Molecular sensitivity of metal nanoparticles decorated graphene‐family nanomaterials as surface‐enhanced Raman scattering (SERS) platforms

Abstract

Graphene‐mediated surface enhanced Raman scattering is a recent phenomenon that produces clean and reproducible signals from chemical analytes. In this work, we report on the development of graphene‐family nanomaterials (graphene oxide; GO, reduced GO; rGO, and multilayer graphene; MLG) decorated with physisorbed silver (AgNP) and gold (AuNP) nanoparticles and as layered architectures for detection of methylene blue and rhodamine 6G dyes in view of optical and biological significance. The experimental results illustrate four orders of magnitude graphene‐mediated surface enhanced Raman scattering enhancement in the order rGO/AgNP > GO/AgNP > MLG/AgNP for physisorbed and cascade amplified signal on multilayer architectures, larger than those only on graphene and metal nanoparticles, which is achieved at optimal size of Ag (30 nm) and Au (40 nm) on rGO. Moreover, highly‐sensitive graphene‐decorated nanoparticle are capable of molecular detection over a broad concentration range 10 pM–100 μM. The findings are discussed in terms of (a) strong graphene‐metal nanoparticle coupling leading to local interfacial hybridization and polarization, (b) molecular structural symmetry of analytes in relation to nanoparticle‐graphene functionalities, and (c) effective charge transfer and exchange or sharing of charges between analyte and nanoparticles decorated graphene. Optimized metal nanoparticle‐graphene geometries and electronic properties are determined from density functional theory calculations. They identify preferred metal nanoparticle adsorption sites and long‐range electrostatic interactions and determine relative resonant charge transfer population (alternatively, chemical enhancement mechanism) values derived from the Mulliken population thus gaining insights into effective enhancement factors. These findings will help to design advanced SERS platforms for ultrasensitive detection of chemicals and biological molecules useful in bio‐nanotechnology.

Graphene Quantum Dots Electrochemistry and Sensitive Electrocatalytic Glucose Sensor Development

“…The cyclic and differential pulse voltammograms shown in Figure 5 a,b, respectively, are in presence of 0.1 M PBS with glucose from 0.5 to 3 mM concentration. While the redox peaks are almost absent in CV profiles, the DPV curves exhibit a decline in reduction peak with increasing glucose concentration, ascribed to the decrease in oxygen on the electrode surface caused by the enzyme-catalyzed reaction between the oxidized form of GO x (FAD) and glucose following the Glucose + GO x (FAD) → gluconolactone (C 6 H 10 O 6 ) + GO x (FADH 2 ) reaction [ 58 ]. The current decrease is quasi-linearly proportional to glucose addition, suggestive of determination of sensitivity of glucose concentration.…”

Recent advances in linear and nonlinear Raman spectroscopy. Part XIII

“…Gupta and co‐workers described the molecular sensitivity of metal NPs that decorated graphene family nanomaterials as SERS platforms. Their findings will help to design advanced SERS platforms for ultrasensitive detection of chemicals and biological molecules useful in biotechnology and nanotechnology . Kim and co‐workers reported changes in the Raman spectra of monolayer MoS 2 upon thermal annealing.…”

“…Their findings will help to design advanced SERS platforms for ultrasensitive detection of chemicals and biological molecules useful in biotechnology and nanotechnology. [91] Kim and co-workers reported changes in the Raman spectra of monolayer MoS 2 upon thermal annealing. In particular, they measured the changes in the Raman spectra and electrical conductance of monolayer MoS 2 with increasing defects via thermal annealing in a reducing atmosphere.…”

In‐Situ covalent synthesis of gold nanorods on GO surface as ultrasensitive Raman probe

“…In recent years, Raman probes or sensors which originating from surface‐enhanced (SERS) Raman scattering has attracted broad interest in scientific community due to its unique optical properties and wide applications . A good substrate for Raman probes is the key point to get high sensitivity.…”

“…In recent years, Raman probes or sensors which originating from surface-enhanced (SERS) Raman scattering has attracted broad interest in scientific community due to its unique optical properties and wide applications. [1][2][3][4][5][6] A good substrate for Raman probes is the key point to get high sensitivity. Normally, rough surface of a noble metal such as Ag and Au is often used as SERS substrate of Raman probe because of the huge electromagnetic mechanism (EM) which relies on the enhancement of local electromagnetic field.…”