A New Strategy for Silver Deposition on Au Nanoparticles with the Use of Peroxidase-Mimicking DNAzyme Monitored via a Localized Surface Plasmon Resonance Technique.

Joanna Kosman,Jacqueline Jatschka,Bernard Juskowiak,Ondrej Stranik,Andrea Csaki,Wolfgang Fritzsche

doi:10.3390/s17040849

Abstract

Peroxidase-mimicking DNAzyme was applied as a catalyst of silver deposition on gold nanoparticles. This DNAzyme is formed when hemin binds to the G-quadruplex-forming DNA sequence. Such a system is able to catalyze a redox reaction with a one- or two-electron transfer. The process of silver deposition was monitored via a localized surface plasmon resonance technique (LSPR), which allows one to record scattering spectrum of a single nanoparticle. Our study showed that DNAzyme is able to catalyze silver deposition. The AFM experiments proved that DNAzyme induced the deposition of silver shells of approximately 20 nm thickness on Au nanoparticles (AuNPs). Such an effect is not observed when hemin is absent in the system. However, we noticed non-specific binding of hemin to the capture oligonucleotides on a gold NP probe that also induced some silver deposition, even though the capture probe was unable to form G-quadruplex. Analysis of SEM images indicated that the surface morphology of the silver layer deposited by DNAzyme is different from that obtained for hemin alone. The proposed strategy of silver layer synthesis on gold nanoparticles catalyzed by DNAzyme is an innovative approach and can be applied in bioanalysis (LSPR, electrochemistry) as well as in material sciences.

Highlights

DNAzymes are specific DNA oligonucleotides, which possess catalytic activity [1]
We show that DNAzyme based on the PS2.M sequence can be used for silver deposition on gold nanoparticles
The design of experimental setup is depicted on Scheme 1

Summary

Introduction

DNAzymes are specific DNA oligonucleotides, which possess catalytic activity [1]. The search for novel catalytic systems different from protein enzymes was dictated by drawbacks of popular enzymes. DNAzymes in comparison with proteins are more thermally stable, simpler in synthesis and purification, and can hybridize with complementary strands. One of the most attracting systems nowadays is a DNAzyme with peroxidase activity, which can catalyze the reaction between H2 O2 and suitable substrate [2]. To form DNAzyme, DNA oligonucleotide must first adopt G-quadruplex structure and create complex with hemin. Most of the bioassays based on this system use two kinds of substrates: luminol (chemiluminescence readout) or ABTS (colorimetric signal) [3]. The progress in DNAzyme-related studies is advancing in two directions.

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Conclusion