Abstract
Detection of biomolecules is highly important for biomedical and other biological applications. Although several methods exist for the detection of biomolecules, surface enhanced Raman scattering (SERS) has a unique role in greatly enhancing the sensitivity. In this work, we have demonstrated the use of natural plant leaves as facile, low cost and eco-friendly SERS substrates for the sensitive detection of biomolecules. Specifically, we have investigated the influence of surface topography of five different plant leaf based substrates, deposited with Au, on the SERS performance by using L-cysteine as a model biomolecule. In addition, we have also compared the effect of sputter deposition of Au thin film with dropcast deposition of Au nanoparticles on the leaf substrates. Our results indicate that L-cysteine could be detected with high sensitivity using these plant leaf based substrates and the leaf possessing hierarchical micro/nanostructures on its surface shows higher SERS enhancement compared to a leaf having a nearplanar surface. Furthermore, leaves with drop-casted Au nanoparticle clusters performed better than the leaves sputter deposited with a thin Au film.
Highlights
There are various types of important biomolecules that are responsible for the maintenance of metabolic processes in living organisms [1]
We report a strategy for the sensitive detection of biomolecules by surface enhanced Raman scattering (SERS) technique, employing natural plant leaves deposited with Au as substrates
In order to prevent the leaves from dehydration, which results in the curling and loss in the surface activity, the leaves were fixated with the glutaraldehyde and water content was replaced by the glycerol to make them stable and preserve the surface topography
Summary
There are various types of important biomolecules that are responsible for the maintenance of metabolic processes in living organisms [1]. The nanostructures of noble and transition metals onto which the molecules are adsorbed can lead to 1010 to 1015 fold enhancement of the intensity of Raman scattered light and the effect is reported to be strongest on Ag followed by Au and Cu [10] Further moving in this field, improvement in the sensitivity of SERS signal and performance has been amplified by arranging the nanostructures into a threedimensional structure by many ways such as placing the plasmonic nanostructures directly or combining plasmonic nanostructures with non-plasmonic frameworks [13]. In one of our recent works, we have reported on the use of gold deposited plant leaves for SERS application for the detection of polar and non-polar analytes, wherein we had elaborated the role of surface morphology, wettability and deposition technique in determining the enhancement factor and detection limit [25]. A comparison between the two fabrication approaches is presented in this work
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