Versatile Silver Nanoparticles-Based SERS Substrate with High Sensitivity and Stability

Mimi Liu,Mujtaba Ali Haqqani Mohammed,Anjuli Bhandari,Cheng-Yu Lai,Daniela R Radu

doi:10.3390/applnano2030017

Mimi Liu, Mujtaba Ali Haqqani Mohammed + Show 3 more

Open Access

https://doi.org/10.3390/applnano2030017

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Abstract

Surface-enhanced Raman scattering has developed into a mature analytical technique useful in various applications; however, the reproducible fabrication of a portable SERS substrate with high sensitivity and good uniformity is still an ongoing pursuit. Reported herein is a rapid fabrication method of an inexpensive SERS substrate that enables sub-nanomolar detection of molecular analytes. The SERS substrate is obtained by application of silver nanoparticles (Ag NPs)-based ink in precisely design patterns with the aid of an in-house assembled printer equipped with a user-fillable pen. Finite-difference time-domain (FDTD) simulations show a 155-times Ag NP electric field enhancement for Ag nanoparticle pairs with particle spacing of 2 nm. By comparing the SERS performance of SERS substrate made with different support matrices and fabrication methods, the PET-printed substrate shows optimal performance, with an estimated sensitivity enhancement factor of 107. The quantitative analysis of rhodamine 6G absorbed on optimized SERS substrate exhibits a good linear relationship, with a correlation coefficient (R2) of 0.9998, between the SERS intensity at 610 cm−1 and the concentration in the range of 0.1 nM—1μM. The practical low limit detection of R6G is 10 pM. The optimized SERS substrates show good stability (at least one month) and have been effectively tested in the detection of cancer drugs, including doxorubicin and metvan.

Highlights

In the synthesis of Ag NPs, diethanolamine was employed as the reducing agent; the mechanism involves the conversion of the hydroxyl group of diethanolamine into an aldehyde group to reduce Ag+ cation to Ag0 [46,47,53]
Face-centered cubic (FCC) Ag NPs synthesized through a solution-phase method were used to prepare a printable Ag ink, which was subsequently loaded in a userfillable pen and employed either by hand or by an in-house assembled printing machine to fabricate Surface-enhanced Raman scattering (SERS) substrates
NPs ink through a scalable method, we developed a highly sensitive, reproducible, and cost-effective method to detect any Raman active analyte on substrates with long-term stability

Summary

Introduction

Received: 26 July 2021Accepted: 13 August 2021Published: 25 August 2021Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.Licensee MDPI, Basel, Switzerland.Attribution (CC BY) license (https://creativecommons.org/licenses/by/ 4.0/).Surface-enhanced Raman scattering (SERS) has been extensively studied since discovering the ability of the nanostructured plasmonic metal surfaces to enhance the Raman scattering of molecules in contact or proximity to such metal surfaces. SERS effect was discovered by Fleischmann et al in 1974 when an enhanced Raman signal was observed for the pyridine absorbed on the surface of a rough silver electrode [1]. In 1977, Jeanmaire et al.

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