Silver-Graphene Oxide Nanohybrids for Highly Sensitive, Stable SERS Platforms.

Mateusz Kasztelan,Grażyna Zofia Żukowska,Anna Studzinska,Barbara Pałys

doi:10.3389/fchem.2021.665205

Mateusz Kasztelan, Grażyna Zofia Żukowska + Show 2 more

Open Access

https://doi.org/10.3389/fchem.2021.665205

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Abstract

Graphene oxide–silver nanoparticle nanohybrids were synthesized by simple reduction of the silver nitrate and graphene oxide (GO) mixture in water using the mild reducing agent ascorbic acid. The concentration of ascorbic acid was varied to verify the possible influence of the GO surface composition on the efficiency of the hybrid material as substrates for surface enhanced Raman spectroscopy (SERS). Furthermore, the composites were conditioned in ammonia solution or in potassium hydroxide diluted solution. For comparison, the graphene oxide–silver nanoparticle composite has been synthesized using the ammonia-treated GO. All materials were characterized using spectroscopic and microscopic methods including UV–Vis, infrared, and Raman spectroscopy and scanning electron microscopy. The SERS efficiency of the nanohybrids was tested using 4-aminothiophenol (PATP). The optimal synthesis conditions were found. Ammonia and potassium peroxide drop-casted on the composite changed the SERS properties. The sample treated with KOH showed the best SERS enhancement. The variation of the SERS enhancement was correlated with the shape of the UV–Vis characteristics and the surface structure of the composites.

Highlights

Surface enhanced Raman spectroscopy (SERS) shows exceptional sensitivity, enabling detection of analytes at micromolar or lower concentrations (Zhang et al, 2017)
The concentration of ascorbic acid used for the synthesis of AgNPs@rGO nanohybrids has a significant impact on the obtained composite, including the shape and the amount of silver nanostructures formed on the GO layers
The SERS efficiency of the studied hybrid materials can be placed in an order: AgNPs@rGO < AgNPs@ rGO + NH3 < AgNPs@rGO/NH3 < AgNPs@rGO + KOH

Summary

Introduction

Surface enhanced Raman spectroscopy (SERS) shows exceptional sensitivity, enabling detection of analytes at micromolar or lower concentrations (Zhang et al, 2017). SERS probes designed with antigens or aptamers are used for the highly sensitive detection of cancer cells and biologically important molecules (Wu et al, 2012; Darrigues et al, 2017). It was generally agreed that localized surface plasmon resonance is responsible for the largest part of the enhancement of the Raman signal (Langer et al, 2020). Another factor is the chemical effect resulting from the charge transfer between the SERS-active material and the adsorbed molecule. The chemical enhancement is much lower than the plasmon resonance contribution, but it

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