Laila Al-Qarni
New Jersey Institute of Technology
USA
Title: Gold nanoparticles assembled on multilayer graphene sheets for surface enhanced Raman spectroscopy of glucose and related organic pollutants
Biography
Biography: Laila Al-Qarni
Abstract
The small normal Raman cross-section of glucose is considered a major issue for their detection by surface enhanced Raman spectroscopy (SERS) for medical applications, such as blood glucose level monitoring of diabetic patients and evaluation of patients with other medical conditions since glucose is a marker for many human diseases. Similarly, organic contaminants such as toluene suspended in drinking water require detection and removal. In this work, we report the use of commercial multilayer graphene sheets as substrates on which gold nanoparticles are chemically assembled by citrate reduction. The results show that these substrates are capable of providing SERS enhancement factors up to 1010 with a detection limit to 10-8 M in aqueous solutions of glucose. The SERS performance on graphene substrates are many orders of magnitude higher compared with results on gold coated chemically etched Klarite® silicon substrates. The glucose spectra over a wide range of concentrations in the 400-1500 cm-1 fingerprint region were recorded with a Thermo Scientific DXR Raman microspectrometer using 785 nm laser wavelength, 10 mW laser power and a 50x microscope objective. The intensity of the 1340 cm-1 line of glucose in particular varied linearly with glucose concentration and can be used as a calibration for samples of unknown concentrations. Chemometric methods were used to provide improved spectra at very low concentrations. The role of fractional charge transfer effects from the graphene substrate to glucose that could provide secondary enhancement of the spectra will also be evaluated [1]. Similar preliminary results on toluene suspended in water related to water contamination will also be presented.