Structural Influence on the Post-Clustering Stability of DNA/AgNCs Fluorescence.

Riddhi Nagda,Sooyeon Park,Seong Wook Yang,Chang Seop Lee,Pratik Shah

doi:10.3390/nano9050667

Riddhi Nagda, Sooyeon Park + Show 3 more

Open Access

https://doi.org/10.3390/nano9050667

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Journal: Nanomaterials	Publication Date: Apr 28, 2019
Citations: 9	License type: CC BY 4.0

Affiliation: Yonsei University, University of Copenhagen

Abstract

DNA-encapsulated Silver Nanoclusters (DNA/AgNCs) based sensors have gained increasing attention in past years due to their diverse applications in bioimaging, biosensing, and enzymatic assays. Given the potential of DNA/AgNCs for practical applications, the systematic studies of the fluorescent stability over an extended period is necessary. However, the correlation between nucleic acid properties and the long-term stability of DNA/AgNCs is less known. With locking-to-unlocking sensors, in which the secondary structure of DNA template is standardized, we investigated the correlation between the DNA structure and the fluorescence stability of AgNCs. Post-synthesis of DNA/AgNCs, the fluorescence, and structures of templates were monitored over three weeks. By combining the fluorescence spectroscopy with the in-gel fluorescent assay, we found that AgNCs encapsulated by dimer-structured DNA/AgNCs templates were more stable than those of hairpin-structured DNA/AgNCs templates. While the orange fluorescence from the dimer templates increased over three weeks, the red fluorescence from the hairpin templates was diminished by >80% within two days at room temperature. Further tests revealed that hairpin-encapsulated red-emissive AgNCs is more sensitive to oxidation by atmospheric oxygen compared to dimer encapsulated orange AgNCs. Our observations may provide an important clue in encapsulating photophysically more stable AgNCs by tuning the DNA secondary structures. The proposed strategy here can be essential for pragmatic applications of DNA/AgNCs templates.

Highlights

In recent years, the applications of the fluorescent properties of AgNCs have been increasing at a staggering rate
With locking-to-unlocking sensors, in which the secondary structure of DNA template is standardized, we investigated the correlation between the DNA structure and the fluorescence stability of AgNCs
By combining the fluorescence spectroscopy with the in-gel fluorescent assay, we found that AgNCs encapsulated by dimer-structured DNA/AgNCs templates were more stable than those of hairpin-structured DNA/AgNCs templates

Summary

Introduction

The applications of the fluorescent properties of AgNCs have been increasing at a staggering rate. The technologies developed using the photophysical properties of AgNCs for the detection of pathogens, single nucleotide polymorphism and microRNA biomarkers have been suggested for clinical diagnostics [10,11,12,13,14] To optimize these DNA/AgNCs based sensing methods, many studies have defined chemical and physical factors of DNA template that modulate the fluorescent properties of DNA/AgNCs. For instance, the sequences of DNA template, secondary structures of DNA, Guanine proximity and flexibility of nucleic acid templates are among the important determinants of emission wavelength and fluorescent intensity [11,15,16,17,18,19]. Specific DNA sequences are shown to increase the stability of emissive DNA/AgNCs [20,21,22]

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