNC synthesis and the key variables that affect the analytical signal

Summary

Introduction

Metal nanoclusters (NCs) are one of the most important contributions to nanotechnology to nanomedicine due to their excellent physical and chemical properties.[1] NCs are tiny (less than 2 nm) groups of a few metal atoms that have quantized molecule-like orbitals, enabling the existence of spectroscopic phenomena, such as uorescence.[2,3] Extensive and critical reviews on this topic have been published.[4,5,6] Speci cally, silver nanoclusters (AgNCs) prepared by the reduction of silver ions in the presence of short DNA oligonucleotides have attracted great interest as potential diagnostic tools for their tunable and highly uorescent properties.[7] Recently, the use of RNA nanorings to encapsulate AgNCs has been described.[8] studies have been conducted to try to correlate DNA sequences and lengths with the uorescence properties of AgNCs,[9] the signi cance of the secondary structures of the DNA templates on the emission properties of the resulting AgNCs is still a matter of research.[10,11,12,13,14,15,16]

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