Raman and Fluorescence Enhancement Approaches in Graphene-Based Platforms for Optical Sensing and Imaging

Abstract

The search for novel platforms and metamaterials for the enhancement of optical and particularly Raman signals is still an objective since optical techniques offer affordable, noninvasive methods with high spatial resolution and penetration depth adequate to detect and image a large variety of systems, from 2D materials to molecules in complex media and tissues. Definitely, plasmonic materials produce the most efficient enhancement through the surface-enhanced Raman scattering (SERS) process, allowing single-molecule detection, and are the most studied ones. Here we focus on less explored aspects of SERS such as the role of the inter-nanoparticle (NP) distance and the ultra-small NP size limit (down to a few nm) and on novel approaches involving graphene and graphene-related materials. The issues on reproducibility and homogeneity for the quantification of the probe molecules will also be discussed. Other light enhancement mechanisms, in particular resonant and interference Raman scatterings, as well as the platforms that allow combining several of them, are presented in this review with a special focus on the possibilities that graphene offers for the design and fabrication of novel architectures. Recent fluorescence enhancement platforms and strategies, so important for bio-detection and imaging, are reviewed as well as the relevance of graphene oxide and graphene/carbon nanodots in the field.

Multiple‐Resonance‐Enhanced Raman Spectroscopy in 2D‐Material‐Capped Tapered‐Fiber Microcavity

“…Moreover, Figure S4 (Supporting Information) shows the PL spectra of ML‐MoS 2 and the UV–vis absorptance of the four dye molecules. The overlap between PL emission of ML‐MoS 2 and UV–vis absorptance of MB molecules indicated the existence of FRET energy transfer from ML‐MoS 2 to MB molecules, [ 50 ] where the TOF enhanced the PL emission from ML‐MoS 2 by Purcell effect and then the MB molecules absorbed the radiative photons to increase the state of electron density for promoting the cross section of Raman scattering. The Raman intensity of MB molecules on ML‐MoS 2 /TOF were therefore dramatically boosted by the above‐mentioned excitonic, molecular and CT resonances as well as promoted FRET.…”

Advances in the application of Raman spectroscopy in haematological tumours

“…Another significant drawback is the sample’s inherent spontaneous fluorescence. Because specific molecules and contaminants in the extracellular matrix may interact with input light to produce fluorescent photons with greater efficiency than scattered photons, interfering with the Raman spectrum, this is a particular difficulty in the interior environment of biological tissues ( Cortijo-Campos et al, 2021 ). Raman signals from biological tissues are usually weak, and the signal-to-noise ratio of the spectrum will also affect the accuracy of the measurement ( Wróbel et al, 2021 ).…”

One-Step Homogeneous Immunoassay for the Detection of Influenza Virus Using Switching Peptide and Graphene Quencher

“…As the antibodies show fluorescence after binding to fluorescence-labeled switching peptides, a quencher molecule should be bound to the detection antibodies to absorb the fluorescence from the switching peptides before the binding of antigens (target analytes). Fluorescence quenching effect by graphene is well-known to be occurred by energy transfer from the excited molecule to graphene [ 12 – 14 ]. Then, the excited electron in the valence band of graphene relaxes to the Fermi level non-radiatively.…”